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Journal Cover Plant Physiology and Biochemistry
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0981-9428
   Published by Elsevier Homepage  [3043 journals]
  • Exogenous application of poly-γ-glutamic acid enhances stress defense in
           Brassica napus L. seedlings by inducing cross-talks between Ca2+, H2O2,
           brassinolide, and jasmonic acid in leaves
    • Authors: Huashan Li; Peng Lei; Xiao Pang; Sha Li; Hong Xu; Zongqi Xu; Xiaohai Feng
      Pages: 26 - 34
      Abstract: Publication date: Available online 17 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Zongqi Xu, Peng Lei, Xiao Pang, Huashan Li, Xiaohai Feng, Hong Xu
      Poly-γ-glutamic acid (γ-PGA) is a microbe-secreted isopeptide shown to promote growth and enhance crop stress tolerance. However, its downstream signaling pathways are unknown. Here, we studied γ-PGA-induced tolerance to salt and cold stresses. Pretreatment with γ-PGA contributed to enhance stress tolerance of canola seedlings by promoting proline accumulation and total antioxidant capacity (T-AOC) improvement. Further, Ca2+, H2O2, brassinolide, and jasmonic acid were found to be involved in the γ-PGA-induced process. First, using signal blockers, we concluded that γ-PGA activated Ca2+ fluctuations in canola seedling leaves. Second, the activated Ca2+ further elicited H2O2 production by Ca2+-binding proteins CBL9, CPK4, and CPK5. Third, the H2O2 signal promoted brassinolide and jasmonic acid biosynthesis by upregulating key genes (DWF4 and LOX2, respectively) for synthesizing these compounds. Lastly, brassinolide and jasmonic acid increased H2O2 which promoted proline accumulation and T-AOC improvement and further enhanced Ca2+-binding proteins including CaM, CBL10, and CPK9.

      PubDate: 2017-07-21T20:29:33Z
      DOI: 10.1016/j.apsoil.2017.05.033
      Issue No: Vol. 119 (2017)
       
  • Effect of seasonality and Cr(VI) on starch-sucrose partitioning and
           related enzymes in floating leaves of Salvinia minima
    • Authors: Mariana Rosa; Carolina Prado; Silvana Chocobar-Ponce; Eduardo Pagano; Fernando Prado
      Pages: 1 - 10
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Mariana Rosa, Carolina Prado, Silvana Chocobar-Ponce, Eduardo Pagano, Fernando Prado
      Effects of seasonality and increasing Cr(VI) concentrations on leaf starch-sucrose partitioning, sucrose- and starch-related enzyme activities, and carbon allocation toward leaf development were analyzed in fronds (floating leaves) of the floating fern Salvinia minima. Carbohydrates and enzyme activities of Cr-exposed fronds showed different patterns in winter and summer. Total soluble sugars, starch, glucose and fructose increased in winter fronds, while sucrose was higher in summer ones. Starch and soluble carbohydrates, except glucose, increased under increasing Cr(VI) concentrations in winter fronds, while in summer ones only sucrose increased under Cr(VI) treatment. In summer fronds starch, total soluble sugars, fructose and glucose practically stayed without changes in all assayed Cr(VI) concentrations. Enzyme activities related to starch and sucrose metabolisms (e.g. ADPGase, SPS, SS and AI) were higher in winter fronds than in summer ones. Total amylase and cFBPase activities were higher in summer fronds. Cr(VI) treatment increased enzyme activities, except ADPGase, in both winter and summer fronds but no clear pattern changes were observed. Data of this study show clearly that carbohydrate metabolism is differently perturbed by both seasonality and Cr(VI) treatment in summer and winter fronds, which affects leaf starch-sucrose partitioning and specific leaf area (SLA) in terms of carbon investment.

      PubDate: 2017-06-06T20:29:25Z
      DOI: 10.1016/j.plaphy.2017.05.014
      Issue No: Vol. 118 (2017)
       
  • Endopolyploidy levels in barley vary in different root types and
           significantly decrease under phosphorus deficiency
    • Authors: Zhanghui Zeng; Huahong Huang; Ning Han; Chun Y. Huang; Peter Langridge; Hongwu Bian; Muyuan Zhu
      Pages: 11 - 21
      Abstract: Publication date: Available online 5 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Zhanghui Zeng, Huahong Huang, Ning Han, Chun Y. Huang, Peter Langridge, Hongwu Bian, Muyuan Zhu
      Increased endopolyploidy is important for plant growth and development as well as for adaptation to environmental stresses. However, little is known about the role of reduced endopolyploidy, especially in root systems. In this report, endopolyploidy variations were examined in different types of barley (Hordeum vulgare L.) roots, and the effects of phosphorus (P) deficiency and salinity (NaCl) stress on root endopolyploidy were also studied. The results showed that the endopolyploidy levels were lower in lateral roots than in either primary or nodal roots. The lower endopolyploidy in lateral roots was attributed to cortical cells. P deficiency reduced the endopolyploidy levels in lateral roots and mature zone of primary roots. By contrast, salinity had no effects on the endopolyploidy levels in either lateral or primary roots, but had a minor effect on nodal roots. Transcript analysis of cell cycle-related genes showed that multiple cell cycle-related genes were more highly expressed in lateral roots than in primary roots, suggesting their roles in lowering endopolyploidy. P deficiency reduced HvCCS52A1 transcripts in the mature zone of primary roots, but had little effect on the transcripts of 12 cell cycle-related genes in lateral roots, suggesting that endopolyploidy regulation differs between lateral roots and primary roots. Our results revealed that endopolyploidy reduction in root systems could be an integrated part of endopolyploidy plasticity in barley growth and development as well as in adaptation to a low P environment.

      PubDate: 2017-06-06T20:29:25Z
      DOI: 10.1016/j.plaphy.2017.06.004
      Issue No: Vol. 118 (2017)
       
  • Pattern of expression and interaction specificity of multiple G-protein
           beta (Gβ) subunit isoforms with their potential target proteins reveal
           functional dominance of BjuGβ1 in the allotetraploid Brassica juncea
    • Authors: Roshan Kumar; Aprajita Sharma; Ishita Chandel; Naveen C. Bisht
      Pages: 22 - 30
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Roshan Kumar, Aprajita Sharma, Ishita Chandel, Naveen C. Bisht
      Heterotrimeric G-protein, consisting Gα, Gβ and Gγ subunits, interacts with various upstream and downstream effector (target) proteins to regulate a large array of conserved and species-specific biological functions. The targets of G-protein components are recently reported in model plant Arabidopsis thaliana; however limited information is available from crop species. In this study, we utilized yeast two-hybrid (Y2H) assay to screen the diversity of interacting partners of multiple Gβ subunit isoforms from allotetraploid Brassica juncea, a globally important oilseed and vegetable crop. The three BjuGβ genes (BjuGβ1-3), resulted from whole genome triplication event in Brassica lineage, showed distinct expression profile during plant developmental stages with maximal transcript abundance during reproductive stages. Protein-protein interaction of three BjuGβ proteins (bait) against the Y2H cDNA library (prey) identified a total of 14 and 1 non-redundant targets for BjuGβ1 and BjuGβ2, whereas BjuGβ3 screening surprisingly did not yield any genuine target, thereby suggesting functional dominance of BjuGβ1. The triplicated BjuGβ isoforms showed a high degree of interaction strength and specificity with the identified target proteins, which are known to be involved in diverse biological functions in plants. qRT-PCR analysis further indicated that the expression of BjuGβ-target genes was developmentally regulated under various tissue types studied and showed a high degree of co-expression pattern with the BjuGβ genes, particularly during flower and silique development in B. juncea. Taken together, our data provides novel insights on pattern of expression and interaction specificity governing functional divergence of multiple Gβ subunit proteins in polyploid B. juncea.

      PubDate: 2017-06-11T20:33:30Z
      DOI: 10.1016/j.plaphy.2017.05.020
      Issue No: Vol. 118 (2017)
       
  • Regulation and physiological role of silicon in alleviating drought stress
           of mango
    • Authors: Mohamed Naser Helaly; Hanan El-Hoseiny; Nabil Ibrahim El-Sheery; Anshu Rastogi; Hazem M. Kalaji
      Pages: 31 - 44
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Mohamed Naser Helaly, Hanan El-Hoseiny, Nabil Ibrahim El-Sheery, Anshu Rastogi, Hazem M. Kalaji
      Improvement of drought stress of mango plants requires intensive research that focuses on physiological processes. In three successive seasons (2014, 2015and 2016) field experiments with four different strains of mango were subjected to two water regimes. The growth and physiological parameters of possible relevance for drought stress tolerances in mango were investigated. Yield and its components were also evaluated. The data showed that all growth and physiological parameters were increased under K2SiO3 (Si) supplement and were followed by the interaction treatment (Si treatment and its combination with drought stress) compared to that of the controlled condition. Drought stress decreased the concentration of auxins (IAA), gibberellins (GA) and cytokinins (CK) in the three mango cultivars leaves, whereas, it increased the concentration of abscisic acid (ABA). On the contrary, IAA, GA, and CK (promoters) endogenous levels were improved by supplementing Si, in contrary ABA was decreased. Drought stress increased the activity of peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD) in the leaves of all mango cultivars grown during three experimental seasons. However, Si supplementation reduced the levels of all these antioxidative enzymes, especially the concentration of SOD when compared to that of control leaves. Fruit quality was improved in three successive seasons when Si was applied. Our results clearly show that the increment in drought tolerance was associated with an increase in antioxidative enzyme activity, allowing mango plants to cope better with drought stress. Si possesses an efficient system for scavenging reactive oxygen species, which protects the plant against destructive oxidative reactions, thereby improving the ability of the mango trees to withstand environmental stress in arid regions.

      PubDate: 2017-07-01T16:44:52Z
      DOI: 10.1016/j.plaphy.2017.05.021
      Issue No: Vol. 118 (2017)
       
  • Seed soaking in I and Se solutions increases concentrations of both
           elements and changes morphological and some physiological parameters of
           pea sprouts
    • Authors: Ana Jerše; Nina Kacjan-Maršić; Helena Šircelj; Mateja Germ; Ana Kroflič; Vekoslava Stibilj
      Pages: 285 - 294
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Ana Jerše, Nina Kacjan-Maršić, Helena Šircelj, Mateja Germ, Ana Kroflič, Vekoslava Stibilj
      Pea (Pisum sativum L., cv. ‘Petit Provencal’) seeds were soaked in solutions of different iodine (I) and selenium (Se) forms (1000 mg I L−1 and 10 mg Se L−1). Iodine and selenium content in different parts of pea sprouts, as well as morphological, biochemical and physiological characteristics were measured in sprouts. The results showed increased concentrations of both elements in sprouts grown from treated seeds. Soaking influenced the biomass and height of the sprouts. Significant differences between plants grown from treated seeds in comparison with control plants were also observed for electron transport system activity and concentrations of tocopherol and glutathione. On the other hand, the content of photosynthetic pigments and anthocyanins remained similar as in control plants. Potential photochemical efficiency of photosystem II was close to theoretical maximum 0.8 in all samples. From the pattern of changes of stress indicators we suppose that plants adapted to the stress earlier in the experiment, i.e. before they were sampled for physiological measurements.
      Graphical abstract image

      PubDate: 2017-07-01T16:44:52Z
      DOI: 10.1016/j.plaphy.2017.06.009
      Issue No: Vol. 118 (2017)
       
  • The utility of biochemical, physiological and morphological biomarkers of
           leaf sulfate levels in establishing Brachylaena discolor leaves as a
           bioindicator of SO2 pollution
    • Authors: Candyce Ann Areington; Boby Varghese; Sershen
      Pages: 295 - 305
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Candyce Ann Areington, Boby Varghese, Sershen
      The negative impacts of air pollution have made monitoring of air quality increasingly important, especially in heavily industrialized areas such as the South Durban Basin (SDB), in South Africa. Bioindicators such as trees can complement conventional air quality monitoring and be used to prioritise vulnerable areas. This study assessed the utility of Brachylaena discolor DC. tree leaves as a bioindicator of sulfur dioxide pollution. This involved correlating ground level sulfur dioxide concentrations ([SO2]) with B. discolor leaf sulfate concentrations ([sulfate]) at three industrial (treatment) sites within the SBD and control site at which [SO2] was significantly lower for all four seasons. Based on this significant positive correlation between the aforementioned (p = 0.005; ρ = 0.667) leaf sulfate levels were related to various biochemical (intracellular hydrogen peroxide production, total aqueous [TAA] and enzymic antioxidants [superoxide dismutase and catalase], lipid peroxidation [LPO] and electrolyte leakage), physiological (leaf chlorophyll fluorescence [LCF] and relative chlorophyll content) and morphological (leaf area [LA]) biomarkers of stress measured on leaves from trees at the treatment and control sites. Annual [SO2] and leaf [sulfate] at the treatments were significantly (p < 0.05) higher than the control and high by global standards. TAA, LPO, electrolyte leakage, LCF, and LA were significantly (p < 0.05) correlated with seasonal [sulfate]. Except for superoxide dismutase, catalase and relative chlorophyll content all other biomarkers could differentiate between the treatment sites and the control. However, TAA, electrolyte leakage and LA were the only biomarkers sensitive enough to reflect differences in annual [sulfate] across the treatment sites; these should be used to establish B. discolor leaves as a bioindicator of SO2 pollution.

      PubDate: 2017-07-01T16:44:52Z
      DOI: 10.1016/j.plaphy.2017.06.025
      Issue No: Vol. 118 (2017)
       
  • Nuclear localization and transactivation by Vitis CBF transcription
           factors are regulated by combinations of conserved amino acid domains
    • Authors: Chevonne E. Carlow; J. Trent Faultless; Christine Lee; Mahbuba Siddiqua; Alison Edge; Annette Nassuth
      Pages: 306 - 319
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Chevonne E. Carlow, J. Trent Faultless, Christine Lee, Mahbuba Siddiqua, Alison Edge, Annette Nassuth
      The highly conserved CBF pathway is crucial in the regulation of plant responses to low temperatures. Extensive analysis of Arabidopsis CBF proteins revealed that their functions rely on several conserved amino acid domains although the exact function of each domain is disputed. The question was what functions similar domains have in CBFs from other, overwintering woody plants such as Vitis, which likely have a more involved regulation than the model plant Arabidopsis. A total of seven CBF genes were cloned and sequenced from V. riparia and the less frost tolerant V. vinifera. The deduced species-specific amino acid sequences differ in only a few amino acids, mostly in non-conserved regions. Amino acid sequence comparison and phylogenetic analysis showed two distinct groups of Vitis CBFs. One group contains CBF1, CBF2, CBF3 and CBF8 and the other group contains CBF4, CBF5 and CBF6. Transient transactivation assays showed that all Vitis CBFs except CBF5 activate via a CRT or DRE promoter element, whereby Vitis CBF3 and 4 prefer a CRT element. The hydrophobic domains in the C-terminal end of VrCBF6 were shown to be important for how well it activates. The putative nuclear localization domain of Vitis CBF1 was shown to be sufficient for nuclear localization, in contrast to previous reports for AtCBF1, and also important for transactivation. The latter highlights the value of careful analysis of domain functions instead of reliance on computer predictions and published data for other related proteins.

      PubDate: 2017-07-01T16:44:52Z
      DOI: 10.1016/j.plaphy.2017.06.027
      Issue No: Vol. 118 (2017)
       
  • Role of fusaric acid in the development of ‘Fusarium wilt’ symptoms in
           tomato: Physiological, biochemical and proteomic perspectives
    • Authors: Vivek Kumar Singh; Harikesh Bahadur Singh; Ram Sanmukh Upadhyay
      Pages: 320 - 332
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Vivek Kumar Singh, Harikesh Bahadur Singh, Ram Sanmukh Upadhyay
      Fusarium wilt is one of the most prevalent and damaging diseases of tomato. Among various toxins secreted by the Fusarium oxysporum f. sp. lycopersici (causal agent of Fusarium wilt of tomato), fusaric acid (FA) is suspected to be a potent pathogenicity factor in tomato wilt disease development. With this rationale the present study was carried out with physiological, biochemical and proteomic perspectives. Treatment of FA was given to the leaves of tomato directly through infiltration to show the characteristic features of Fusarium wilt of tomato. The phytotoxic effect of FA was assessed in the form of cell death in tomato leaves which was observed by increased uptake of Evans blue stain. The measurement of electrolyte leakage was used as an indicator of the extent of cell death. The influence of FA on the leaf photosynthesis of tomato plant was investigated and it was found that FA strongly reduced the photosynthetic pigment contents of tomato leaves resulting to heavy suppression of leaf photosynthesis processes, which therefore affected leaf physiology finally leading to leaf wilting and necrosis. This cell death inducer (FA) produced an enormous oxidative burst during which large quantities of reactive oxygen species (ROS) like H2O2 was generated in the treated leaf tissues of tomato plants which was evident from enhancement in lipid peroxidation. To assess the involvement of proteolysis in the cell death cascade induced by FA treatment, total protease activity was measured in the leaf tissues and it was found that the total protease activity increased with the treatment and leading to cell death. Furthermore, proteomic study was used as a powerful tool to understand the alterations in cellular protein expression in response to FA exposure. Differential expression in several proteins was observed in the present study. Proteomic analyses, thus, clearly indicate that proteins belonging to different functional classes are significantly affected in the plant leaf tissues after FA exposure leading to deterioration of structure and metabolism of cells. Thus, it is concluded that FA plays an important role in fungal pathogenicity by decreasing cell viability.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.06.028
      Issue No: Vol. 118 (2017)
       
  • Different roles of glutathione in copper and zinc chelation in Brassica
           napus roots
    • Authors: Ilya E. Zlobin; Alexander V. Kartashov; George V. Shpakovski
      Pages: 333 - 341
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Ilya E. Zlobin, Alexander V. Kartashov, George V. Shpakovski
      We investigated the specific features of copper and zinc excess action on the roots of canola (Brassica napus L.) plants. Copper rapidly accumulated in canola root cells and reached saturation during several hours of treatment, whereas the root zinc content increased relatively slowly. Excessive copper and zinc entry inside the cell resulted in significant cell damage, as evidenced by alterations in plasmalemma permeability and decreases in cellular enzymatic activity. Zinc excess specifically damaged root hair cells, which correlated with a pronounced elevation of their labile zinc level. In vitro, we showed that reduced glutathione (GSH) readily reacted with copper ions to form complexes with blocked sulfhydryl groups. In contrast, zinc ions were ineffective as glutathione blockers, and glutathione molecules did not lose their specific chemical activity in the presence of Zn2+ ions. The effect of copper and zinc excess on the glutathione pool in canola root cells was analysed by a combination of biochemical determination of total and oxidized glutathione contents and fluorescent staining of free reduced glutathione with monochlorobimane dye. Excess copper led to dose-dependent diminution of free reduced glutathione contents in the root cells, which could not be explained by the loss of total cellular glutathione or its oxidation. In contrast, we observed little effect of much higher intracellular zinc concentrations on the free reduced glutathione content. We concluded that GSH plays an important role in copper excess, but not zinc excess chelation, in canola root cells.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.06.029
      Issue No: Vol. 118 (2017)
       
  • Differential expression of CURS gene during various growth stages,
           climatic condition and soil nutrients in turmeric (Curcuma longa): Towards
           site specific cultivation for high curcumin yield
    • Authors: I. Sriram Sandeep; Suryasnata Das; Noohi Nasim; Antaryami Mishra; Laxmikanta Acharya; Raj Kumar Joshi; Sanghamitra Nayak; Sujata Mohanty
      Pages: 348 - 355
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): I. Sriram Sandeep, Suryasnata Das, Noohi Nasim, Antaryami Mishra, Laxmikanta Acharya, Raj Kumar Joshi, Sanghamitra Nayak, Sujata Mohanty
      Curcuma longa L., accumulates substantial amount of curcumin and essential oil. Little is known about the differential expression of curcumin synthase (CURS) gene and consequent curcumin content variations at different agroclimatic zones. The present study aimed to evaluate the effect of climate, soil and harvesting phase on expression of CURS gene for curcumin yield in two high yielding turmeric cultivars. Expression of CURS gene at different experimental zones as well as at different harvesting phase was studied through transcriptional analysis by qRT-PCR. Curcumin varied from 1.5 to 5% and 1.4–5% in Surama and Roma respectively. The expression of CURS also varied from 0.402 to 5.584 fold in Surama and 0.856–5.217 fold in Roma. Difference in curcumin content at a particular zone varied among different harvesting period from 3.95 to 4.31% in Surama and 3.57–3.83% in Roma. Expression of CURS gene was also effected by harvesting time of the rhizome which varied from 7.389 to 16.882 fold in Surama and 4.41–8.342 fold in Roma. The CURS gene expression was found regardless of variations in curcumin content at different experimental zones. This may be due to the effects of soil and environmental variables. Expression was positively correlated with curcumin content with different harvesting time at a particular zone. This find indicates effect of soil and environment on molecular and biochemical dynamics of curcumin biosynthesis and could be useful in genetic improvement of turmeric.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.001
      Issue No: Vol. 118 (2017)
       
  • Structural diversity of alkali-soluble polysaccharides from the fruit cell
           walls of tucumã (Astrocaryum aculeatum), a commelinid monocotyledon from
           the family Arecaceae
    • Authors: Thaisa Moro Cantu-Jungles; Marcello Iacomini; Thales R. Cipriani; Lucimara M.C. Cordeiro
      Pages: 356 - 361
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Thaisa Moro Cantu-Jungles, Marcello Iacomini, Thales R. Cipriani, Lucimara M.C. Cordeiro
      The polysaccharide compositions of primary and secondary cell walls of members of the family Arecaceae in the commelinid clade of monocotyledonous plants have previously been found to be distinguishable from other commelinid families, and to be more similar to those of non-commelinids. However, few studies have been conducted. We aimed to extract and characterize the main cell-wall polysaccharides in the fruit pulp of tucumã (Astrocaryum aculeatum), a member of Arecaceae family. Hemicellulosic polysaccharides extracted by alkali from the fruit pulp were present in greater proportions (6.4% yield) than water-extracted ones (3.0% yield). Thus, the former was analyzed using monosaccharide composition, methylation, molecular weight determination and 13C-NMR data. The tucumã alkaline extract presented a highly ramified acidic galactoarabinoxylan (53.7%), a linear (1 → 5)-linked α-L-arabinan (27.8%), a low branched glucuronoxylan (14.1%) and small portions of a xyloglucan (4.4%). The major polysaccharide found in A. aculeatum (acidic galactoarabinoxylan) is similar to those found in other commelinid plants such as grasses and cereals.
      Graphical abstract image

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.002
      Issue No: Vol. 118 (2017)
       
  • Seed priming and transgenerational drought memory improves tolerance
           against salt stress in bread wheat
    • Authors: Tahira Tabassum; Muhammad Farooq; Riaz Ahmad; Ali Zohaib; Abdul Wahid
      Pages: 362 - 369
      Abstract: Publication date: Available online 8 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Tahira Tabassum, Muhammad Farooq, Riaz Ahmad, Ali Zohaib, Abdul Wahid
      This study was conducted to evaluate the potential of seed priming following terminal drought on tolerance against salt stress in bread wheat. Drought was imposed in field sown wheat at reproductive stage (BBCH growth stage 49) and was maintained till physiological maturity (BBCH growth stage 83). Seeds of bread wheat, collected from crop raised under terminal drought and/or well-watered conditions, were subjected to hydropriming and osmopriming (with 1.5% CaCl2) and were sown in soil-filled pots. After stand establishment, salt stress treatments viz. 10 mM NaCl (control) and 100 mM NaCl were imposed. Seed from terminal drought stressed source had less fat (5%), and more fibers (11%), proteins (22%) and total soluble phenolics (514%) than well-watered seed source. Salt stress reduced the plant growth, perturbed water relations and decreased yield. However, an increase in osmolytes accumulation (4–18%), malondialdehyde (MDA) (27–35%) and tissue Na+ contents (149–332%) was observed under salt stress. The seeds collected from drought stressed crop had better tolerance against salt stress as indicated by better yield (28%), improved water relations (3–18%), osmolytes accumulation (21–33%), and less MDA (8%) and Na contents (35%) than progeny of well-watered crop. Seed priming, osmopriming in particular, further improved the tolerance against salt stress through improvement in leaf area, water relations, leaf proline, glycine betaine and grain yield while lowering MDA and Na+ contents. In conclusion, changed seed composition during terminal drought and seed priming improved the salt tolerance in wheat by modulating the water relations, osmolytes accumulation and lipid peroxidation.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.007
      Issue No: Vol. 118 (2017)
       
  • Effect of acibenzolar-S-methyl phototransformation on its elicitation
           activity in tobacco cells
    • Authors: Florent Lavergne; Claire Richard; Marc Saudreau; Jean-Stéphane Venisse; Boris Fumanal; Pascale Goupil
      Pages: 370 - 376
      Abstract: Publication date: Available online 8 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Florent Lavergne, Claire Richard, Marc Saudreau, Jean-Stéphane Venisse, Boris Fumanal, Pascale Goupil
      The plant activator acibenzolar-S-methyl (BTH) undergoes phototransformation when exposed to solar radiation. Here we investigated the changes in its elicitation properties on BY-2 tobacco cells at different stages of the photochemical reaction. Both pure BTH and formulated BTH were irradiated in controlled conditions to achieve different extents of conversion. Both pure BTH (900 μM) and Bion® (0.4 g.L−1) induced BY-2 cell death, but BTH photoconverted to an extent of 25 ± 3% lowered the cell death rate. A kinetic study of β-1,3-glucanase and chitinase activities was conducted on BY-2 extracellular medium. Exposure of tobacco cells to either pure BTH or Bion® resulted in a significant increase in the activities of both defense enzymes, which peaked 48 h after the treatment. The pathogenesis-related (PR) protein activities were quantified 48 h after elicitation for a range of phototransformed BTH solutions. The enzyme activities were reduced when BY-2 cells were treated with solutions in which BTH conversion was 22 ± 3%, 42 ± 3% and 100 ± 3%, but were not affected by the solution in which BTH was phototransformed at 60%, suggesting that some of the secondary photoproducts also exhibit eliciting properties. Solar irradiation of BTH thus impairs its elicitation properties, but this impairment depends strongly on the extent of phototransformation.
      Graphical abstract image

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.008
      Issue No: Vol. 118 (2017)
       
  • Ancient signal for nitrogen status sensing in the green lineage:
           Functional evidence of CDPK repertoire in Ostreococcus tauri
    • Authors: Gonzalo Caló; Dana Scheidegger; Giselle M.A. Martínez-Noël; Graciela L. Salerno
      Pages: 377 - 384
      Abstract: Publication date: Available online 8 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Gonzalo Caló, Dana Scheidegger, Giselle M.A. Martínez-Noël, Graciela L. Salerno
      Calcium-dependent protein kinases (CDPKs) regulate plant development and many stress signalling pathways through the complex cytosolic [Ca2+] signalling. The genome of Ostreococcus tauri (Ot), a model prasinophyte organism that is on the base of the green lineage, harbours three sequences homologous to those encoding plant CDPKs with the three characteristic conserved domains (protein kinase, autoregulatory/autoinhibitory, and regulatory domain). Phylogenetic and structural analyses revealed that putative OtCDPK proteins are closely related to CDPKs from other Chlorophytes. We functionally characterised the first marine picophytoeukaryote CDPK gene (OtCDPK1) and showed that the expression of the three OtCDPK genes is up-regulated by nitrogen depletion. We conclude that CDPK signalling pathway might have originated early in the green lineage and may play a key role in prasinophytes by sensing macronutrient changes in the marine environment.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.009
      Issue No: Vol. 118 (2017)
       
  • Six phenylalanine ammonia-lyases from Camellia sinensis: Evolution,
           expression, and kinetics
    • Authors: Yingling Wu; Wenzhao Wang; Yanzhi Li; Xinlong Dai; Guoliang Ma; Dawei Xing; Mengqing Zhu; Liping Gao; Tao Xia
      Pages: 413 - 421
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Yingling Wu, Wenzhao Wang, Yanzhi Li, Xinlong Dai, Guoliang Ma, Dawei Xing, Mengqing Zhu, Liping Gao, Tao Xia
      Phenylalanine ammonia-lyase (PAL), the branch point enzyme controlling the flow of primary metabolism into second metabolism, converts the L-phenylalanine (L-Phe) to yield cinnamic acid. Based on the sequencing data available from eight transcriptome projects, six PAL genes have been screened out, cloned, and designated as CsPALa-CsPALf. The phylogenetic tree showed that CsPALs were divided into three subgroups, PALa and PALb, PALc and PALd, and PALe and PALf. All six CsPALs exhibited indiscriminate cytosolic locations in epidermis cells and mesophyll cells. Then, the expression profiles of six PAL genes were qualitatively investigated and they displayed tissue-/induced-expression specificity in several tissues or under different exogenous treatments. Furthermore, in vitro enzymatic assays showed that all six recombinant proteins were characterized by the strict substrate specificity toward L-Phe, but no activity toward L-Tyr, and they displayed subtle differences in kinetics and enzymatic properties. These results indicate that CsPALs play both distinct and overlapping roles in plant growth and responses to environmental cues.
      Graphical abstract image

      PubDate: 2017-07-21T20:29:33Z
      DOI: 10.1016/j.plaphy.2017.06.030
      Issue No: Vol. 118 (2017)
       
  • Exogenous applications of Polyamines modulate drought responses in wheat
           through osmolytes accumulation, increasing free polyamine levels and
           regulation of polyamine biosynthetic genes
    • Authors: Heba Talat Ebeed; Nemat Mohamed Hassan; Alshafei Mohammed Aljarani
      Pages: 438 - 448
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Heba Talat Ebeed, Nemat Mohamed Hassan, Alshafei Mohammed Aljarani
      Polyamines (PAs) can improve drought stress tolerance in plants; however, very limited information is available on the mechanism of action of exogenous application by different methods under drought stress in wheat. The present study investigates the mechanism through which seed priming and foliar spraying with PAs protect wheat plants from drought stress. 10 days old wheat seedlings were exposed to drought stress by withholding water alone or with 100 μM PAs solutions (putrescine, Put; spermine, Spm; and mixture of Put and Spm for 10 h seed-priming or three foliar sprays during withholding water. Drought stress impaired the wheat growth and altered the osmoprotectants, endogenous PAs levels, PAs biosynthetic genes expression and weight of 1000 grains compared to the corresponding control values. Exogenously applied PAs improved cell water status, accumulated osmoprotectants and PAs and up-regulated PAs biosynthetic genes, ADC, arginine decarboxylase; DHS, deoxyhypusine synthase; ODC, ornithine decarboxylase and SAMDC, S-adenosyl methionine decarboxylase. Put significantly regulate the endogenous PAs by both methods of application, however, Spm and mixture of Put and Spm could positively regulate the endogenous PAs and the biosynthetic gene expression by foliar spraying rather than seed priming. The data provide evidence that maintenance of water economy through stabilized cellular structure is an important strategy of drought tolerance by PAs in wheat.

      PubDate: 2017-07-28T20:41:49Z
      DOI: 10.1016/j.plaphy.2017.07.014
      Issue No: Vol. 118 (2017)
       
  • Physiological, vascular and nanomechanical assessment of hybrid poplar
           leaf traits in micropropagated plants and plants propagated from root
           cuttings: A contribution to breeding programs
    • Authors: Jaroslav Ďurkovič; Hana Husárová; Lucia Javoříková; Ingrid Čaňová; Miriama Šuleková; Monika Kardošová; Ivan Lukáčik; Miroslava Mamoňová; Rastislav Lagaňa
      Pages: 449 - 459
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Jaroslav Ďurkovič, Hana Husárová, Lucia Javoříková, Ingrid Čaňová, Miriama Šuleková, Monika Kardošová, Ivan Lukáčik, Miroslava Mamoňová, Rastislav Lagaňa
      Micropropagated plants experience significant stress from rapid water loss when they are transferred from an in vitro culture to either greenhouse or field conditions. This is caused both by inefficient stomatal control of transpiration and the change to a higher light intensity and lower humidity. Understanding the physiological, vascular and biomechanical processes that allow micropropagated plants to modify their phenotype in response to environmental conditions can help to improve both field performance and plant survival. To identify changes between the hybrid poplar [Populus tremula × (Populus × canescens)] plants propagated from in vitro tissue culture and those from root cuttings, we assessed leaf performance for any differences in leaf growth, photosynthetic and vascular traits, and also nanomechanical properties of the tracheary element cell walls. The micropropagated plants showed significantly higher values for leaf area, leaf length, leaf width and leaf dry mass. The greater leaf area and leaf size dimensions resulted from the higher transpiration rate recorded for this stock type. Also, the micropropagated plants reached higher values for chlorophyll a fluorescence parameters and for the nanomechanical dissipation energy of tracheary element cell walls which may indicate a higher damping capacity within the primary xylem tissue under abiotic stress conditions. The performance of the plants propagated from root cuttings was superior for instantaneous water-use efficiency which signifies a higher acclimation capacity to stressful conditions during a severe drought particularly for this stock type. Similarities were found among the majority of the examined leaf traits for both vegetative plant origins including leaf mass per area, stomatal conductance, net photosynthetic rate, hydraulic axial conductivity, indicators of leaf midrib vascular architecture, as well as for the majority of cell wall nanomechanical traits. This research revealed that there were no drawbacks in the leaf physiological performance which could be attributed to the micropropagated plants of fast growing hybrid poplar.

      PubDate: 2017-07-28T20:41:49Z
      DOI: 10.1016/j.plaphy.2017.07.012
      Issue No: Vol. 118 (2017)
       
  • Photosynthetic properties of spring geophytes assessed by chlorophyll
           fluorescence analysis
    • Authors: Irene Recchia; Francesca Sparla; Paolo Pupillo
      Pages: 510 - 518
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Irene Recchia, Francesca Sparla, Paolo Pupillo
      Since spring ephemerals are credited to be all “sun” species with unusually elevate photosynthesis, in contrast to shade-tolerant trees and understory geophytes with a long aboveground cycle, we examined the photosynthetic efficiency of 6 woody species, 9 long-cycle geophytes, and 8 spring ephemeral geophytes using blue flashes of increasing energy with the Imaging PAM fluorometer. Several parameters were obtained: quantum yield of electron transport (ΦETR) or of PSII (ΦPSII), maximum measured photosynthesis rate (ETRhv), maximum extrapolated rate of photosynthesis (ETRem), half-saturating photon flux density (KPAR), and in some cases photochemical (qP) and non-photochemical quenching (NPQ). Results confirm the ecological consistency of the three plant groups, with internal differences. Woody species have low ETRem and KPAR values with good ΦETR; long-cycle herbs have low ETRem and ΦETR and moderate KPAR values; spring ephemerals have elevate ΦETR, ETRem and KPAR values. The mean ETRem of ephemerals of 91 μmol m−2 s−1 exceeds that of long-cycle herbs 2.9-fold and woody species 4.8-fold, and corresponds to 19 μmol CO2 m−2 s−1 by assuming an ETR/ΦCO2 ratio of 4.7. Highest photosynthesis rates and KPAR were exhibited by five ephemerals (Eranthis, Erythronium, Narcissus, Scilla, Tulipa) with peak ETRem values equivalent to ∼40 μmol CO2 m−2 s−1 or ∼60 μmol CO2 (g Chl)−1 s−1 (“sun” species). According to a new, fluorescence based heliophily index, all trees and five long-cycle herbs were definitely “shade” species, while four long-cycle herbs and three ephemerals were intermediate shade-tolerant.

      PubDate: 2017-08-07T09:41:06Z
      DOI: 10.1016/j.plaphy.2017.07.020
      Issue No: Vol. 118 (2017)
       
  • Salt responsive physiological, photosynthetic and biochemical attributes
           at early seedling stage for screening soybean genotypes
    • Authors: D.B. Shelke; M. Pandey; G.C. Nikalje; B.N. Zaware; P. Suprasanna; T.D. Nikam
      Pages: 519 - 528
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): D.B. Shelke, M. Pandey, G.C. Nikalje, B.N. Zaware, P. Suprasanna, T.D. Nikam
      Salt stress affects all the stages of plant growth however seed germination and early seedling growth phases are more sensitive and can be used for screening of crop germplasm. In this study, we aimed to find the most effective indicators of salt tolerance for screening ten genotypes of soybean (SL-295, Gujosoya-2, PS-1042, PK-1029, ADT-1, RKS-18, KDS-344, MAUS-47, Bragg and PK-416). The principal component analysis (PCA) resulted in the formation of three different clusters, salt sensitive (SL-295, Gujosoya-2, PS-1042 and ADT-1), salt tolerant (MAUS-47, Bragg and PK-416) and moderately tolerant/sensitive (RKS-18, PK-1029 and KDS-344) suggesting that there was considerable genetic variability for salt tolerance in the soybean genotypes. Subsequently, genotypes contrasting in salt tolerance were analyzed for their physiological traits, photosynthetic efficiency and mitochondrial respiration at seedling and early germination stages under different salt (NaCl) treatments. It was found that salt mediated increase in AOX-respiration, root and shoot K+/Na+ ratio, improved leaf area and water use efficiency were the key determinants of salinity tolerance, which could modulate the net photosynthesis (carbon assimilation) and growth parameters (carbon allocation). The results suggest that these biomarkers could be can be useful for screening soybean genotypes for salt tolerance.

      PubDate: 2017-08-07T09:41:06Z
      DOI: 10.1016/j.plaphy.2017.07.013
      Issue No: Vol. 118 (2017)
       
  • Role of phenolic compounds during antioxidative responses of winter
           triticale to aphid and beetle attack
    • Authors: Paweł Czerniewicz; Hubert Sytykiewicz; Roma Durak; Beata Borowiak-Sobkowiak; Grzegorz Chrzanowski
      Pages: 529 - 540
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Paweł Czerniewicz, Hubert Sytykiewicz, Roma Durak, Beata Borowiak-Sobkowiak, Grzegorz Chrzanowski
      One of the earliest responses of plants to insects’ attack is generation of reactive oxygen species. However, the elevated level of ROS can elicit oxidative burst within plant tissues, and plants employ antioxidant systems against these radicals. Due to their chemical structures, polyphenols are able to diminish the level of ROS. Thus, we investigated the role of phenolic compounds in oxidative stress within winter triticale caused by Sitobion avenae and Oulema melanopus. It was found, that infestation by insects induced a high increase in the content of hydrogen peroxide and superoxide anion radical within resistant Lamberto cv. 24 hpi, whereas in sensitive Marko cv., an increase in H2O2 content was found within two days of aphid feeding. Moreover, resistant plants showed earlier and much greater induction of l -phenylalanine and l -tyrosine ammonia lyases and chalcone synthase activities, as well as accumulation of phenolic compounds in response to insect feeding than susceptible Marko. On the other hand, strong positive influence of hydrogen peroxide and superoxide radical contents on chalcone synthase activity and furthermore flavonoid biosynthesis was detected in the susceptible cultivar. Negative relationships between level of o-coumaric acid or flavonoid compounds and content of hydrogen peroxide or superoxide radical suggest their antioxidant capacity. Luteolin and o-coumaric acid may attend in scavenging of hydrogen peroxide, whereas quercetin, apigenin and (+)-catechin probably participate in reduction of superoxide anion radical content.
      Graphical abstract image

      PubDate: 2017-08-07T09:41:06Z
      DOI: 10.1016/j.plaphy.2017.07.024
      Issue No: Vol. 118 (2017)
       
  • Different levels of UV-B resistance in Vaccinium corymbosum cultivars
           reveal distinct backgrounds of phenylpropanoid metabolites
    • Authors: Ana Luengo Escobar; Franklin Magnum de Oliveira Silva; Patricio Acevedo; Adriano Nunes-Nesi; Miren Alberdi; Marjorie Reyes-Díaz
      Pages: 541 - 550
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Ana Luengo Escobar, Franklin Magnum de Oliveira Silva, Patricio Acevedo, Adriano Nunes-Nesi, Miren Alberdi, Marjorie Reyes-Díaz
      UV-B radiation induces several physiological and biochemical effects that can influence regulatory plant processes. Vaccinium corymbosum responds differently to UV-B radiation depending on the UV-B resistance of cultivars, according to their physiological and biochemical features. In this work, the effect of two levels of UV-B radiation during long-term exposure on the phenylpropanoid biosynthesis, and the expression of genes associated with flavonoid biosynthesis as well as the absolute quantification of secondary metabolites were studied in two contrasting UV-B-resistant cultivars (Legacy, resistant and Bluegold, sensitive). Multivariate analyses were performed to understand the role of phenylpropanoids in UV-B defense mechanisms. The amount of phenylpropanoid compounds was generally higher in Legacy than in Bluegold. Different expression levels of flavonoid biosynthetic genes for both cultivars were transiently induced, showing that even in longer period of UV-B exposure; plants are still adjusting their phenylpropanoids at the transcription levels. Multivariate analysis in Legacy indicated no significant correlation between gene expression and the levels of the flavonoids and phenolic acids. By contrast, in the Bluegold cultivar higher number of correlations between secondary metabolite and transcript levels was found. Taken together, the results indicated different adjustments between the cultivars for a successful UV-B acclimation. While the sensitive cultivar depends on metabolite adjustments to respond to UV-B exposure, the resistant cultivar also possesses an intrinsically higher antioxidant and UV-B screening capacity. Thus, we conclude that UV-B resistance involves not only metabolite level adjustments during the acclimation period, but also depends on the intrinsic metabolic status of the plant and metabolic features of the phenylpropanoid compounds.

      PubDate: 2017-08-07T09:41:06Z
      DOI: 10.1016/j.plaphy.2017.07.021
      Issue No: Vol. 118 (2017)
       
  • Nicotinamide; antioxidative and DNA hypomethylation effects in plant cells
    • Authors: Torkel Berglund; Anders Wallström; Tuong-Van Nguyen; Cecilia Laurell; Anna B. Ohlsson
      Pages: 551 - 560
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Torkel Berglund, Anders Wallström, Tuong-Van Nguyen, Cecilia Laurell, Anna B. Ohlsson
      The effects of nicotinamide (NIC) and its natural plant metabolites nicotinic acid (NIA) and trigonelline (TRIG) were studied with respect to defense in plant cell cultures. NIC and NIA could protect against oxidative stress damage caused by 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH), which generates free radicals. Damage was analyzed as DNA strand breaks in cell cultures of Pisum sativum (garden pea), Daucus carota (carrot), Populus tremula L. × P. tremuloides (hybrid aspen) and Catharanthus roseus (Madagascar periwinkle), monitored by single cell gel electrophoresis (comet assay), and assays of cell leakage in C. roseus. The activities of aconitase and fumarase enzymes, which have key roles in energy metabolism, were analyzed in P. sativum cultures after treatment with NIC or NIA. Aconitase activity was increased by NIA, and fumarase activity was increased by both compounds. These compounds were shown to promote glutathione metabolism in P. sativum cultures, and NIC was shown to have a global DNA hypomethylating effect. Neither TRIG nor poly(ADP-ribose) polymerase (PARP) inhibitor 3-aminobenzamide offered any protection against DNA damage or cell leakage, nor did they promote aconitase or fumarase activities, or glutathione metabolism. By this broad approach addressing multiple biochemical factors and different plant species, we demonstrate that NIC and NIA protect plant cells from oxidative stress, and that NIC clearly exerts an epigenetic effect; decreased DNA methylation. This indicates that these compounds have important roles in the regulation of metabolism in plant cells, especially in connection to stress.

      PubDate: 2017-08-07T09:41:06Z
      DOI: 10.1016/j.plaphy.2017.07.023
      Issue No: Vol. 118 (2017)
       
  • In situ immobilization of Cd by organic amendments and their effect on
           antioxidant enzyme defense mechanism in mung bean (Vigna radiata L.)
           seedlings
    • Authors: Pia Muhammad Adnan Ramzani; Mark S. Coyne; Shazia Anjum; Waqas-ud-Din Khan; Muhammad Iqbal
      Pages: 561 - 570
      Abstract: Publication date: September 2017
      Source:Plant Physiology and Biochemistry, Volume 118
      Author(s): Pia Muhammad Adnan Ramzani, Mark S. Coyne, Shazia Anjum, Waqas-ud-Din Khan, Muhammad Iqbal
      In situ immobilization of Cd is desirable due to the damaging effects of ex situ remediation techniques on soil. In this greenhouse study, the role of biochar (BC), chitosan (CH), and green waste (GW) was studied for in-situ Cd immobilization and alleviating Cd toxicity in mung bean seedlings. Amendments were applied at rates of 0.5% and 1% (w/w). The minimum mean value of Cd, in root, shoot, and soil (DTPA-Cd) (12.2, 4.7, and 0.7 mg kg−1, respectively), occurred in the Cd + 1% CH treatment compared to all Cd amended treatments. Shoot dry weight (21%) increased significantly in Cd + 1% BC amended soil compared to the control. Reactive oxygen species were affected significantly, with the lowest increased value of hydrogen peroxide (4%) in the Cd + 1% CH treatment while the minimum increase in the value of superoxide (O2 •–) occurred in the Cd + 1% BC soil compared to the control. Malondialdehyde (20%) increased lowest with Cd + 1% CH treatment. Protein, ascorbate (AsA) contents, and catalase (CAT) activity increased the most (3, 2, and 15%, respectively) in the Cd + 1% BC treatment while dehydroascorbate reductase (DHAR) and superoxide dismutase (SOD) activity increased the most (9 and 234%, respectively) in the Cd + 1% CH soil compared to the control. Glutathione reductase (GR), ascorbate peroxidase (APX), and glutathione peroxidase (GPX), activity were reduced the most in the Cd + 1.0% BC treatment while dehydroascorbate (DHA) and glutathione S-transferase (GST) activity decreased the most in the Cd + 1% CH soil. Overall, in situ immobilization by amendments improved growth and antioxidant defense mechanisms of mung bean seedlings and was reflected by tolerance to Cd-toxicity.

      PubDate: 2017-08-07T09:41:06Z
      DOI: 10.1016/j.plaphy.2017.07.022
      Issue No: Vol. 118 (2017)
       
  • Abscisic acid treatment alleviates cadmium toxicity in purple flowering
           stalk (Brassica campestris L. ssp. chinensis var. purpurea Hort.)
           seedlings
    • Authors: Guoming Shen; Jiankang Niu; Zhenxu Deng
      Abstract: Publication date: Available online 20 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Guoming Shen, Jiankang Niu, Zhenxu Deng
      The aim of this research was to investigate how exogenous abscisic acid (ABA) alleviates cadmium (Cd) toxicity in purple flowering stalk (Brassica campestris L. ssp. chinensis) and evaluate whether it could be a potential choice for phytoremediation. Purple flowering stalk seedlings were cultivated in a hydroponic system with Cd at various concentrations (0–100 μmol L−1) as controls and Cd plus ABA as the treatment in the growth media. The soluble proteins, chlorophyll contents and the activity of the antioxidant enzyme system were determined by previously established biochemical methods. The contents of soluble protein and chlorophyll, and the activities of superoxide dismutase (SOD, EC 1. 15.1.1), peroxidase (POD, EC 1.11.1.7), ascorbic peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.8.1.7) and superoxide anion (O2·-) increased with the increase of external Cd concentrations, and then decreased in both Cd and Cd+ABA treatments, with higher activities of enzymes but lower level of O2·- in Cd+ABA than those in Cdonly treatments. It indicated that a stress adaptation mechanism was employed at lower Cd concentrations. The contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2), increased with the increase of Cd concentrations in the growth medium, with the highest levels in the treatment of 100 μmol L−1 Cd with lower levels in respective Cd+ABAtreatments than the Cd only treatmetns. Plants treated with 100 μmol L−1 Cd plus ABA showed a 60% decrease in Cd content in the leaves but a 259% increase in Cd content in the roots. In summary, exogenous ABA might alleviate Cd toxicity in purple flowering stalk mainly by reducing the reactive oxygen species (ROS) though activing the antioxidant enzyme system and accumulating more Cd in roots.

      PubDate: 2017-07-21T20:29:33Z
      DOI: 10.1016/j.plaphy.2017.07.018
       
  • Plant growth and resistance promoted by Streptomyces spp. in tomato
    • Authors: Maila P. Dias; Matheus S. Bastos; Vanessa B. Xavier; Eduardo Cassel; Leandro V. Astarita; Eliane R. Santarém
      Abstract: Publication date: Available online 20 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Maila P. Dias, Matheus S. Bastos, Vanessa B. Xavier, Eduardo Cassel, Leandro V. Astarita, Eliane R. Santarém
      Plant Growth Promoting Rhizobacteria (PGPR) represent an alternative to improve plant growth and yield as well as to act as agents of biocontrol. This study characterized isolates of Streptomyces spp. (Stm) as PGPR, determined the antagonism of these isolates against Pectobacterium carotovorum subsp. brasiliensis (Pcb), evaluated the ability of Stm on promoting growth and modulating the defense-related metabolism of tomato plants, and the potential of Stm isolates on reducing soft rot disease in this species. The VOC profile of Stm was also verified. Promotion of plant growth was assessed indirectly through VOC emission and by direct interaction with Stm isolates in the roots. Evaluation of soft rot disease was performed in vitro on plants treated with Stm and challenged with Pcb. Enzymes related to plant defense were then analyzed in plants treated with three selected isolates of Stm, and PM1 was chosen for further Pcb-challenging experiment. Streptomyces spp. isolates displayed characteristics of PGPR. PM3 was the isolate with efficient antagonism against Pcb by dual-culture. Most of the isolates promoted growth of root and shoot of tomato plants by VOC, and PM5 was the isolate that most promoted growth by direct interaction with Stm. Soft rot disease and mortality of plants were significantly reduced when plants were treated with StmPM1. Modulation of secondary metabolism was observed with Stm treatment, and fast response of polyphenoloxidases was detected in plants pretreated with StmPM1 and challenged with Pcb. Peroxidase was significantly activated three days after infection with Pcb in plants pretreated with StmPM1. Results suggest that Streptomyces sp. PM1 and PM5 have the potential to act as PGPR.
      Graphical abstract image

      PubDate: 2017-07-21T20:29:33Z
      DOI: 10.1016/j.plaphy.2017.07.017
       
  • Wheat and rye genome confer specific phytohormone profile features and
           interplay under water stress in two phenotypes of triticale
    • Authors: Tomasz Hura; Michał Dziurka; Katarzyna Hura; Agnieszka Ostrowska; Kinga Dziurka; Joanna Gadzinowska
      Abstract: Publication date: Available online 19 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Tomasz Hura, Michał Dziurka, Katarzyna Hura, Agnieszka Ostrowska, Kinga Dziurka, Joanna Gadzinowska
      The aim of the experiment was to determine phytohormone profile of triticale and quality-based relationships between the analyzed groups of phytohormones. The study involved two triticale phenotypes, a long-stemmed one and a semi-dwarf one with Dw1 gene, differing in mechanisms of acclimation to drought and controlled by wheat or rye genome. Water deficit in the leaves triggered a specific phytohormone response in both winter triticale phenotypes attributable to the dominance of wheat (semi-dwarf cultivar) or rye (long-stemmed cultivar) genome. Rye genome in long-stemmed triticale was responsible for specific increase (tillering: gibberellic acid; heading: N6-isopentenyladenine, trans-zeatin-9-riboside, cis-zeatin-9-riboside; flowering: N6-isopentenyladenine, indolebutyric acid, salicylic acid) or decrease (heading: trans-zeatin) in the content of some phytohormones. Wheat genome in semi-dwarf triticale controlled a specific increase in trans-zeatin content at heading and anthesis in gibberellin A1 during anthesis. The greatest number of changes in the phytohormone levels was observed in the generative phase. In both triticale types, the pool of investigated phytohormones was dominated by abscisic acid and gibberellins. The semi-dwarf cultivar with Dw1 gene was less sensitive to gibberellins and its mechanisms of acclimation to water stress were mainly ABA-dependent. An increase in ABA and gibberellins during drought and predominance of these hormones in the total pool of analyzed phytohormones indicated their equal share in drought acclimation mechanisms in long-stemmed cultivar.

      PubDate: 2017-07-21T20:29:33Z
      DOI: 10.1016/j.plaphy.2017.07.016
       
  • Grapevine tissues and phenology differentially affect soluble
           carbohydrates determination by capillary electrophoresis
    • Authors: Daniela Moreno; Federico Berli; Rubén Bottini; Patricia N. Piccoli; María F. Silva
      Abstract: Publication date: Available online 8 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Daniela Moreno, Federico Berli, Rubén Bottini, Patricia N. Piccoli, María F. Silva
      Soluble carbohydrates distribution depends on plant physiology and, among other important factors, determines fruit yield and quality. In plant biology, the analysis of sugars is useful for many purposes, including metabolic studies. Capillary electrophoresis (CE) proved to be a powerful green separation technique with minimal sample preparation, even in complex plant tissues, that can provide high-resolution efficiency. Matrix effect refers to alterations in the analytical response caused by components of a sample other than the analyte of interest. Thus, the assessment and reduction of the matrix factor is fundamental for metabolic studies in different matrices. The present study evaluated the source and levels of matrix effects in the determination of most abundant sugars in grapevine tissues (mature and young leaves, berries and roots) at two phenological growth stages. Sucrose was the sugar that showed the least matrix effects, while fructose was the most affected analyte. Based on plant tissues, young leaves presented the smaller matrix effects, irrespectively of the phenology. These changes may be attributed to considerable differences at chemical composition of grapevine tissues with plant development. Therefore, matrix effect should be an important concern for plant metabolomics.
      Graphical abstract image

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.010
       
  • Regulation of proline biosynthesis and resistance to drought stress in two
           barley (Hordeum vulgare L.) genotypes of different origin
    • Authors: Hanna Bandurska; Justyna Niedziela; Małgorzata Pietrowska-Borek; Katarzyna Nuc; Tamara Chadzinikolau; Dominika Radzikowska
      Abstract: Publication date: Available online 8 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Hanna Bandurska, Justyna Niedziela, Małgorzata Pietrowska-Borek, Katarzyna Nuc, Tamara Chadzinikolau, Dominika Radzikowska
      Drought is considered the main abiotic stress factor that inhibits growth of crop plants (including barley), limiting yield in many regions worldwide. Predicted climate changes show that in future the frequency and intensity of drought events will rise, so crops that are resistant to this stress are in demand. One of the adaptive metabolic responses to drought is the accumulation of proline. The aim of this study was to examine the effect of 10-day drought on tissue dehydration and proline biosynthesis in leaves as well as in roots of barley genotypes of different origin: the Syrian breeding line Cam/B1/CI and the German cultivar Maresi. The involvement of Δ1 pyrroline-5-carboxylate synthetase (P5CS), the expression of the P5CS gene and ABA in proline synthesis under drought were also studied. Finally, we examined the resistance of tested genotypes to applied drought using chlorophyll fluorescence parameters and above-ground dry matter accumulation. Drought caused a gradual decrease of water content and an increase of proline and ABA content in roots and leaves of both genotypes. A statistically significant positive correlation between proline accumulation and activity of P5CS was also revealed. The skyrocketing increase of P5CS activity and proline accumulation was proceeded by transcriptional up-regulation of P5CS. The relationships between changes in P5CS expression, P5CS activity and ABA content show that the latter compound is involved in drought-induced proline synthesis at the transcription and enzyme activity level. The examined barley genotypes were equally resistant to applied moderate drought stress regardless of the differences in the level of proline accumulated.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.006
       
  • Photosynthetic parameters and redox homeostasis of Artemisia santonica L.
           under conditions of Elton region
    • Authors: Olga Rozentsvet; Anatoly Kosobryukhov; Ilya Zakhozhiy; Galina Tabalenkova; Viktor Nesterov; Ilena Bogdanova
      Abstract: Publication date: Available online 6 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Olga Rozentsvet, Anatoly Kosobryukhov, Ilya Zakhozhiy, Galina Tabalenkova, Viktor Nesterov, Ilena Bogdanova
      Structural and functional parameters and redox homeostasis in leaves of Artemisia santonica L. under environment conditions of Elton lake (the southeast region of the European part of Russia) were measured. The highest photosynthetic apparatus (PA) activity in A. santonica leaves on CO2 gas exchange as well as the highest content of green pigments was observed in the morning. Maximum share of violaxanthin cycle key pigments – zeaxanthin (Zx) and antheraxanthin (Ax) was observed in the afternoon and decreased in the evening. Lipids/chlorophyll (Chl) ratio increased in the evening due to the decrease in Chl concentration, and content of linolenic acid (С18:3n3) was decreased in the middle of the day. The content of TBA-reacting products increased 1.4-fold in the middle of the day, and decreased approximately 2-fold in the evening. The decrease of the activity was observed in diurnal dynamics of superoxide dismutase (SOD) and polyphenol oxidase (PPO). Increased accumulation of phenols and flavonoids, as well as free amino acids (FAA) in A. santonica leaves was observed in the middle of the day. Thus, the ability of A. santonica plants to resist the soil salinization, high levels of solar illumination and temperature consists of a number of protectively-adaptive reactions of metabolic and photosynthetic control.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.005
       
  • Towards a better understanding of protein changes in common bean under
           drought: A case study of N-glycoproteins
    • Authors: Tanja Zadražnik; Anders Moen; Wolfgang Egge-Jacobsen; Vladimir Meglič; Jelka Šuštar-Vozlič
      Abstract: Publication date: Available online 5 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Tanja Zadražnik, Anders Moen, Wolfgang Egge-Jacobsen, Vladimir Meglič, Jelka Šuštar-Vozlič
      Drought is one of the major abiotic stress conditions limiting crop growth and productivity. Glycosylation of proteins is very important post-translational modification that is involved in many physiological functions and biological pathways. To understand the involvement of N-glycoproteins in the mechanism of drought response in leaves of common bean, a proteomic approach using lectin affinity chromatography, SDS-PAGE and LC-MS/MS was applied. Quantification of N-glycoproteins was performed using MaxQuant with a label free quantification approach. Thirty five glycoproteins were changed in abundance in leaves of common bean under drought. The majority of these proteins were classified into functional groups that include cell wall processes, defence/stress related proteins and proteins related to proteolysis. Beta-glucosidase showed the highest increase in abundance among proteins involved in cell wall metabolism, suggesting its role in cell wall modification under drought stress. These results fit with the general concept of the stress response in plants and suggest that drought stress might affect biochemical metabolism in the cell wall. The structures of N-glycans were determined manually from spectra, where structures of high mannose, complex and hybrid types of N-glycans were found. The present study provided an insight into the glycoproteins related to drought stress in common bean at the proteome level, which is important for further understanding of molecular mechanisms of drought response in this important legume.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.004
       
  • Labeled Azospirillum brasilense wild type and excretion-ammonium strains
           in association with barley roots
    • Authors: Adrian Richard Schenberger Santos; Rafael Mazer Etto; Rafaela Wiegand Furmam; Denis Leandro de Freitas; Karina Freire d’Eça Nogueira Santos; Emanuel Maltempi de Souza; Fábio de Oliveira Pedrosa; Ricardo Antônio Ayub; Maria Berenice Reynaud Steffens; Carolina Weigert Galvão
      Abstract: Publication date: Available online 4 July 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Adrian Richard Schenberger Santos, Rafael Mazer Etto, Rafaela Wiegand Furmam, Denis Leandro de Freitas, Karina Freire d’Eça Nogueira Santos, Emanuel Maltempi de Souza, Fábio de Oliveira Pedrosa, Ricardo Antônio Ayub, Maria Berenice Reynaud Steffens, Carolina Weigert Galvão
      Soil bacteria colonization in plants is a complex process, which involves interaction between many bacterial characters and plant responses. In this work, we labeled Azospirillum brasilense FP2 (wild type) and HM053 (excretion-ammonium) strains by insertion of the reporter gene gusA-kanamycin into the dinitrogenase reductase coding gene, nifH, and evaluated bacteria colonization in barley (Hordeum vulgare). In addition, we determined inoculation effect based on growth promotion parameters. We report an uncommon endophytic behavior of A. brasilense Sp7 derivative inside the root hair cells of barley and highlight the promising use of A. brasilense HM053 as plant growth-promoting bacterium.

      PubDate: 2017-07-11T07:18:08Z
      DOI: 10.1016/j.plaphy.2017.07.003
       
  • Characterization of iron deficiency symptoms in grapevine (Vitis spp.)
           leaves by reflectance spectroscopy
    • Authors: Laura Rustioni; Daniele Grossi; Lucio Brancadoro; Osvaldo Failla
      Abstract: Publication date: Available online 30 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Laura Rustioni, Daniele Grossi, Lucio Brancadoro, Osvaldo Failla
      The work aims at the description of the iron deficiency symptoms in grapevine leaves by reflectance spectroscopy at the plant and leaf levels. 5 genotypes of Vitis spp. were selected and grown in hydroponic conditions with and without iron supply. 450 spectra were collected among basal, young and apical leaves, as well as veins and interveinal areas. Iron deficiency produced significant and characteristic modifications in the pigment accumulation, proportion and distribution in plants. Basal leaves resulted to have higher concentrations of photosynthetic pigments in stressed plants with respect to the control, probably due to compensation effects. Iron deficient plants had lower chlorophyll concentrations in young and apical leaves. In the apical zone, also the relative composition of pigments appeared to be modified, explaining the reddish-yellowish apex appearance of iron deficient vines. Finally, the pigment distribution along the shoot characterized the symptoms, as well as the spectral variations among veins and interveinal areas. These results could support future applications in vineyard management (e.g.: symptom identification and detection; precision fertilization) as well as breeding programs for new rootstock selections (e.g.: fast screenings of seedlings).

      PubDate: 2017-07-01T16:44:52Z
      DOI: 10.1016/j.plaphy.2017.06.031
       
  • 5-Aminolevulinic acid improves DNA damage and DNA Methylation changes in
           deltamethrin-exposed Phaseolus vulgaris seedlings
    • Authors: Mahmut Sinan Taspinar; Murat Aydin; Esra Arslan; Muhammet Yaprak; Guleray Agar
      Abstract: Publication date: Available online 21 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Mahmut Sinan Taspinar, Murat Aydin, Esra Arslan, Muhammet Yaprak, Guleray Agar
      Deltamethrin, synthetic type II pyrethroid, is one of the most widely used pesticide in agriculture. Intense use of deltamethrin can cause permanant or temporary damages in nontarget plant species. In this study, we aimed to determine DNA methylation change and DNA damage level in Phaseolus vulgaris seedlings subjected to different concentrations of deltamethrin (0.02, 0.1 and 0.5 ppm). Coupled Restriction Enzyme Digestion-Random Amplification (CRED-RA) was performed to analyze the changes of DNA methylation as well as Randomly Amplified Polymorphic DNA (RAPD) was used for genotoxic influences estimation and genomic stability. The results showed that deltamethrin caused to increase in RAPD profile changes (DNA damage) and reduce in Genomic Template Stability (GTS). GTS declined markedly in relation to increasing concentration of deltamethrin applied. The lowest GTS value (71.4%) observed in 0.5 ppm deltamethrin treatment. Also, DNA hypermethylation was occurred in all treatments. Moreover, alleviative effect of 5-aminolevulinic acid (ALA) (20, 40 and 80 mg/l), one of the plant growth regulators, was tested against the 0.5 ppm deltamethrin. Adverse effects of deltamethrin on GTS decreased after ALA treatments, especially 20 mg/l concentration. As a result, we concluded that ALA has a strong anti-genotoxic agent against deltamethrin and it could be an alternative chemical to reduce genetic damage in plants under deltamethrin stress conditions.

      PubDate: 2017-06-21T20:51:55Z
      DOI: 10.1016/j.plaphy.2017.06.026
       
  • Physio-biochemical basis of iron-sulfide nanoparticle induced growth and
           seed yield enhancement in B. juncea
    • Authors: Madhu Rawat; Rajeev Nayan; Bhawana Negi; M.G.H. Zaidi; Sandeep Arora
      Abstract: Publication date: Available online 20 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Madhu Rawat, Rajeev Nayan, Bhawana Negi, M.G.H. Zaidi, Sandeep Arora
      Metal nanoparticles have been reported to influence plant growth and productivity. However, the molecular mechanisms underlying the effects have not been completely understood yet. Current work describes the physio-biochemical basis of iron sulfide nanoparticle induced growth and yield enhancement in Brassica juncea. Iron sulfide nanoparticles (0, 2, 4, 6, 8 and 10 ppm) were used for foliar treatment of B. juncea at 30, 45 and 60 days after sowing, under field conditions. Foliar treatment of 4 ppm iron sulfide nanoparticle solution at 30 days after sowing brought maximal enhancement in agronomic attributes of the treated plants. Results of assays i.e. total chlorophyll, electrolyte leakage, Malondialdehyde (MDA), proline, H2O2 and antioxidant enzyme activities indicated the benign effect of iron sulfide nanoparticles on plants. Consequently, improved redox status of the treated plants, enabled them to assimilate higher photosynthate. The augmentation in growth and seed yield in iron sulfide nanoparticle treated plants was amply supported by activation of RUBISCO small subunit (rubisco S), RUBISCO large subunit (rubisco L), glutamine synthetase (gs) and glutamate synthase (gogat) genes. Thus, iron sulfide nanoparticle induced growth and yield enhancement is proposed to be mediated through activation of carbon and nitrogen assimilatory pathways at specific growth stage. The iron content in the leaves and root tissues of the treated plants was also significantly improved.

      PubDate: 2017-06-21T20:51:55Z
      DOI: 10.1016/j.plaphy.2017.06.021
       
  • Alterations of growth, antioxidant system and gene expression in
           Stylosanthes guianensis during Colletotrichum gloeosporioides infection
    • Authors: Hui Wang; Zhijian Chen; Guodao Liu; Changjun Bai; Hong Qiu; Yanxing Jia; Lijuan Luo
      Abstract: Publication date: Available online 20 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Hui Wang, Zhijian Chen, Guodao Liu, Changjun Bai, Hong Qiu, Yanxing Jia, Lijuan Luo
      Anthracnose caused by Colletotrichum gloeosporioides is one of the most destructive fungal diseases of many plants, including stylo (Stylosanthes spp.), which is an important tropical forage legume. Although C. gloeosporioides-caused anthracnose is the major constraint limiting the growth and yield of stylo, little information is available regarding the responses of stylo during the infection process of this pathogen. This study investigated the changes in growth, the antioxidant system and gene expression in stylo in response to C. gloeosporioides treatment. Negative effects of C. gloeosporioides were observed in inoculated stylo plants, as reflected by the formation of necrotic disease lesions and the decrease in shoot fresh weight. Reactive oxygen species (ROS) accumulation increased in stylo leaves during the C. gloeosporioides infection process. The activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX) and glutathione reductase (GR), as well as the concentrations of the antioxidant compounds ascorbate (AsA) and glutathione (GSH), increased in leaves under C. gloeosporioides treatment. Furthermore, transcriptional analysis showed that the expression of stress response genes, including NADPH oxidase (Nox), thioredoxin (Thi), pathogenesis related genes (PR1 and PR5), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), chalcone synthase (CHS) and chitinase (Cht), was differentially enhanced in stylo leaves by C. gloeosporioides. Taken together, this study provides novel information regarding the alterations during the infection process of C. gloeosporioides in stylo at the levels of antioxidant system and gene expression.

      PubDate: 2017-06-21T20:51:55Z
      DOI: 10.1016/j.plaphy.2017.06.024
       
  • Comparative proteomic and metabolomic studies between Prunus persica
           genotypes resistant and susceptible to Taphrina deformans suggest a
           molecular basis of resistance
    • Authors: Camila Goldy; Laura A. Svetaz; Claudia A. Bustamante; Marco Allegrini; Gabriel H. Valentini; María F. Drincovich; Alisdair R. Fernie; María V. Lara
      Abstract: Publication date: Available online 17 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Camila Goldy, Laura A. Svetaz, Claudia A. Bustamante, Marco Allegrini, Gabriel H. Valentini, María F. Drincovich, Alisdair R. Fernie, María V. Lara
      The worldwide-distributed leaf peach curl disease is caused by the biotroph Taphrina deformans. To characterize the plant-fungus interaction, resistant and susceptible Prunus persica genotypes grown in the orchard were studied. Asymptomatic leaves were tested for fungal presence. In all resistant leaves analyzed the fungus was not detected. Conversely, leaves from the susceptible genotype were categorized according to the presence or absence of the pathogen. Comparative metabolomic analysis disclosed the metabolite composition associated with resistant and susceptible interactions, and of compounds involved in fungal growth inhibition such as chlorogenic acid, whose in vitro antifungal activity was verified in this work. Differential proteome studies revealed that chloroplasts are important site of plant defense responses against T. deformans. Members of the Bet-v1-like family protein differentially responded to the pathogen. Extracellular pathogenesis-related proteins, evaluated by qRT-PCR, and an enone oxidoreductase are constitutively present in leaves of resistant trees and could be related to fungal resistance. This study is a global view of the changes in the metabolome, proteome and transcripts related to plant defense in naturally infected leaves of susceptible plants during the asymptomatic stage. Additionally, it provides clues to the successful molecular mechanisms operating in resistant plants, which neither develop the disease nor harbor the pathogen.

      PubDate: 2017-06-21T20:51:55Z
      DOI: 10.1016/j.plaphy.2017.06.022
       
  • Suppression of the MADS-box gene SlMBP8 accelerates fruit ripening of
           tomato (Solanum lycopersicum)
    • Authors: Wencheng Yin; Zongli Hu; Baolu Cui; Xuhu Guo; Jingtao Hu; Zhiguo Zhu; Guoping Chen
      Abstract: Publication date: Available online 15 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Wencheng Yin, Zongli Hu, Baolu Cui, Xuhu Guo, Jingtao Hu, Zhiguo Zhu, Guoping Chen
      MADS-box genes encode important transcription factors that are involved in many biological processes of plants, including fruit ripening. In our research, a MADS-box gene, SlMBP8, was identified, and its tissue-specific expression profiles were analysed. SlMBP8 was highly expressed in fruits of the B+4 stage, in senescent leaves and in sepals. To further characterize its function, an RNA interference (RNAi) expression vector of SlMBP8 was constructed and transferred into tomato. In the transgenic plants, the ripening of fruits was shortened by 2–4 days compared to that of wild type. At the same time, carotenoids accumulated to higher levels and the expression of phytone synthase 1 (PSY1), phytoene desaturase (PDS) and ς-carotene desaturase (ZDS) was enhanced in RNAi fruits. The transgenic fruits and seedlings showed more ethylene production compared with that of the wild type. Furthermore, SlMBP8-silenced seedlings displayed shorter hypocotyls due to higher endogenous ethylene levels, suggesting that SlMBP8 may modulates the ethylene triple response negatively. A yeast two-hybrid assay indicated that SlMBP8 could interact with SlMADS-RIN. Besides, the expression of ethylene-related genes, including ACO1, ACO3, ACS2, ERF1, E4 and E8, was simultaneously up-regulated in transgenic plants. In addition, SlMBP8-silenced fruits showed higher ethylene production, suggesting that suppressed expression of SlMBP8 promotes carotenoid and ethylene biosynthesis. In addition, the fruits of transgenic plants displayed more rapid water loss and decreased storability compared to wild type, which was due to the significantly induced expressions of cell wall metabolism genes such as PG, EXP, HEX, TBG4, XTH5 and XYL. These results suggest that SlMBP8 plays an important role in fruit ripening and softening.

      PubDate: 2017-06-16T20:46:04Z
      DOI: 10.1016/j.plaphy.2017.06.019
       
  • Beneficial effects of melatonin in overcoming drought stress in wheat
           seedlings
    • Authors: Guibin Cui; Xiaoxiao Zhao; Shudong Liu; Fengli Sun; Chao Zhang; Yajun Xi
      Abstract: Publication date: Available online 15 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Guibin Cui, Xiaoxiao Zhao, Shudong Liu, Fengli Sun, Chao Zhang, Yajun Xi
      Melatonin plays an important role in abiotic stress in plant, but its role in wheat drought tolerance is less known. To verify its role, wheat seedlings (Triticum aestivum L. ‘Yan 995’) at 60% and 40% of field capacity were treated with 500 μM melatonin in this study. Melatonin treatment significantly enhanced the drought tolerance of wheat seedlings, as demonstrated by decreased membrane damage, more intact grana lamella of chloroplast, higher photosynthetic rate, and maximum efficiency of photosystem II, as well as higher cell turgor and water holding capacity in melatonin-treated seedlings. Besides, melatonin markedly decreased the content of hydrogen peroxide and superoxide anion in melatonin-treated seedlings, which is attributed to the increased total antioxidant capacity, GSH and AsA contents, as well as enzyme activity including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione peroxidase (GPX), and glutathione transferase (GST). The GSH-AsA related genes including APX, MDHAR, and DHAR were commonly upregulated by melatonin and correlated to the antioxidant enzyme activity as well as the content of GSH and AsA, indicating that the increase of GSH and AsA was attributed to the expression of these genes. Our result confirmed the mitigation potential of melatonin in drought stress and certain mechanisms of melatonin-induced GSH and AsA accumulation, which could deepen our understanding of melatonin-induced drought tolerance in wheat.

      PubDate: 2017-06-16T20:46:04Z
      DOI: 10.1016/j.plaphy.2017.06.014
       
  • Effects of salinity and short-term elevated atmospheric CO2 on the
           chemical equilibrium between CO2 fixation and photosynthetic electron
           transport of Stevia rebaudiana Bertoni
    • Authors: Sayed Hussin; Nicole Geissler; Mervat M.M. El-Far; Hans-Werner Koyro
      Abstract: Publication date: Available online 15 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Sayed Hussin, Nicole Geissler, Mervat M.M. El-Far, Hans-Werner Koyro
      The effect of water salinity on plant growth and photosynthetic traits of Stevia rebaudiana was investigated to determine its level and mechanisms of salinity tolerance. It was also attempted to assess how short-term elevated CO2 concentration would influence the boundaries and mechanisms of its photosynthetic capacity. The plants were grown in gravel/hydroponic system under controlled greenhouse conditions and irrigated with four different salinity levels (0, 25, 50 and 100 mol m−3NaCl). Low salinity did not significantly alter the plant fresh weight, which was substantially decreased by 67% at high salinity treatment. Salinity tolerance threshold was reached at 50 mol m−3 NaCl while C50 was between 50 and 100 mol m−3 NaCl, indicating that S. rebaudiana is a moderate salt tolerant species. Salt-induced growth reduction was apparently linked to a significant decline of about 47% in the photosynthetic rates (Anet) at high salinity treatment, leading consequently to a disequilibrium between CO2-assimilation and electron transport rates (indicated by enhanced ETRmax/Agross ratio). Elevated atmospheric CO2 enhanced CO2-assimilation rates by 65% and 80% for control and high-salt-stressed plants respectively, likely due to significant increases in intercellular CO2 concentration (indicated by enhanced Ci/Ca). The priority for Stevia under elevated atmospheric CO2 was not to save water but to maximize photosynthesis so that the PWUE was progressively improved and the threat of oxidative stress was diminished (decline in ETRmax/Agross ratio). The results imply that elevated CO2 level could ameliorate some of the detrimental effects of salinity, conferring higher tolerance and survival of S. rebaudiana, a highlydesired feature with the forthcoming era of global changes.

      PubDate: 2017-06-16T20:46:04Z
      DOI: 10.1016/j.plaphy.2017.06.017
       
  • Hormonal profile and the role of cell expansion in the germination control
           of Cerrado biome palm seeds
    • Authors: Daiane Souza Dias; Leonardo Monteiro Ribeiro; Paulo Sérgio Nascimento Lopes; Sergi Munné-Bosch; Queila Souza Garcia
      Abstract: Publication date: Available online 15 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Daiane Souza Dias, Leonardo Monteiro Ribeiro, Paulo Sérgio Nascimento Lopes, Sergi Munné-Bosch, Queila Souza Garcia
      Little information is currently available concerning the mechanisms controlling palm seed germination. We compared the anatomical and physiological aspects of seeds of two neotropical palm species showing different levels of dormancy. The seeds of Attalea vitrivir and Butia capitata were evaluated for the endogenous contents of hormones (ABA, GAs, CKs, BRs, IAA, JA, SA and the ethylene precursor ACC) in their cotyledonary petiole and operculum (structures involved in germination control), the force necessary to displace the operculum, endo-β-mannanase activities, and embryo cell elongation. The analyses were carried out on with intact dry and imbibed seeds as well as with seeds with the operculum mechanically removed, 2, 5 and 10 days after sowing. The germinabilities of the intact seeds of A. vitrivir and B. capitata were 68% and 3%, respectively; the removal of the operculum increased germination to more than 90% in both species. Reductions of ABA and increases in GAs contents coincided with cell elongation, although there is no evidence that hormonal balance and endo-β-mannanase activity are involved in operculum weakening. The ratio between the embryo length and the force required for operculum displacement (EL/OF) was found to be 1.9 times greater in A. vitrivir than in B. capitata, which means that very small elongations in each cell would be sufficient to promote germination, resulting in a lower level of dormancy in the former species. EL/OF and cell growth control are therefore important for defining dormancy level in palm seeds.

      PubDate: 2017-06-16T20:46:04Z
      DOI: 10.1016/j.plaphy.2017.06.015
       
  • In vitro protein synthesis of sugar beet (Beta vulgaris) and maize (Zea
           
    • Authors: Franziska Faust; Sven Schubert
      Abstract: Publication date: Available online 15 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Franziska Faust, Sven Schubert
      The substitution of potassium ions (K+) by sodium ions (Na+) in the nutrition of plants is restricted. It was shown earlier that net protein synthesis is the process which is most sensitive to the substitution of K+ by Na+ in young sugar beet. We hypothesized that the activity of ribosomes is inhibited by the substitution. This hypothesis was tested in an in vitro approach. Cytosolic polysomes were isolated from growing leaves of sugar beet and maize by means of differential centrifugation. In vitro systems of both plant species were tested for functionality and comparability. Translation was quantified by the 35S-methionine incorporation in TCA-precipitable products. The effect of different substitution levels (0%, 20%, 40%, 60%, and 80% substitution of K+ by Na+) on in vitro translation was measured. Translation by polysomes of both plant species was significantly inhibited by the substitution. However, the translation by maize polysomes was more negatively affected by the substitution. A significant decrease in the translation by maize polysomes was observed already when 20% of K+ were replaced by Na+, whereas in the case of sugar beet, the translation was inhibited firstly at the substitution level of 40%. The in vitro results show that the process of translation itself is disturbed by the substitution and indicate a higher tolerance of sugar beet polysomes to increased Na+ concentrations and Na+/K+ ratios compared to polysomes of maize. We propose that this tolerance contributes to the salt resistance of sugar beet.

      PubDate: 2017-06-16T20:46:04Z
      DOI: 10.1016/j.plaphy.2017.06.016
       
  • Biotechnological production of recombinant tissue plasminogen activator
           protein (reteplase) from transplastomic tobacco cell cultures
    • Authors: Diego Hidalgo; Maryam Abdoli Nasab; Mokhtar Jalali-Javaran; Roque Bru-Martínez; Rosa M. Cusidó; Purificación Corchete; Javier Palazon
      Abstract: Publication date: Available online 13 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Diego Hidalgo, Maryam Abdoli Nasab, Mokhtar Jalali-Javaran, Roque Bru-Martínez, Rosa M. Cusidó, Purificación Corchete, Javier Palazon
      Transplastomic plants are a system of choice for the mass production of biopharmaceuticals due to the polyploidy of the plastid genome and the low risk of pollen-mediated outcrossing because of maternal inheritance. However, as field-grown plants, they can suffer contamination by agrochemicals and fertilizers, as well as fluctuations in yield due to climatic changes and infections. Tissue-type plasminogen activator (tPA), a protein used to treat heart attacks, converts plasminogen into plasmine, which digests fibrin and induces the dissolution of fibrin clots. Recently, we obtained transplastomic tobacco plants carrying the K2S gene encoding truncated human tPA (reteplase) with improved biological activity, and confirmed the presence of the target protein in the transgenic plant leaves. Considering the advantages of plant cell cultures for biopharmaceutical production, we established a cell line derived from the K2S tobacco plants. The active form of reteplase was quantified in cultures grown in light or darkness, with production 3-fold higher in light.

      PubDate: 2017-06-16T20:46:04Z
      DOI: 10.1016/j.plaphy.2017.06.013
       
  • Bacillus subtilis affects miRNAs and flavanoids production in
           Agrobacterium-Tobacco interaction
    • Authors: Fahimeh Nazari; Naser Safaie; Bahram Mohammad Soltani; Masoud Shams-Bakhsh; Mohsen Sharifi
      Abstract: Publication date: Available online 10 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Fahimeh Nazari, Naser Safaie, Bahram Mohammad Soltani, Masoud Shams-Bakhsh, Mohsen Sharifi
      Agrobacterium tumefaciens is a very destructive plant pathogen. Selection of effective biological agents against this pathogen depends on more insight into molecular plant defence responses during the biocontrol agent-pathogen interaction. Auxin as a phytohormone is a key contributor in pathogenesis and plant defence and accumulation of auxin transport carriers are accompanied by increasing in flavonoid and miRNAs concentrations during plant interactions with bacteria. The aim of this research was molecular analysis of Bacillus subtilis (ATCC21332) biocontrol effect against A. tumefaciens (IBRC-M10701) pathogen interacting with Nicotiana tabacum plants. Tobacco plants were either treated with both or one of the challenging bacteria and the expression of miRNAs inside the plants were analysed through qRT-PCR. The results indicated that the bacterial treatments affect expression level of nta-miRNAs. In tobacco plants treated only with A. tumefaciens the expression of nta-miR393 was more than that was recorded for nta-miR167 (3.8 folds, P < 0.05 in 3dpi). While the expression level of nta-miR167 was more than the expression of nta-miR393 in other treatments including tobacco plants treated only with B. subtilis (2.1 folds, P < 0.05) and the plants treated with both of the bacteria (3.9 folds, P < 0.05) in 3 dpi. Also, the composition and concentration of rutin, myrecetin, daidzein and vitexin flavanoid derivatives were detected using HPLC and analysed according the standard curves. All of the tested flavanoid compounds were highly detected in Tobacco plants which were only challenged with A. tumefaciens. The amount of these compounds in the plants which were challenged with the B. subtilis alone, was similar to the amount recorded for the plants challenged with the both bacteria. This study suggests a relationship between the upregulation of nta-miR167, nta-miR393 and accumulation of flavanoid compounds. Overall, the expression of these miRNAs as well as flavonoid derivatives has the potential of being used as biomarkers for the interaction of B. subtilis and A. tumefaciens model system in N. tabacum.

      PubDate: 2017-06-11T20:33:30Z
      DOI: 10.1016/j.plaphy.2017.06.010
       
  • Immobilisation of barley aleurone layers enables parallelisation of assays
           and analysis of transient gene expression in single cells
    • Authors: Kinga Zór; Christina Mark; Arto Heiskanen; Claus Krogh Madsen; Martin Dufva; Jenny Emnéus; Henrik Brinch-Pedersen; Christine Finnie
      Abstract: Publication date: Available online 8 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Kinga Zór, Christina Mark, Arto Heiskanen, Claus Krogh Madsen, Martin Dufva, Jenny Emnéus, Henrik Brinch-Pedersen, Christine Finnie
      The barley aleurone layer is an established model system for studying phytohormone signalling, enzyme secretion and programmed cell death during seed germination. Most analyses performed on the aleurone layer are end-point assays based on cell extracts, meaning each sample is only analysed at a single time point. By immobilising barley aleurone layer tissue on polydimethylsiloxane pillars in the lid of a multiwell plate, continuous monitoring of living tissue is enabled using multiple non-destructive assays in parallel. Cell viability and menadione reducing capacity were monitored in the same aleurone layer samples over time, in the presence or absence of plant hormones and other effectors. The system is also amenable to transient gene expression by particle bombardment, with simultaneous monitoring of cell death. In conclusion, the easy to handle and efficient experimental setup developed here enables continuous monitoring of tissue samples, parallelisation of assays and single cell analysis, with potential for time course studies using any plant tissue that can be immobilised, for example leaves or epidermal peels.
      Graphical abstract image

      PubDate: 2017-06-11T20:33:30Z
      DOI: 10.1016/j.plaphy.2017.06.008
       
  • Photoprotection regulated by phosphorus application can improve
           photosynthetic performance and alleviate oxidative damage in dwarf bamboo
           subjected to water stress
    • Authors: Chenggang Liu; Yanjie Wang; Yanqiang Jin; Kaiwen Pan; Xingmei Zhou; Na Li
      Abstract: Publication date: Available online 8 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Chenggang Liu, Yanjie Wang, Yanqiang Jin, Kaiwen Pan, Xingmei Zhou, Na Li
      Water and nutrients, particularly phosphorus (P), are the two most limiting factors for dwarf bamboo growth in tropical and subtropical areas. Dwarf bamboo is highly sensitive to water stress and often causes severe P deficiency in its growing soils due to the characteristics of shallower roots and expeditious growth. However, little is known about its photoprotective response to soil water deficit and the underlying mechanisms regulated by P application. In this study, a completely randomized design with two factors of two water regimes (well-watered and water-stressed) and two P levels (with and without P application) was arranged to investigate this issue in dwarf bamboo (Fargesia rufa) plants. Water stress not only decreased water status and photochemical activity but also increased lipid peroxidation due to reactive oxygen species (ROS) accumulation irrespective of P application. In this case, thermal dissipation and antioxidative defense were promoted. Moreover, the role of the water−water cycle under this stress still could not be ignored because it accounted for a large proportion of total energy (J PSII). P application significantly enhanced photochemical activity accompanied by increased chlorophyll content in water-stressed plants. Meanwhile, P application remarkably reduced thermal dissipation and hardly affected photorespiration and the water−water cycle under water stress. Although P application only enhanced ascorbate (AsA) level, ROS, particularly hydrogen peroxide (H2O2), and lipid peroxidation were significantly reduced in water-stressed plants. Therefore, P application can improve the photosynthetic capacity by regulating the redistribution of energy absorbed by PSII antennae and independently activating of the H2O2-scavenging function of AsA to alleviate oxidative damage in F. rufa plants, thereby improving their survival under water stress conditions.

      PubDate: 2017-06-11T20:33:30Z
      DOI: 10.1016/j.plaphy.2017.05.022
       
  • Assessment of the phenolic profile, antimicrobial activity and oxidative
           stability of transgenic Perilla frutescens L.overexpressing tocopherol
           methyltransferase (γ-tmt) gene
    • Authors: Bimal Kumar Ghimire; Chang Yeon Yu; Ill-Min Chung
      Abstract: Publication date: Available online 7 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Bimal Kumar Ghimire, Chang Yeon Yu, Ill-Min Chung
      This study evaluated the effects of enhanced concentrations of α-tocopherol and phenolic compounds on the resistance and stability of Perilla oil in transgenic Perilla frutescens plants against various tested pathogenic bacteria by over-expressing the γ-tmt gene. The concentration of phenolic compounds in the non-transgenic samples was 9313.198 ± 18.887 μg g−1 dry weight (DW), whereas the total concentration of the transgenic samples ranged from 9118.015 ± 18.822 to 10527.612 ± 20.411 μg g−1 DW. The largest increases in phenolic compounds in the transgenic plants in comparison with the control plants were observed in gallic acid, pyrogallol, 5-sulfosalicylic acid, catechin, chlorogenic acid, vanillin, syringic acid, naringenin, salicylic acid, quercetin, o-coumaric acid, kaempferol, and hesperetin. o-coumaric and benzoic acid acid were the most abundant phenolic acids found in the transgenic plants. Gram-negative bacteria (Salmonella typhimurium) were the most susceptible microorganism against transgenic ethyl acetate extracts with lower measurement of minimum inhibitory concentration (MICs) (0.25 ± 0.03 mg/ml) at an extract concentration of 2 mg/ml in dried plant material. The same extracts were more effective against gram-positive bacteria (Bacillus subtilis) when compared to control plants with MICs values of 0.52 ± 0.02 mg/ml. The suplementation of 20 μg of α-tocopherol (1000 ppm) in combination with ethyl acetate extracts enhanced the antimicrobial activity against S. typhimurium and B. subtilis, compared to the non-transgenic plants. The acid value of transgenic Perilla oil improved by 91.2% and 35.54% relative to the non-transgenic control oil and commercial Perilla oil, respectively. The low acid value suggests that the oil will be less susceptible to lipase action, and more economically viable and thus, may also improve the oil quality for industrial purposes. In addition, extracts obtained from transgenic plants could be a potential source of antimicrobial agents for the treatment of bacterial infections.

      PubDate: 2017-06-11T20:33:30Z
      DOI: 10.1016/j.plaphy.2017.06.006
       
  • Drought responsive microRNAs in two barley cultivars differing in their
           level of sensitivity to drought stress
    • Authors: Ehsan Mohseni Fard; Behnam Bakhshi; Reza Keshavarznia; Nava Nikpay; Maryam Shahbazi; Ghasem Hosseini Salekdeh
      Abstract: Publication date: Available online 7 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Ehsan Mohseni Fard, Behnam Bakhshi, Reza Keshavarznia, Nava Nikpay, Maryam Shahbazi, Ghasem Hosseini Salekdeh
      MicroRNAs (miRNAs) are known to be involved in the regulation of gene expression, including that of genes involved in the response to stress. Here, a comparison has been drawn between the miRNA profiles of a drought susceptible, 'Morocco 9–75′, and a drought tolerant, ‘Yousef’, barley cultivars. Leaf water content, shoot dry matter and chlorophyll content decreased in 'Morocco 9–75′ more considerably compared with ‘Yousef’ under drought stress. Furthermore, lower stomatal conductance and higher leaf temperature were observed in 'Morocco 9–75′ compared with ‘Yousef’. Based on the criteria set for differential abundance, 118 of conserved and novel miRNAs were identified as being responsive to soil water status. Although drought stress resulted in an altered abundance of more miRNAs in 'Morocco 9–75′ than in ‘Yousef’, drought stress was generally associated with an increased miRNA abundance in 'Yousef' and a decreased abundance in 'Morocco 9–75'. An in silico analysis identified 645 genes as putative targets for the drought-responsive miRNAs in 'Yousef' and 3735 in 'Morocco 9–75'. Gene ontology analysis showed that drought stress was associated with the altered abundance of miRNAs targeting growth, development, the juvenile to adult transition and hormone signaling. Some miRNAs which became more abundant in 'Yousef' are thought to target genes intimately involved in development and stress adaptation. In 'Morocco 9–75′, drought stress induced changes in the abundance of miRNAs associated with genes affecting growth, development, the juvenile to adult transition and ABA signaling. The data imply that miRNAs may affect the tolerance/sensitivity of barley to drought stress by modulating the expression of a wide set of genes and induction of some physiological changes.

      PubDate: 2017-06-11T20:33:30Z
      DOI: 10.1016/j.plaphy.2017.06.007
       
  • Overexpressing IbCBF3 increases low temperature and drought stress
           tolerance in transgenic sweetpotato
    • Authors: Rong Jin; Beg Hab Kim; Chang Yoon Ji; Ho Soo Kim; Hong Min Li; Dai Fu Ma; Sang-Soo Kwak
      Abstract: Publication date: Available online 3 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Rong Jin, Beg Hab Kim, Chang Yoon Ji, Ho Soo Kim, Hong Min Li, Dai Fu Ma, Sang-Soo Kwak
      Dehydration-responsive element-binding/C-repeat-binding factor (DREB/CBF) proteins regulate the transcription of genes involved in cold acclimation in several species. However, little is known about the physiological functions of CBF proteins in the low temperature-sensitive crop sweetpotato. We previously reported that the DREB1/CBF-like sweetpotato gene SwDREB1/IbCBF3 is involved in responses to diverse abiotic stresses. In this study, we confirmed that IbCBF3 is localized to the nucleus and binds to the C-repeat/dehydration-responsive elements (CRT/DRE) in the promoters of cold-regulated (COR) genes. We generated transgenic sweetpotato plants overexpressing IbCBF3 under the control of the CaMV 35S promoter (referred to as SC plants) and evaluated their responses to various abiotic stresses. IbCBF3 expression was dramatically induced by cold and drought but much less strongly induced by high salinity and ABA. We further characterized two SC lines (SC3 and SC6) with high levels of IbCBF3 transcript. The SC plants displayed enhanced tolerance to cold, drought, and oxidative stress on the whole-plant level. Under cold stress treatment (4 °C for 48 h), severe wilting and chilling injury were observed in the leaves of wild-type (WT) plants, whereas SC plants were not affected by cold stress. In addition, the COR genes were significantly upregulated in SC plants compared with the WT. The SC plants also showed significantly higher tolerance to drought stress than the WT, which was associated with higher photosynthesis efficiency and lower hydrogen peroxide levels. These results indicate that IbCBF3 is a functional transcription factor involved in the responses to various abiotic stresses in sweetpotato.

      PubDate: 2017-06-06T20:29:25Z
      DOI: 10.1016/j.plaphy.2017.06.002
       
  • Structural changes in cell wall pectins during strawberry fruit
           development
    • Authors: Candelas Paniagua; Nieves Santiago-Doménech; Andrew R. Kirby; A. Patrick Gunning; Victor J. Morris; Miguel A. Quesada; Antonio J. Matas; José A. Mercado
      Abstract: Publication date: Available online 2 June 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Candelas Paniagua, Nieves Santiago-Doménech, Andrew R. Kirby, A. Patrick Gunning, Victor J. Morris, Miguel A. Quesada, Antonio J. Matas, José A. Mercado
      Strawberry (Fragaria × anannasa Duch.) is one of the most important soft fruit. Rapid loss of firmness occurs during the ripening process, resulting in a short shelf life and high economic losses. To get insight into the role of pectin matrix in the softening process, cell walls from strawberry fruit at two developmental stages, unripe-green and ripe-red, were extracted and sequentially fractionated with different solvents to obtain fractions enriched in a specific component. The yield of cell wall material as well as the per fresh weight contents of the different fractions decreased in ripe fruit. The largest reduction was observed in the pectic fractions extracted with a chelating agent (trans-1,2- diaminocyclohexane-N,N,N’N’-tetraacetic acid, CDTA fraction) and those covalently bound to the wall (extracted with Na2CO3). Uronic acid content of these two fractions also decreased significantly during ripening, but the amount of soluble pectins extracted with phenol:acetic acid:water (PAW) and water increased in ripe fruit. Fourier transform infrared spectroscopy of the different fractions showed that the degree of esterification decreased in CDTA pectins but increased in soluble fractions at ripen stage. The chromatographic analysis of pectin fractions by gel filtration revealed that CDTA, water and, mainly PAW polyuronides were depolymerised in ripe fruit. By contrast, the size of Na2CO3 pectins was not modified. The nanostructural characteristics of CDTA and Na2CO3 pectins were analysed by atomic force microscopy (AFM). Isolated pectic chains present in the CDTA fractions were significantly longer and more branched in samples from green fruit than those from red fruit. No differences in contour length were observed in Na2CO3 strands between samples of both stages. However, the percentage of branched chains decreased from 19.7% in unripe samples to 3.4% in ripe fruit. The number of pectin aggregates was higher in green fruit samples of both fractions. These results show that the nanostructural complexity of pectins present in CDTA and Na2CO3 fractions diminishes during fruit development, and this correlates with the solubilisation of pectins and the softening of the fruit.

      PubDate: 2017-06-06T20:29:25Z
      DOI: 10.1016/j.plaphy.2017.06.001
       
 
 
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