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Journal Cover   Plant Physiology and Biochemistry
  [SJR: 1.041]   [H-I: 70]   [9 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0981-9428
   Published by Elsevier Homepage  [2812 journals]
  • Are ineffective defence reactions potential target for induced resistance
           during the compatible wheat-powdery mildew interaction'
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Ch. Tayeh, B. Randoux, B. Tisserant, G. Khong, Ph. Jacques, Ph. Reignault
      Powdery mildew caused by Blumeria graminis f.sp. tritici, an obligate aerial biotrophic fungus, would be one of the most damaging wheat (Triticum aestivum) diseases without the extensive use of conventional fungicides. In our study, the expression levels of some basal defence-related genes were investigated during a compatible interaction in order to evaluate wheat reactions to infection, along with the different stages of the infectious process in planta. As fungal conidia initiated their germination and developed appressorial germ tube (AGT), early defence reactions involved the expression of a lipoxygenase (LOX)- and an oxalate oxidase (OXO)-encoding genes, followed by activations of corresponding LOX (EC 1.13.11.12) and OXO (EC 1.2.3.4) activities, respectively. When penetration of AGT took place, up-regulation of chitinases (CHI) and PR1-encoding genes expression occurred along with an increase of CHI (EC 3.2.1.14) activity. Meanwhile, expression of a phenylalanine ammonia-lyase-encoding gene also took place. Up-regulation of a phospholipase C- and lipid transfer proteins-encoding genes expression occurred during the latest stages of infection. Neither the phi glutathione S-transferase (GST)-encoding gene expression nor the GST (EC 2.5.1.13) activity was modified upon wheat infection by powdery mildew. Whether these defence reactions during such a compatible interaction are markers of immunity or susceptibility, and whether they have the ability to contribute to protection upon modulation of their timing and their intensity by resistance inducers are discussed.


      PubDate: 2015-07-27T07:45:49Z
       
  • Effects of water deficit on radicle apex elongation and solute
           accumulation in Zea mays L
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): S. Velázquez-Márquez, V. Conde-Martínez, C. Trejo, A. Delgado-Alvarado, A. Carballo, R. Suárez, J.O. Mascorro, A.R. Trujillo
      In this study, we examined the effects of water deficit on the elongation of radicles of maize seedlings and on the accumulation of solutes in the radicle apices of two maize varieties: VS-22 (tolerant) and AMCCG-2 (susceptible). Sections of radicle corresponding to the first 2 mm of the primary roots were marked with black ink, and the seedlings were allowed to grow for 24, 48, and 72 h in polyvinyl chloride (PVC) tubes filled with vermiculite at three different water potentials (Ψw, −0.03, −1.0, and −1.5 MPa). The radicle elongation, sugar accumulation, and proline accumulation were determined after each of the growth periods specified above. The Ψw of the substrate affected the dynamics of primary root elongation in both varieties. In particular, the lowest Ψw (−1.5 MPa) inhibited root development by 72% and 90% for the VS-22 and AMCCG-2 varieties, respectively. The osmotic potential (Ψo) was reduced substantially in both varieties to maintain root turgor; however, VS-22 had a higher root turgor (0.67 MPa) than AMCCG-2 (0.2 MPa). These results suggest that both varieties possess a capacity for osmotic adjustment. Sugar began to accumulate within the first 24 h of radicle apex growth. The sugar concentration was higher in VS-22 root apices compared to AMCCG-2, and the amount of sugar accumulation increased with a decrease in Ψw. Significant amounts of trehalose accumulated in VS-22 and AMCCG-2 (29.8 μmol/g fresh weight [FW] and 5.24 μmol/g FW, respectively). Starch accumulation in the root apices of these two maize varieties also differed significantly, with a lower level in VS-22. In both varieties, the proline concentration also increased as a consequence of the water deficit. At 72 h, the proline concentration in VS-22 (16.2 μmol/g FW) was almost 3 times greater than that in AMCCG-2 (5.19 μmol/g FW). Trehalose also showed a 3-fold increase in the tolerant variety. Accumulation of these solutes in the root growth zone may indicate an osmotic adjustment (OA) to maintain turgor pressure.


      PubDate: 2015-07-27T07:45:49Z
       
  • Effects of phosphorus application on photosynthetic carbon and nitrogen
           metabolism, water use efficiency and growth of dwarf bamboo (Fargesia
           rufa) subjected to water deficit
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Chenggang Liu, Yanjie Wang, Kaiwen Pan, Yanqiang Jin, Wei Li, Lin Zhang
      Dwarf bamboo (Fargesia rufa Yi), one of the staple foods for the endangered giant pandas, is highly susceptible to water deficit due to its shallow roots. In the face of climate change, maintenance and improvement in its productivity is very necessary for the management of the giant pandas' habitats. However, the regulatory mechanisms underlying plant responses to water deficit are poorly known. To investigate the effects of P application on photosynthetic C and N metabolism, water use efficiency (WUE) and growth of dwarf bamboo under water deficit, a completely randomized design with two factors of two watering (well-watered and water-stressed) and two P regimes (with and without P fertilization) was arranged. P application hardly changed growth, net CO2 assimilation rate (P n) and WUE in well-watered plants but significantly increased relative growth rate (RGR) and P n in water-stressed plants. The effect of P application on RGR under water stress was mostly associated with physiological adjustments rather than with differences in biomass allocation. P application maintained the balance of C metabolism in well-watered plants, but altered the proportion of nitrogenous compounds in N metabolism. By contrast, P application remarkably increased sucrose-metabolizing enzymes activities with an obvious decrease in sucrose content in water-stressed plants, suggesting an accelerated sucrose metabolism. Activation of nitrogen-metabolizing enzymes in water-stressed plants was attenuated after P application, thus slowing nitrate reduction and ammonium assimilation. P application hardly enlarged the phenotypic plasticity of dwarf bamboo in response to water in the short term. Generally, these examined traits of dwarf bamboo displayed weak or negligible responses to water-P interaction. In conclusion, P application could accelerate P n and sucrose metabolism and slow N metabolism in water-stressed dwarf bamboo, and as a result improved RGR and alleviated damage from soil water deficit.


      PubDate: 2015-07-27T07:45:49Z
       
  • Volatile squalene from a nonseed plant Selaginella moellendorffii:
           Emission and biosynthesis
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Yifan Jiang, Hao Chen, Xinlu Chen, Tobias G. Köllner, Qidong Jia, Troy W. Wymore, Fei Wang, Feng Chen
      The triterpene squalene is a key metabolic intermediate for sterols, hopanoids and various other triterpenoids. The biosynthesis of squalene is catalyzed by squalene synthase (SQS), which converts two molecules of farnesyl diphosphate to squalene. In this study, a lycophyte Selaginella moellendorffii was found to emit squalene as a volatile compound under a number of conditions that mimic biotic stresses. Searching the genome sequence of S. moellendorffii led to the identification of a putative squalene synthase gene. It was designated as SmSQS. SmSQS is homologous to known squalene synthases from other plants and animals at both the amino acid level and structural level. Recombinant SmSQS expressed in Escherichia coli catalyzed the formation of squalene using farnesyl diphosphate as substrate. The expression of SmSQS was significantly induced by the same set of stress factors that induced the emission of volatile squalene from S. moellendorffii plants. Taken together, these results support that SmSQS is responsible for the biosynthesis of volatile squalene and volatile squalene may have a role in the defense of S. moellendorffii plants against biotic stresses.


      PubDate: 2015-07-27T07:45:49Z
       
  • Genome-wide identification of abiotic stress-regulated and novel microRNAs
           in mulberry leaf
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Ping Wu, Shaohua Han, Weiguo Zhao, Tao Chen, Jiachun Zhou, Long Li
      As the most important food plant for sericultural industry, mulberry trees have to suffer from a wide range of abiotic and biotic stresses, such as drought and high salinity. MicroRNAs (miRNAs) have been proved to play important roles in abiotic stresses regulation in many plants. However, there are seldom reports on the miRNAs expression profiles upon abiotic challenges in mulberry. In this study, three small RNA libraries from mulberry leaf tissue with or without drought or salt treatment were constructed and deep sequenced. Total of 48 conserved miRNAs (including miRNA*) and 162 novel miRNAs were identified (processing precision value>0.1). A total of 270 and 1963 target genes were predicted for conserved miRNAs and novel miRNAs, respectively. 13 differentially expressed miRNAs were detected under drought or salt stresses by deep sequencing and qRT-PCR. 5′ RLM-RACE validated Morus 013341 to be the target gene of miR-395a. Our results provided initial clue to further study molecular mechanism on abiotic stresses regulation in mulberry.


      PubDate: 2015-07-18T23:41:08Z
       
  • Evaluation of Aegilops tauschii and Aegilops speltoides for acquired
           thermotolerance: Implications in wheat breeding programmes
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Suboot Hairat, Paramjit Khurana
      Severe and frequent heat waves are predicted in the near future having dramatic and far-reaching ecological and social impact. The aim of this study was to examine acquired thermotolerance of two Aegilops species: Aegilops tauschii and Aegilops speltoides and study their potential adaptive mechanisms. The effect of two episodes of high heat stress (45 °C/12 h) with a day of recovery period was investigated on their physiology. As compared to A. speltoides, A. tauschii suffered less inhibition of photosystem II efficiency and net photosynthetic rate (Pn). Although A. tauschii showed nearly complete recovery of PSII, the adverse effect was more pronounced in A. speltoides. Measurement of the minimum fluorescence (Fo) versus temperature curves revealed a higher inflection temperature of Fo for A. tauschii than A. speltoides, reflecting greater thermo stability of the photosynthetic apparatus. Absorbed light energy distribution revealed that A. speltoides showed increased steady state fluorescence and a lower absorbed light allocated to photosynthetic chemistry (ɸPSII) relative to A. tauschii. However, A. tauschii showed higher ability to scavenge free radicals as compared to A. speltoides. This was further validated by higher expression of ascorbate peroxidase gene. These results suggest that A. tauschii showed faster recovery and a better thermostability of its photosynthetic apparatus under severe stress conditions along with a better regulation of energy channeling of PSII complexes to minimize oxidative damage and thus retains greater capability of carbon assimilation. These factors aid in imparting a greater heat tolerance to A. tauschii as compared to A. speltoides and thus make it a better candidate for alien species introgression in wheat breeding programs for thermotolerance in wheat.


      PubDate: 2015-07-18T23:41:08Z
       
  • Editorial Board
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94




      PubDate: 2015-07-18T23:41:08Z
       
  • Ectopic overexpression of the aldehyde dehydrogenase ALDH21 from
           Syntrichia caninervis in tobacco confers salt and drought stress tolerance
           
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Honglan Yang, Daoyuan Zhang, Haiyan Li, Lingfeng Dong, Haiyan Lan
      Aldehyde dehydrogenases are important enzymes that play vital roles in mitigating oxidative/electrophilic stress when plants are exposed to environmental stress. An aldehyde dehydrogenase gene from Syntrichia caninervis, ScALDH21, was introduced into tobacco using Agrobacterium-mediated transformation to generate ScALDH21-overexpressing tobacco plants to investigate its effect on drought and salt resistance. Detached leaves from ScALDH21-overexpressing tobacco plants showed less water loss than those from nontransgenic plants. When subjected to drought and salt stress, transgenic plants displayed higher germination ratios, higher root lengths, greater fresh weight, higher proline accumulation, lower malondialdehyde (MDA) contents and stronger photosynthetic capacities, as well as higher activities of antioxidant enzymes, i.e., superoxide dismutase, catalase and peroxidase, compared with control plants. Therefore, ScALDH21 overexpression in transgenic tobacco plants can enhance drought and salt tolerance and can be used as a candidate gene for the molecular breeding of salt- and drought-tolerant plants.


      PubDate: 2015-07-18T23:41:08Z
       
  • Genotypic variation in growth and metabolic responses of perennial
           ryegrass exposed to short-term waterlogging and submergence stress
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Mingxi Liu, Yiwei Jiang
      Physiological mechanisms of waterlogging (WL) and submergence (SM) tolerance are not well understood in perennial grasses used for turf and forage. The objective of this study was to characterize growth, antioxidant activity and lipid peroxidation of perennial ryegrass (Lolium perenne) exposed to short-term WL and SM. ‘Silver Dollar’ (turf-type cultivar), ‘PI418714’ (wild accession), ‘Kangaroo Valley’ (forage-type cultivar) and ‘PI231569’ (unknown status) varying in growth habits and leaf texture were subjected to 7 d of WL and SM in a growth chamber. Plant height was unaffected by WL but was significantly reduced by SM for all grasses except PI418714. The SM treatment caused greater reductions in leaf chlorophyll and total carotenoid concentrations. Substantial declines in water-soluble carbohydrate concentrations were found in the shoots and roots under SM, particularly in Kangaroo Valley and PI231569, two relatively fast-growing genotypes. Significant increases in malondialdehyde concentrations were noted in the shoots and roots of all genotypes exposed to WL and SM, but to a greater extent in Kangaroo Valley and PI231569 under SM. Shoot activities of catalase (CAT) and peroxidase (POD) increased under SM, more pronounced in Silver Dollar and PI418714, two relatively slow-growing genotypes. Waterlogging or SM stresses decreased root activities of superoxide dismutase, CAT, POD and ascorbate peroxidase, especially for Kangaroo Valley and PI231569. The results indicated that maintenance of antioxidant activity and carbohydrate and minimization of lipid peroxidation could contribute to better waterlogging or submergence tolerance of perennial ryegrasses.


      PubDate: 2015-07-18T23:41:08Z
       
  • The over-expression of a chrysanthemum WRKY transcription factor enhances
           aphid resistance
    • Abstract: Publication date: Available online 6 July 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Peiling Li , Aiping Song , Chunyan Gao , Jiafu Jiang , Sumei Chen , Weimin Fang , Fei Zhang , Fadi Chen
      Members of the large WRKY transcription factor family are responsible for the regulation of plant growth, development and the stress response. Here, five WRKY members were isolated from chrysanthemum. They each contained a single WRKY domain and a C2H2 zinc finger motif, so were classified into group II. Transient expression experiments demonstrated that all five were expressed in the nucleus, although CmWRKY42 was also expressed in the cytoplasm. When expressed heterologously in yeast, the products of CmWRKY22 and CmWRKY48 exhibited transactivation activity, while those of CmWRKY21, CmWRKY40 and CmWRKY42 did not. The transcription of the five CmWRKY genes was profiled when the plants were challenged with a variety of abiotic and biotic stress agents, as well as being treated with various phytohormones. CmWRKY21 proved to be markedly induced by salinity stress, and suppressed by high temperature exposure; CmWRKY22 was induced by high temperature exposure; CmWRKY40 was highly induced by salinity stress, and treatment with either abscisic acid (ABA) or methyl jasmonate (MeJA); CmWRKY42 was up-regulated by salinity stress, low temperature, ABA and MeJA treatment and aphid infestation; CmWRKY48 was induced by drought stress, ABA and MeJA treatment and aphid infestation. The function of CmWRKY48 was further investigated by over-expressing it transgenically. The constitutive expression of this transcription factor inhibited the aphids' population growth capacity, suggesting that it may represent an important component of the plant's defense machinery against aphids.


      PubDate: 2015-07-09T14:20:18Z
       
  • Salinity affects production and salt tolerance of dimorphic seeds of
           Suaeda salsa
    • Abstract: Publication date: Available online 6 July 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Fengxia Wang , Yange Xu , Shuai Wang , Weiwei Shi , Ranran Liu , Gu Feng , Jie Song
      The effect of salinity on brown seeds/black seeds ratio, seed weight, endogenous hormone concentrations, and germination of brown and black seeds in the euhalophyte Suaeda salsa was investigated. The brown seeds/black seeds ratio, seed weight of brown and black seeds and the content of protein increased at a concentration of 500 mM NaCl compared to low salt conditions (1 mM NaCl). The germination percentage and germination index of brown seeds from plants cultured in 500 mM NaCl were higher than those cultured in 1 mM NaCl, but it was not true for black seeds. The concentrations of IAA (indole-3-acetic acid), ZR (free zeatin riboside) and ABA (abscisic acid) in brown seeds were much greater than those in black seeds, but there were no differences in the level of GAs (gibberellic acid including GA1 and GA3) regardless of the degree of salinity. Salinity during plant culture increased the concentration of GAs, but salinity had no effect on the concentrations of the other three endogenous hormones in brown seeds. Salinity had no effect on the concentration of IAA but increased the concentrations of the other three endogenous hormones in black seeds. Accumulation of endogenous hormones at different concentrations of NaCl during plant growth may be related to seed development and to salt tolerance of brown and black S. salsa seeds. These characteristics may help the species to ensure seedling establishment and population succession in variable saline environments.


      PubDate: 2015-07-09T14:20:18Z
       
  • Arabidopsis thaliana polyamine content is modified by the interaction with
           different Trichoderma species
    • Abstract: Publication date: Available online 6 July 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Fatima Berenice Salazar-Badillo , Diana Sánchez-Rangel , Alicia Becerra-Flora , Miguel López-Gómez , Fernanda Nieto-Jacobo , Artemio Mendoza-Mendoza , Juan Francisco Jiménez-Bremont
      Plants are associated with a wide range of microorganisms throughout their life cycle, and some interactions result on plant benefits. Trichoderma species are plant beneficial fungi that enhance plant growth and development, contribute to plant nutrition and induce defense responses. Nevertheless, the molecules involved in these beneficial effects still need to be identify. Polyamines are ubiquitous molecules implicated in plant growth and development, and in the establishment of plant microbe interactions. In this study, we assessed the polyamine profile in Arabidopsis plants during the interaction with Trichoderma virens and Trichoderma atroviride, using a system that allows direct plant-fungal contact or avoids their physical interaction (split system). The plantlets that grew in the split system exhibited higher biomass than the ones in direct contact with Trichoderma species. After 3 days of interaction, a significant decrease in Arabidopsis polyamine levels was observed in both systems (direct contact and split). After 5 days of interaction polyamine levels were increased. The highest levels were observed with Trichoderma atroviride (split system), and with Trichoderma virens (direct contact). The expression levels of Arabidopsis ADC1 and ADC2 genes during the interaction with the fungi were also assessed. We observed a time dependent regulation of ADC1 and ADC2 genes, which correlates with polyamine levels. Our data show an evident change in polyamine profile during Arabidopsis – Trichoderma interaction, accompanied by evident alterations in plant root architecture. Polyamines could be involved in the changes undergone by plant during the interaction with this beneficial fungus.


      PubDate: 2015-07-09T14:20:18Z
       
  • Comparative transcriptome analysis reveals defense-related genes and
           pathways against downy mildew in Vitis amurensis grapevine
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Xinlong Li , Jiao Wu , Ling Yin , Yali Zhang , Junjie Qu , Jiang Lu
      Downy mildew (DM), caused by oomycete Plasmopara viticola (Pv), can lead to severe damage to Vitis vinifera grapevines. Vitis amurensis has generally been regarded as a DM resistant species. However, when V. amurensis ‘Shuanghong’ were inoculated with Pv strains ‘ZJ-1-1’ and ‘JL-7-2’, the former led to obvious DM symptoms (compatible), while the latter did not develop any DM symptoms but exhibited necrosis (incompatible). In order to underlie molecular mechanism in DM resistance, mRNA-seq based expression profiling of ‘Shuanghong’ was compared at 12, 24, 48 and 72 h post inoculation (hpi) with these two strains. Specific genes and their corresponding pathways responsible for incompatible interaction were extracted by comparing with compatible interaction. In the incompatible interaction, 37 resistance (R) genes were more expressed at the early stage of infection (12 hpi). Similarly, genes involved in defense signaling, including MAPK. ROS/NO, SA, JA, ET and ABA pathways, and genes associated with defense-related metabolites synthesis, such as pathogenesis-related genes and phenylpropanoids/stilbenoids/flavonoids biosynthesizing genes, were also activated mainly during the early stages of infection. On the other hand, Ca2+ signaling and primary metabolism, such as photosynthesis and fatty acid synthesis, were more repressed after ‘JL-7-2’ challenge. Further quantification of some key defense-related factors, including phytohormones, phytoalexins and ROS, generally showed much more accumulation during the incompatible interaction, indicating their important roles in DM defense. In addition, a total of 43 and 52 RxLR effectors were detected during ‘JL-7-2’ and ‘ZJ-1-1’ infection processes, respectively.


      PubDate: 2015-07-05T14:16:59Z
       
  • Lysozyme- and chitinase activity in latex bearing plants of genus
           Euphorbia - a contribution to plant defense mechanism
    • Abstract: Publication date: Available online 3 July 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Sonja Sytwala , Florian Günther , Matthias F. Melzig
      Occurrence of latices in plants is widespread, there are 40 families of plants characterized to establish lactiferous structures. Latices exhibit a constitutive part of plant defense due to the stickiness. The appearance of proteins incorporated in latices is well characterized, and hydrolytic active proteins are considerable. A lot of plants constitute so-called pathogenesis-related (PR) proteins, to overcome stressful conditions. In our investigation we are focused on latex bearing plants of Euphorbiaceae Juss., and investigated the appearance of chitinase- and lysozyme activity in particular. The present outcomes represent a comprehensive study, relating to the occurrence of lysozyme and chitinase activity of genus Euphorbia at the first time. 110 different species of genus Euphorbia L. were tested, and the appearance of chitinase and lysozyme were determined in different quantities. The appearance itself, and the physicochemical properties of latices indicate an efficient interaction for plant defense against pathogen attack.


      PubDate: 2015-07-05T14:16:59Z
       
  • Effect of wood ash application on the morphological, physiological and
           biochemical parameters of Brassica napus L.
    • Abstract: Publication date: Available online 2 July 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Farhat Nabeela , Waheed Murad , Imran Khan , Ishaq Ahmad Mian , Hazir Rehman , Muhammad Adnan , Azizullah Azizullah
      The present study was conducted to determine the effect of wood ash application on different parameters of Brassica napus L. including seed germination, seedling growth, fresh and dry biomass, water content in seedlings, photosynthetic pigments, soluble sugars, total protein and cell viability. In addition, the effect of wood ash on soil microflora and accumulation of trace elements in seedlings was determined. The seeds of B. napus were grown at different doses of wood ash (0, 1, 10, 25, 50 and 100 g (wood ash)/kg (soil)) and the effect on various parameters was determined. Wood ash significantly inhibited seed germination at doses above 25 g/kg and there was no germination at 100 g/kg of wood ash. At lower concentrations of wood ash, most of the growth parameters of seedlings were stimulated, but at higher concentrations of wood ash most of the studied parameters were adversely affected. Wood ash was found to be very detrimental to B. napus when applied above 25 g/kg. Wood ash application resulted in an increased bioaccumulation of trace elements in seedlings of B. napus. Almost all trace elements were significantly higher in seedlings grown in wood ash above 10 g/kg as compared to the control. An increase in total microbial count was observed with wood ash treatment which was statistically significant at 1 and 10 g/kg of wood ash. It is concluded that at very high concentration, wood ash can be detrimental to plants; however, its application at lower application rate can be recommended.


      PubDate: 2015-07-05T14:16:59Z
       
  • Analysis of Arabidopsis thaliana atfer4-1, atfh and atfer4-1/atfh mutants
           uncovers frataxin and ferritin contributions to leaf ionome homeostasis
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Irene Murgia , Gianpiero Vigani
      Ferritins are iron-storage proteins involved in the environmental and developmental control of the free iron pool within cells. Plant ferritins are targeted to mitochondria as well as to chloroplasts. AtFer4 is the Arabidopsis thaliana ferritin isoform that can be also targeted to mitochondria. Frataxin is a mitochondrial protein whose role is essential for plants; lack of AtFH frataxin causes early embryo-lethality in Arabidopsis. Because of that, the Arabidopsis atfh KO mutant is propagated in heterozygosis. For exploring the functional interaction between frataxin and ferritin, Arabidopsis double mutant atfer4-1/atfh was isolated and its physiological parameters were measured, as well as its ionome profile, together with those of both atfer4 and atfh single mutants, in different conditions of Fe supply. Impairment of both ferritin and frataxin did not lead to any effect on mitochondrial respiration. However, ionomics revealed that the content of macro- and microelements, occurring when the nutritional Fe supply changes, were altered in the mutants analysed. These results suggest that both ferritin and frataxin can contribute to the composition of the leaf ionome and also confirm ionomics as an excellent tool for detecting alterations in the plant's physiology.


      PubDate: 2015-07-01T14:00:39Z
       
  • In silico analysis and expression profiling of miRNAs targeting genes of
           steviol glycosides biosynthetic pathway and their relationship with
           steviol glycosides content in different tissues of Stevia rebaudiana
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Monica Saifi , Nazima Nasrullah , Malik Mobeen Ahmad , Athar Ali , Jawaid A. Khan , M.Z. Abdin
      miRNAs are emerging as potential regulators of the gene expression. Their proven promising role in regulating biosynthetic pathways related gene networks may hold the key to understand the genetic regulation of these pathways which may assist in selection and manipulation to get high performing plant genotypes with better secondary metabolites yields and increased biomass. miRNAs associated with genes of steviol glycosides biosynthetic pathway, however, have not been identified so far. In this study miRNAs targeting genes of steviol glycosides biosynthetic pathway were identified for the first time whose precursors were potentially generated from ESTs and nucleotide sequences of Stevia rebaudiana. Thereafter, stem-loop coupled real time PCR based expressions of these miRNAs in different tissues of Stevia rebaudiana were investigated and their relationship pattern was analysed with the expression levels of their target mRNAs as well as steviol glycoside contents. All the miRNAs investigated showed differential expressions in all the three tissues studied, viz. leaves, flowers and stems. Out of the eleven miRNAs validated, the expression levels of nine miRNAs (miR319a, miR319b, miR319c, miR319d, miR319e, miR319f, miR319h, miRstv_7, miRstv_9) were found to be inversely related, while expression levels of the two, i.e. miR319g and miRstv_11 on the contrary, showed direct relation with the expression levels of their target mRNAs and steviol glycoside contents in the leaves, flowers and stems. This study provides a platform for better understanding of the steviol glycosides biosynthetic pathway and these miRNAs can further be employed to manipulate the biosynthesis of these metabolites to enhance their contents and yield in S. rebaudiana.


      PubDate: 2015-07-01T14:00:39Z
       
  • Thyme essential oil as a defense inducer of tomato against gray mold and
           Fusarium wilt
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Maissa Ben-Jabeur , Emna Ghabri , Machraoui Myriam , Walid Hamada
      The potential of thyme essential oil in controlling gray mold and Fusarium wilt and inducing systemic acquired resistance in tomato seedlings and tomato grown in hydroponic system was evaluated. Thyme oil highly reduced 64% of Botrytis cinerea colonization on pretreated detached leaves compared to untreated control. Also, it played a significant decrease in Fusarium wilt severity especially at7 days post treatment when it was reduced to 30.76%. To explore the plant pathways triggered in response to thyme oil, phenolic compounds accumulation and peroxidase activity was investigated. Plant response was observed either after foliar spray or root feeding in hydroponics which was mostly attributed to peroxidases accumulation rather than phenolic compounds accumulation, and thyme oil seems to be more effective when applied to the roots.
      Graphical abstract image

      PubDate: 2015-07-01T14:00:39Z
       
  • Heterologous expression of ACC deaminase from Trichoderma asperellum
           improves the growth performance of Arabidopsis thaliana under normal and
           salt stress conditions
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Fuli Zhang , Ju Zhang , Long Chen , Xiaoying Shi , Zhihua Lui , Chengwei Li
      Transgenic Arabidopsis thaliana plants expressing the 1-aminocyclopropane-1-carboxylate deaminase gene (ACCD) of Trichoderma asperellum ACCC30536 (TaACCD) were created and their growth performance was assessed under normal and salt stress conditions. In order to characterize their growth, root length, root number, fresh weight (FW), relative water content (RWC), seed production, and seed number were measured. Under normal growing condition, all growth parameters except for dry weight (DW) of the transgenic plants increased significantly compared to WT plants. Furthermore, the transgenic line also exhibited higher tolerance and faster growth than WT plants in the presence of 150 mM NaCl. The increased salt stress tolerance of the transgenic plants is attributed to a greater RWC, root weight, root length, root number and FW under salt stress, and to reduced reactive oxygen species (ROS) level, cell death and electrolyte leakage compared to WT plants. The reduction in ROS levels could be explained by increased activity of several antioxidant enzymes, including peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). Thus, we propose that heterologous expression of TaACCD could be used to improve salt stress tolerance in plants.


      PubDate: 2015-07-01T14:00:39Z
       
  • Shoot ionome to predict the synergism and antagonism between nutrients as
           affected by substrate and physiological status
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Youry Pii , Stefano Cesco , Tanja Mimmo
      The elemental composition of a tissue or organism is defined as ionome. However, the combined effects on the shoot ionome determined by the taxonomic character, the nutrient status and different substrates have not been investigated. This study tests the hypothesis that phylogenetic variation of monocots and dicots grown in iron deficiency can be distinguished by the shoot ionome. We analyzed 18 elements in barley, cucumber and tomato and in two substrates (hydroponic vs soil) with different nutritional regimes. Multivariate analysis evidenced a clear separation between the species. In hydroponic conditions the main drivers separating the species are non essential-nutrients as Ti, Al, Na and Li, which were positively correlated with macro- (P, K) and micronutrients (Fe, Zn, Mo, B). The separation between species is confirmed when plants are grown on soil, but the distribution is determined especially by macronutrients (S, P, K, Ca, Mg) and micronutrients (B). A number of macro (Mg, Ca, S, P, K) and micronutrients (Fe, Mn, Zn, Cu, Mo, B) contribute to plant growth and several other important physiological and metabolic plant activities. The results reported here confirmed that the synergism and antagonism between them and other non-essential elements (Ti, Al, Si, Na) define the plant taxonomic character. The ionome profile might thus be exploited as a tool for the diagnosis of plants physiological/nutritional status but also in defining biofortification strategies to optimize both mineral enrichment of staple food crops and the nutrient input as fertilizers.


      PubDate: 2015-07-01T14:00:39Z
       
  • Mutagenesis during plant responses to UVB radiation
    • Abstract: Publication date: August 2015
      Source:Plant Physiology and Biochemistry, Volume 93
      Author(s): M. Holá , R. Vágnerová , K.J. Angelis
      We tested an idea that induced mutagenesis due to unrepaired DNA lesions, here the UV photoproducts, underlies the impact of UVB irradiation on plant phenotype. For this purpose we used protonemal culture of the moss Physcomitrella patens with 50% of apical cells, which mimics actively growing tissue, the most vulnerable stage for the induction of mutations. We measured the UVB mutation rate of various moss lines with defects in DNA repair (pplig4, ppku70, pprad50, ppmre11), and in selected clones resistant to 2-Fluoroadenine, which were mutated in the adenosine phosphotrasferase gene (APT), we analysed induced mutations by sequencing. In parallel we followed DNA break repair and removal of cyclobutane pyrimidine dimers with a half-life τ = 4 h 14 min determined by comet assay combined with UV dimer specific T4 endonuclease V. We show that UVB induces massive, sequence specific, error-prone bypass repair that is responsible for a high mutation rate owing to relatively slow, though error-free, removal of photoproducts by nucleotide excision repair (NER).


      PubDate: 2015-07-01T14:00:39Z
       
  • Editorial Board
    • Abstract: Publication date: August 2015
      Source:Plant Physiology and Biochemistry, Volume 93




      PubDate: 2015-07-01T14:00:39Z
       
  • There is nothing new under the sun
    • Abstract: Publication date: August 2015
      Source:Plant Physiology and Biochemistry, Volume 93
      Author(s): Marcel A.K. Jansen , Alenka Gaberščik , Marie-Theres Hauser



      PubDate: 2015-07-01T14:00:39Z
       
  • On the history of phyto-photo UV science (not to be left in skoto toto and
           silence)
    • Abstract: Publication date: August 2015
      Source:Plant Physiology and Biochemistry, Volume 93
      Author(s): Lars Olof Björn
      This review of the history of ultraviolet photobiology focuses on the effects of UV-B (280–315 nm) radiation on terrestrial plants. It describes the early history of ultraviolet photobiology, the discovery of DNA as a major ultraviolet target and the discovery of photoreactivation and photolyases, and the later identification of Photosystem II as another important target for damage to plants by UV-B radiation. Some experimental techniques are briefly outlined. The insight that the ozone layer was thinning spurred the interest in physiological and ecological effects of UV-B radiation and resulted in an exponential increase over time in the number of publications and citations until 1998, at which time it was realized by the research community that the Montreal Protocol regulating the pollution of the atmosphere with ozone depleting substances was effective. From then on, the publication and citation rate has continued to rise exponentially, but with an abrupt change to lower exponents. We have now entered a phase when more emphasis is put on the “positive” effects of UV-B radiation, and with more emphasis on regulation than on damage and inhibition.
      Graphical abstract image

      PubDate: 2015-07-01T14:00:39Z
       
  • Ultraviolet-B radiation stimulates downward leaf curling in Arabidopsis
           thaliana
    • Abstract: Publication date: August 2015
      Source:Plant Physiology and Biochemistry, Volume 93
      Author(s): Ana Carolina Fierro , Olivier Leroux , Barbara De Coninck , Bruno P.A. Cammue , Kathleen Marchal , Els Prinsen , Dominique Van Der Straeten , Filip Vandenbussche
      Plants are very well adapted to growth in ultraviolet-B (UV-B) containing light. In Arabidopsis thaliana, many of these adaptations are mediated by the UV-B receptor UV RESISTANCE LOCUS 8 (UVR8). Using small amounts of supplementary UV-B light, we observed changes in the shape of rosette leaf blades. Wild type plants show more pronounced epinasty of the blade edges, while this is not the case in uvr8 mutant plants. The UVR8 effect thus mimics the effect of phytochrome (phy) B in red light. In addition, a meta-analysis of transcriptome data indicates that the UVR8 and phyB signaling pathways have over 70% of gene regulation in common. Moreover, in low levels of supplementary UV-B light, mutant analysis revealed that phyB signaling is necessary for epinasty of the blade edges. Analysis of auxin levels and the auxin signal reporter DR5::GUS suggest that the epinasty relies on altered auxin distribution, keeping auxin at the leaf blade edges in the presence of UV-B. Together, our results suggest a co-action of phyB and UVR8 signaling, with auxin as a downstream factor.


      PubDate: 2015-07-01T14:00:39Z
       
  • Insights into B-type RR members as signaling partners acting downstream of
           HPt partners of HK1 in the osmotic stress response in Populus
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Lucie Bertheau , Inès Djeghdir , Emilien Foureau , Françoise Chefdor , Gaëlle Glevarec , Audrey Oudin , Christiane Depierreux , Domenico Morabito , Franck Brignolas , Vincent Courdavault , François Héricourt , Daniel Auguin , Sabine Carpin
      The B-type response regulators (B-type RRs), final elements of a signaling pathway called “histidine/aspartate phosphorelay system” in plants, are devoted to the regulation of response genes through a transcription factor activity. Signal transduction consists in the transfer of a phosphoryl group from a transmembrane histidine kinase (HK) which recognizes a given stimulus to nuclear RRs via cytosolic shuttle phosphotransfer proteins (HPts). In Arabidopsis, the receptors HK are to date the major characterized candidates to be responsible for initiation of osmotic stress responses. However, little information is available concerning the signaling partners acting downstream of HKs. In Populus, three HPts and five B-type RRs were previously identified as interacting partners of HK1, the Arabidopsis AHK1 homolog. Here, we report the isolation of RR18, a member of the B-type RR family, which shares high sequence similarities with ARR18 characterized to act in the osmosensing signaling pathway in Arabidopsis, from poplar cuttings subjected to osmotic stress conditions. By using yeast and in planta interaction assays, RR18 was further identified as acting downstream of HK1 and its three preferential HPt partners. Besides, our results are in favor of a possible involvement of both RR18 and RR13, the main expressed poplar B-type RR, in the osmotic signaling pathway. Nonetheless, different behaviors of these two B-type RRs in this pathway need to be noted, with one RR, RR13, acting in an early phase, mainly in roots of poplar cuttings, and the other one, RR18, acting in a late phase, mainly in leaves to supply an adequate response.


      PubDate: 2015-07-01T14:00:39Z
       
  • Regulation of FA and TAG biosynthesis pathway genes in endosperms and
           embryos of high and low oil content genotypes of Jatropha curcas L
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Archit Sood , Rajinder Singh Chauhan
      The rising demand for biofuels has raised concerns about selecting alternate and promising renewable energy crops which do not compete with food supply. Jatropha (Jatropha curcas L.), a non-edible energy crop of the family euphorbiaceae, has the potential of providing biodiesel feedstock due to the presence of high proportion of unsaturated fatty acids (75%) in seed oil which is mainly accumulated in endosperm and embryo. The molecular basis of seed oil biosynthesis machinery has been studied in J. curcas, however, what genetic differences contribute to differential oil biosynthesis and accumulation in genotypes varying for oil content is poorly understood. We investigated expression profile of 18 FA and TAG biosynthetic pathway genes in different developmental stages of embryo and endosperm from high (42%) and low (30%) oil content genotypes grown at two geographical locations. Most of the genes showed relatively higher expression in endosperms of high oil content genotype, whereas no significant difference was observed in endosperms versus embryos of low oil content genotype. The promoter regions of key genes from FA and TAG biosynthetic pathways as well as other genes implicated in oil accumulation were analyzed for regulatory elements and transcription factors specific to oil or lipid accumulation in plants such as Dof, CBF (LEC1), SORLIP, GATA and Skn-1_motif etc. Identification of key genes from oil biosynthesis and regulatory elements specific to oil deposition will be useful not only in dissecting the molecular basis of high oil content but also improving seed oil content through transgenic or molecular breeding approaches.


      PubDate: 2015-07-01T14:00:39Z
       
  • Pyrabactin regulates root hydraulic properties in maize seedlings by
           affecting PIP aquaporins in a phosphorylation-dependent manner
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Wenqiang Fan , Jia Li , Jia Jia , Fei Wang , Cuiling Cao , Jingjiang Hu , Zixin Mu
      Pyrabactin, an agonist of abscisic acid (ABA), has led to the isolation and characterization of pyrabactin resistance 1/pyrabactin resistance 1-like (PYR1/PYLs) ABA receptors in Arabidopsis, which has well explained ABA-mediated stomatal movement and stress-related gene expression. In addition to inducing stomatal closure and inhibiting transpiration, ABA can also enhance root hydraulic conductivity (Lp r), thus maintaining water balance under water deficiency-related stress, but its molecular mechanism remains unclear. In the present study, the root hydraulic properties of maize seedlings in response to pyrabactin were compared to those caused by ABA. Similar to ABA, lower concentration of pyrabactin induced a remarkable increase in Lp r as well as in the gene expression of the plasma membrane intrinsic protein (ZmPIP) aquaporin and in the ZmPIP2; 1/2; 2 protein abundance. The pyrabactin-induced enhancement of Lp r was abolished by H2O2 application, indicating that pyrabactin regulates Lp r by modulating ZmPIP at transcriptional, translational and post-translational (activity) level. Pyrabactin-mediated water transport and ZmPIP gene expression were phosphorylation-dependent, suggesting that ABA-PYR1-(PP2C)-protein kinase-AQP signaling pathway may be involved in this process. As we know this is the first established ABA signaling transduction pathway that mediated water transport in roots. This observation further addressed the importance of PYR1/PYLs ABA receptor in regulating plant water use efficiency from the under ground level. Except inhibiting transpiration in leaves, our result introduces the exciting possibility of application ABA agonists for regulating roots water uptake in field, with a species- and dose dependent manner.


      PubDate: 2015-07-01T14:00:39Z
       
  • Rapid and reproducible determination of active gibberellins in citrus
           tissues by UPLC/ESI-MS/MS
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Matías Manzi , Aurelio Gómez-Cadenas , Vicent Arbona
      Phytohormone determination is crucial to explain the physiological mechanisms during growth and development. Therefore, rapid and precise methods are needed to achieve reproducible determination of phytohormones. Among many others, gibberellins (GAs) constitute a family of complex analytes as most of them share similar structure and chemical properties although only a few hold biological activity (namely GA1; GA3; GA4 and GA7). A method has been developed to extract GAs from plant tissues by mechanical disruption using ultrapure water as solvent and, in this way, ion suppression was reduced whereas sensitivity increased. Using this methodology, the four active GAs were separated and quantified by UPLC coupled to MS/MS using the isotope-labeled internal standards [2H2]-GA1 and [2H2]-GA4. To sum up, the new method provides a fast and reproducible protocol to determine bioactive GAs at low concentrations, using minimal amounts of sample and reducing the use of organic solvents.


      PubDate: 2015-07-01T14:00:39Z
       
  • Regulation of ascorbic acid biosynthesis and recycling during root
           development in carrot (Daucus carota L.)
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Guang-Long Wang , Zhi-Sheng Xu , Feng Wang , Meng-Yao Li , Guo-Fei Tan , Ai-Sheng Xiong
      Ascorbic acid (AsA), also known as vitamin C, is an essential nutrient in fruits and vegetables. The fleshy root of carrot (Daucus carota L.) is a good source of AsA for humans. However, the metabolic pathways and molecular mechanisms involved in the control of AsA content during root development in carrot have not been elucidated. To gain insights into the regulation of AsA accumulation and to identify the key genes involved in the AsA metabolism, we cloned and analyzed the expression of 21 related genes during carrot root development. The results indicate that AsA accumulation in the carrot root is regulated by intricate pathways, of which the l -galactose pathway may be the major pathway for AsA biosynthesis. Transcript levels of the genes encoding l-galactose-1-phosphate phosphatase and l-galactono-1,4-lactone dehydrogenase were strongly correlated with AsA levels during root development. Data from this research may be used to assist breeding for improved nutrition, quality, and stress tolerance in carrots.


      PubDate: 2015-07-01T14:00:39Z
       
  • Transgenic poplar expressing Arabidopsis YUCCA6 exhibits
           
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Qingbo Ke , Zhi Wang , Chang Yoon Ji , Jae Cheol Jeong , Haeng-Soon Lee , Hongbing Li , Bingcheng Xu , Xiping Deng , Sang-Soo Kwak
      YUCCA6, a member of the YUCCA family of flavin monooxygenase-like proteins, is involved in the tryptophan-dependent IAA biosynthesis pathway and responses to environmental cues in Arabidopsis. However, little is known about the role of the YUCCA pathway in auxin biosynthesis in poplar. Here, we generated transgenic poplar (Populus alba × P. glandulosa) expressing the Arabidopsis YUCCA6 gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SY plants). Three SY lines (SY7, SY12 and SY20) were selected based on the levels of AtYUCCA6 transcript. SY plants displayed auxin-overproduction morphological phenotypes, such as rapid shoot growth and retarded main root development with increased root hair formation. In addition, SY plants had higher levels of free IAA and early auxin-response gene transcripts. SY plants exhibited tolerance to drought stress, which was associated with reduced levels of reactive oxygen species. Furthermore, SY plants showed delayed hormone- and dark-induced senescence in detached leaves due to higher photosystem II efficiency and less membrane permeability. These results suggest that the conserved IAA biosynthesis pathway mediated by YUCCA family members exists in poplar.


      PubDate: 2015-07-01T14:00:39Z
       
  • Effects of moist cold stratification on germination, plant growth
           regulators, metabolites and embryo ultrastructure in seeds of Acer
           morrisonense (Sapindaceae)
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Shun-Ying Chen , Shih-Han Chou , Ching-Chu Tsai , Wen-Yu Hsu , Carol C. Baskin , Jerry M. Baskin , Ching-Te Chien , Ling-Long Kuo-Huang
      Breaking of seed dormancy by moist cold stratification involves complex interactions in cells. To assess the effect of moist cold stratification on dormancy break in seeds of Acer morrisonense, we monitored percentages and rates of germination and changes in plant growth regulators, sugars, amino acids and embryo ultrastructure after various periods of cold stratification. Fresh seeds incubated at 25/15 °C for 24 weeks germinated to 61%, while those cold stratified at 5 °C for 12 weeks germinated to 87% in 1 week. Neither exogenous GA3 nor GA4 pretreatment significantly increased final seed germination percentage. Total ABA content of seeds cold stratified for 12 weeks was reduced about 3.3-fold, to a concentration similar to that in germinated seeds (radicle emergence). Endogenous GA3 and GA7 were detected in 8-week and 12-week cold stratified seeds but not in fresh seeds. Numerous protein and lipid bodies were present in the plumule, first true leaves and cotyledons of fresh seeds. Protein and lipid bodies decreased greatly during cold stratification, and concentrations of total soluble sugars and amino acids increased. The major non-polar sugars in fresh seeds were sucrose and fructose, but sucrose increased and fructose decreased significantly during cold stratification. The major free amino acids were proline and tryptophan in fresh seeds, and proline increased and tryptophan decreased during cold stratification. Thus, as dormancy break occurs during cold stratification seeds of A. morrisonense undergo changes in plant growth regulators, proteins, lipids, sugars, amino acids and cell ultrastructure.


      PubDate: 2015-07-01T14:00:39Z
       
  • Overexpression of two R2R3-MYB genes from Scutellaria baicalensis induces
           phenylpropanoid accumulation and enhances oxidative stress resistance in
           transgenic tobacco
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Linjie Qi , Jian Yang , Yuan Yuan , Luqi Huang , Ping Chen
      MYB proteins are involved in many significant physiological and biochemical processes, including regulation of primary and secondary metabolism, flavonoid biosynthesis, response to various biotic and abiotic stresses, hormone synthesis and signal transduction. The functions of R2R3-MYB proteins in Scutellaria baicalensis Georgi under abiotic stress, however, has not been elucidated. To study the molecular mechanism by which MYB2 and MYB7 respond to abiotic stress in S. baicalensis, we analyzed the phenylpropanoid content, growth phenotype, antioxidant enzyme activity and flavonoid synthesis-associated gene expression in SbMYB2 or SbMYB7-overexpressing transgenic tobacco plants after treatment with NaCl, mannitol and abscisic acid (ABA). The transgenic tobacco showed a higher fresh weight than did the wild type (WT) tobacco. In contrast, antioxidant enzyme activity and flavonoid synthesis-related gene expression were markedly higher in WT tobacco after treatment with NaCl, mannitol and ABA, as compared to transgenic plants, This is likely because increased phenylpropanoid accumulation in transgenic tobacco plants played a central role in abiotic stress resistance. These results indicate that overexpression of SbMYB2 or SbMYB7 increased phenylpropanoid accumulation and enhanced NaCl, mannitol and ABA stresses tolerance in transgenic tobacco.
      Graphical abstract image

      PubDate: 2015-07-01T14:00:39Z
       
  • Biochemical characterization of an isoprene synthase from Campylopus
           introflexus (heath star moss)
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Alexandra T. Lantz , Joseph F. Cardiello , Taylor A. Gee , Michaelin G. Richards , Todd N. Rosenstiel , Alison J. Fisher
      Each year, plants emit terragram quantities of the reactive hydrocarbon isoprene (2-methyl-1,3-butadiene) into the earth's atmosphere. In isoprene-emitting plants, the enzyme isoprene synthase (ISPS) catalyzes the production of isoprene from the isoprenoid intermediate dimethylallyl diphosphate (DMADP). While isoprene is emitted from all major classes of land plants, to date ISPSs from angiosperms only have been characterized. Here, we report the identification and initial biochemical characterization of a DMADP-dependent ISPS from the isoprene-emitting bryophyte Campylopus introflexus (heath star moss). The partially-purified C. introflexus ISPS (CiISPS) exhibited a K m for DMADP of 0.37 ± 0.28 mM, a pH optimum of 8.6 ± 0.5, and a temperature optimum of 40 ± 3 °C in vitro. Like ISPSs from angiosperms, the CiISPS required the presence of a divalent cation. However, unlike angiosperm ISPSs, the CiISPS utilized Mn2+ preferentially over Mg2+. Efforts are currently underway in our laboratory to further purify the CiISPS and clone the cDNA sequence encoding this novel enzyme. Our discovery of the first bryophyte ISPS paves the way for future studies concerning the evolutionary origins of isoprene emission in land plants and may help generate new bryophyte model systems for physiological and biochemical research on plant isoprene function.


      PubDate: 2015-07-01T14:00:39Z
       
  • Bisphenol A affects germination and tube growth in Picea meyeri pollen
           through modulating Ca2+ flux and disturbing actin-dependent vesicular
           trafficking during cell wall construction
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Tongjie Chang , Chengyu Fan , Yi Man , Junhui Zhou , Yanping Jing
      Bisphenol A (BPA), a widespread pollutant, is reportedly harmful to humans, animals and plants. However, the effect of BPA on plant pollen tube growth, as well as the mechanism involved, remains unclear. Here, we report that BPA significantly inhibited Picea meyeri pollen germination and tube elongation in a dose-dependent manner. Transmission electron microscopy showed that BPA was detrimental to organelles such as mitochondria and Golgi apparatus. Non-invasive detection revealed that BPA inhibited extracellular Ca2+ influx and promoted intracellular Ca2+ efflux at the pollen tube tip, thereby inducing a dissipated Ca2+ gradient. Fluorescence labeling showed that BPA disorganized actin filaments (AFs), which subsequently led to abnormal vesicle trafficking. Furthermore, BPA reduced the activity of acid phosphatase, a typical exocytosis enzyme. Moreover, Fourier transform infrared (FTIR) analysis and subsequent fluorescence labeling revealed that BPA induced an abnormal deposition of cell wall components, including pectins and callose. Taken together, our results indicate that BPA, a ubiquitous environmental pollutant, disturbs Ca2+ flux in P. meyeri pollen tubes, thus disrupting AF organization, resulting in abnormal actin-dependent vesicle trafficking and further affecting the deposition of cell wall components. These findings provide new insight into the mechanism of BPA toxicity in pollen tube tip growth.


      PubDate: 2015-07-01T14:00:39Z
       
  • Exogenous malic and acetic acids reduce cadmium phytotoxicity and enhance
           cadmium accumulation in roots of sunflower plants
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Barbara Hawrylak-Nowak , Sławomir Dresler , Renata Matraszek
      There is increasing evidence showing that low molecular weight organic acids (LMWOA) are involved in heavy metal resistance mechanisms in plants. The aim of this study was to investigate the effects of exogenous malic (MA) or acetic (AA) acids on the toxicity and accumulation of cadmium (Cd) in sunflower (Helianthus annuus L.). For this purpose, plants were grown in hydroponics under controlled conditions. Single Cd stress (5 μM Cd for 14 days) induced strong phytotoxic effects, as indicated by a decrease in all growth parameters, concentration of photosynthetic pigments, and root activity, as well as a high level of hydrogen peroxide (H2O2) accumulation. Exogenous MA or AA (250 or 500 μM) applied to the Cd-containing medium enhanced the accumulation of Cd by the roots and limited Cd translocation to the shoots. Moreover, the MA or AA applied more or less reduced Cd phytotoxicity by increasing the growth parameters, photosynthetic pigment concentrations, decreasing accumulation of H2O2, and improving the root activity. Of the studied organic acids, MA was much more efficient in mitigation of Cd toxicity than AA, probably by its antioxidant effects, which were stronger than those of AA. Plant response to Cd involved decreased production of endogenous LMWOA, probably as a consequence of severe Cd toxicity. The addition of MA or AA to the medium increased endogenous accumulation of LMWOA, especially in the roots, which could be beneficial for plant metabolism. These results imply that especially MA may be involved in the processes of Cd uptake, translocation, and tolerance in plants.


      PubDate: 2015-07-01T14:00:39Z
       
  • Melatonin in Arabidopsis thaliana acts as plant growth regulator at low
           concentrations and preserves seed viability at high concentrations
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Ismaél Gatica Hernández , Federico José Vicente Gomez , Soledad Cerutti , María Verónica Arana , María Fernanda Silva
      Since the discovery of melatonin in plants, several roles have been described for different species, organs, and developmental stages. Arabidopsis thaliana, being a model plant species, is adequate to contribute to the elucidation of the role of melatonin in plants. In this work, melatonin was monitored daily by UHPLC-MS/MS in leaves, in order to study its diurnal accumulation as well as the effects of natural and artificial light treatments on its concentration. Furthermore, the effects of exogenous application of melatonin to assess its role in seed viability after heat stress and as a regulator of growth and development of vegetative tissues were evaluated. Our results indicate that melatonin contents in Arabidopsis were higher in plants growing under natural radiation when compared to those growing under artificial conditions, and its levels were not diurnally-regulated. Exogenous melatonin applications prolonged seed viability after heat stress conditions. In addition, melatonin applications retarded leaf senescence. Its effects as growth promoter were dose and tissue–dependent; stimulating root growth at low concentrations and decreasing leaf area at high doses.


      PubDate: 2015-07-01T14:00:39Z
       
  • Brassinosteroids are involved in controlling sugar unloading in Vitis
           vinifera ‘Cabernet Sauvignon’ berries during véraison
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Fan Xu , Zhu-mei Xi , Hui Zhang , Cheng-jun Zhang , Zhen-wen Zhang
      Sugar unloading in grape berries is a crucial step in the long-distance transport of carbohydrates from grapevine leaves to berries. Brassinosteroids (BRs) mediate many physiological processes in plants including carbohydrate metabolism. Here, ‘Cabernet Sauvignon’ (Vitis vinifera L.) grape berries cultivated in clay loam fields were treated with an exogenous BR (24-epibrassinolide; EBR), a BR synthesis inhibitor (brassinazole; Brz), Brz + EBR (sprayed with EBR 24 h after a Brz treatment), and deionized water (control) at the onset of véraison. The EBR treatment sharply increased the soluble sugars content in the berries, but decreased it in the skins. The EBR and Brz + EBR treatments significantly promoted the activities of both invertases (acidic and neutral) and sucrose synthase (sucrolytic) at various stages of ripening. The mRNA levels of genes encoding sucrose metabolic invertase (VvcwINV), and monosaccharide (VvHT3, 4, 5 and 6) and disaccharide (VvSUC12 and 27) transporters were increased by the EBR and/or Brz + EBR treatments. Generally, the effects of the Brz treatment on the measured targets contrasted with the effects of the EBR treatments. The EBR and Brz treatments inhibited the biosynthesis of the endogenous BRs 6-deoxocastastarone and castasterone. Both EBR and Brz + EBR treatments increased the brassinolide contents, down-regulated the expression of genes encoding BRs biosynthetic enzymes BRASSINOSTEROID-6-OXIDASE and DWARF1, (VvBR6OX1 and VvDWF1) and induced BR receptor gene BRASSINOSTEROID INSENSITIVE 1 (VvBRI1) expression in deseeded berries. Together, these results show that BRs are involved in controlling sugar unloading in grape berries during véraison.
      Graphical abstract image

      PubDate: 2015-07-01T14:00:39Z
       
  • Transgenic poplar expressing the pine GS1a show alterations in nitrogen
           homeostasis during drought
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Juan Jesús Molina-Rueda , Edward G. Kirby
      Transgenic hybrid poplars engineered to express ectopically the heterologous pine cytosolic GS1a display a number of significant pleiotropic phenotypes including enhanced growth, enhanced nitrogen use efficiency, and resistance to drought stress. The present study was undertaken in order to assess mechanisms whereby ectopic expression of pine GS1a in transgenic poplars results in enhanced agronomic phenotypes. Microarray analysis using the Agilent Populus whole genome array has allowed identification of genes differentially expressed between wild type (WT) and GS transgenics in four tissues (sink leaves, source leaves, stems, and roots) under three growth conditions (well-watered, drought, and recovery). Analysis revealed that differentially expressed genes in functional categories related to nitrogen metabolism show a trend of significant down-regulation in GS poplars compared to the WT, including genes encoding nitrate and nitrite reductases. The down-regulation of these genes was verified using qPCR, and downstream effects were further tested using NR activity assays. Results suggest that higher glutamine levels in GS transgenics regulate nitrate uptake and reduction. Transcript levels of nitrogen-related genes in leaves, including GS/GOGAT cycle enzymes, aspartate aminotransferase, GABA shunt enzymes, photorespiration enzymes, asparagine synthetase, phenylalanine ammonia lyase, isocitrate dehydrogenase, and PII, were also assessed using qPCR revealing significant differences between GS poplars and the WT. Moreover, metabolites related to these differentially expressed genes showed alterations in levels, including higher levels of GABA, hydroxyproline, and putrescine in the GS transgenic. These alterations in nitrogen homeostasis offer insights into mechanisms accounting for drought tolerance observed in GS poplars.


      PubDate: 2015-07-01T14:00:39Z
       
  • Phenotypic plasticity of sun and shade ecotypes of Stellaria longipes in
           response to light quality signaling, gibberellins and auxin
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Leonid V. Kurepin , Richard P. Pharis , R.J. Neil Emery , David M. Reid , C.C. Chinnappa
      Stellaria longipes plant communities (ecotypes) occur in several environmentally distinct habitats along the eastern slopes of southern Alberta's Rocky Mountains. One ecotype occurs in a prairie habitat at ∼1000 m elevation where Stellaria plants grow in an environment in which the light is filtered by taller neighbouring vegetation, i.e. sunlight with a low red to far-red (R/FR) ratio. This ecotype exhibits a high degree of phenotypic plasticity by increasing stem elongation in response to the low R/FR ratio light signal. Another Stellaria ecotype occurs nearby at ∼2400 m elevation in a much cooler alpine habitat, one where plants rarely experience low R/FR ratio shade light. Stem elongation of plants is largely regulated by gibberellins (GAs) and auxin, indole-3-acetic acid (IAA). Shoots of the prairie ecotype plants show increased IAA levels under low R/FR ratio light and they also increase their stem growth in response to applied IAA. The alpine ecotype plants show neither response. Plants from both ecotypes produce high levels of growth-active GA1 under low R/FR ratio light, though they differ appreciably in their catabolism of GA1. The alpine ecotype plants exhibit very high levels of GA8, the inactive product of GA1 metabolism, under both normal and low R/FR ratio light. Alpine origin plants may de-activate GA1 by conversion to GA8 via a constitutively high level of expression of the GA2ox gene, thereby maintaining their dwarf phenotype and exhibiting a reduced phenotypic plasticity in terms of shoot elongation. In contrast, prairie plants exhibit a high degree of phenotypic plasticity, using low R/FR ratio light-mediated changes in GA and IAA concentrations to increase shoot elongation, thereby accessing direct sunlight to optimize photosynthesis. There thus appear to be complex adaptation strategies for the two ecotypes, ones which involve modifications in the homeostasis of endogenous hormones.


      PubDate: 2015-07-01T14:00:39Z
       
  • Overexpression of a NF-YB3 transcription factor from Picea wilsonii
           confers tolerance to salinity and drought stress in transformed
           Arabidopsis thaliana
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Tong Zhang , Dun Zhang , Yajing Liu , Chaobing Luo , Yanni Zhou , Lingyun Zhang
      Nuclear factor Y (NF-Y) is a highly conserved transcription factor comprising NF-YA, NF-YB and NF-YC subunits. To date, the roles of NF-Y subunit in plant still remain elusive. In this study, a subunit NF-YB (PwNF-YB3), was isolated from Picea wilsonii Mast. and its role was studied. PwNF-YB3 transcript was detected in all vegetative and reproductive tissues with higher levels in stem and root and was greatly induced by salinity, heat and PEG but not by cold and ABA treatment. Over-expression of PwNF-YB3 in Arabidopsis showed a significant acceleration in the onset of flowering and resulted in more vigorous seed germination and significant tolerance for seedlings under salinity, drought and osmotic stress compared with wild type plants. Transcription levels of salinity-responsive gene (SOS3) and drought-induced gene (CDPK1) were substantially higher in transgenic Arabidopsis than in wild-type plants. Importantly, CBF pathway markers (COR15B, KIN1, LEA76), but not ABA pathway markers CBF4, were greatly induced under condition of drought. The nuclear localization showed that NF-YB3 acted as a transcription factor. Taken together, the data provide evidence that PwNF-YB3 positively confers significant tolerance to salt, osmotic and drought stress in transformed Arabidopsis plants probably through modulating gene regulation in CBF-dependent pathway.


      PubDate: 2015-07-01T14:00:39Z
       
  • Exogenous adenosine 5′-phosphoramidate behaves as a signal molecule
           in plants; it augments metabolism of phenylpropanoids and salicylic
           acid in Arabidopsis thaliana seedlings
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Małgorzata Pietrowska-Borek , Katarzyna Nuc , Andrzej Guranowski
      Cells contain various congeners of the canonical nucleotides. Some of these accumulate in cells under stress and may function as signal molecules. Their cellular levels are enzymatically controlled. Previously, we demonstrated a signaling function for diadenosine polyphosphates and cyclic nucleotides in Arabidopsis thaliana and grape, Vitis vinifera. These compounds increased the expression of genes for and the specific activity of enzymes of phenylpropanoid pathways resulting in the accumulation of certain products of these pathways. Here, we show that adenosine 5′-phosphoramidate, whose level can be controlled by HIT-family proteins, induced similar effects. This natural nucleotide, when added to A. thaliana seedlings, activated the genes for phenylalanine:ammonia lyase, 4-coumarate:coenzyme A ligase, cinnamate-4-hydroxylase, chalcone synthase, cinnamoyl-coenzyme A:NADP oxidoreductase and isochorismate synthase, which encode proteins catalyzing key reactions of phenylpropanoid pathways, and caused accumulation of lignins, anthocyanins and salicylic acid. Adenosine 5′-phosphofluoridate, a synthetic congener of adenosine 5′-phosphoramidate, behaved similarly. The results allow us to postulate that adenosine 5′-phosphoramidate should be considered as a novel signaling molecule.


      PubDate: 2015-07-01T14:00:39Z
       
  • Physiological and molecular analyses of black and yellow seeded Brassica
           napus regulated by 5-aminolivulinic acid under chromium stress
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Rafaqat A. Gill , Basharat Ali , Faisal Islam , Muhammad A. Farooq , Muhammad B. Gill , Theodore M. Mwamba , Weijun Zhou
      Brassica napus L. is a promising oilseed crop among the oil producing species. So, it is prime concern to screen the metal tolerant genotypes in order to increase the oilseed rape production through the utilization of pollutant soil regimes. Nowadays, use of plant growth regulators against abiotic stress is one of the major objectives of researchers. In this study, an attempt was carried out to analyze the pivotal role of exogenously applied 5-amenolevulinic acid (ALA) on alleviating chromium (Cr)-toxicity in black and yellow seeded B. napus. Plants of two cultivars (ZS 758 – a black seed type, and Zheda 622 – a yellow seed type) were treated with 400 μM Cr with or without 15 and 30 mg/L ALA. Results showed that exogenously applied ALA improved the plant growth and increased ALA contents; however, it decreased the Cr concentration in B. napus leaves under Cr-toxicity. Moreover, exogenous ALA reduced oxidative stress by up-regulating antioxidant enzyme activities and their related gene expression. Further, results suggested that stress responsive protein's transcript level such as HSP90-1 and MT-1 were increased under Cr stress alone in both cultivars. Exogenously applied ALA further enhanced the expression rate in both genotypes and obviously results were found in favor of cultivar ZS 758. The ultrastructural changes were observed more obvious in yellow seeded than black seeded cultivar; however, exogenously applied ALA helped the plants to recover their cell turgidity under Cr stress. The present study describes a detailed molecular mechanism how ALA regulates the plant growth by improving antioxidant machinery and related transcript levels, cellular modification as well as stress related genes expression under Cr-toxicity.


      PubDate: 2015-07-01T14:00:39Z
       
  • Mitochondrial structural and antioxidant system responses to aging in oat
           (Avena sativa L.) seeds with different moisture contents
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Fangshan Xia , Xianguo Wang , Manli Li , Peisheng Mao
      We observed the relationship between lifespan and mitochondria, including antioxidant systems, ultrastructure, and the hydrogen peroxide and malondialdehyde contents in 4 h imbibed oat (Avena sativa L.) seeds that were aged with different moisture contents (4%, 10% and 16%) for 0 (the control), 8, 16, 24, 32 and 40 d at 45 °C. The results showed that the decline in the oat seed vigor and in the integrity of the mitochondrial ultrastructure occurred during the aging process, and that these changes were enhanced by higher moisture contents. Mitochondrial antioxidants in imbibed oat seeds aged with a 4% moisture content were maintained at higher levels than imbibed oat seeds aged with a 10% and 16% moisture content. These results indicated that the levels of mitochondrial antioxidants and malondialdehyde after imbibition were related to the integrity of the mitochondrial membrane in aged oat seeds. The scavenging role of mitochondrial superoxide dismutase was inhibited in imbibed oat seeds aged at the early stage. Monodehydroascorbate reductase and dehydroascorbate reductase played more important roles than glutathione reductase in ascorbate regeneration in aged oat seeds during imbibition.


      PubDate: 2015-07-01T14:00:39Z
       
  • Age-related changes in protein metabolism of beech (Fagus sylvatica L.)
           seeds during alleviation of dormancy and in the early stage of germination
           
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Ewelina Ratajczak , Ewa M. Kalemba , Stanislawa Pukacka
      The long-term storage of seeds generally reduces their viability and vigour. The aim of this work was to evaluate the effect of long-term storage on beech (Fagus sylvatica L.) seeds at optimal conditions, over 9 years, on the total and soluble protein levels and activity of proteolytic enzymes, including endopeptidases, carboxypeptidases and aminopeptidases, as well as free amino acid levels and protein synthesis, in dry seeds, after imbibition and during cold stratification leading to dormancy release and germination. The same analyses were conducted in parallel on seeds gathered from the same tree in the running growing season and stored under the same conditions for only 3 months. The results showed that germination capacity decreased from 100% in freshly harvested seeds to 75% in seeds stored for 9 years. The levels of total and soluble proteins were highest in freshly harvested seeds and decreased significantly during storage, these proportions were retained during cold stratification and germination of seeds. Significant differences between freshly harvested and stored seeds were observed in the activities of proteolytic enzymes, including endopeptidases, aminopeptidases and carboxypeptidases, and in the levels of free amino acids. The neosynthesis of proteins during dormancy release and in the early stage of seed germination was significantly weaker in stored seeds. These results confirm the importance of protein metabolism for seed viability and the consequences of its reduction during seed ageing.


      PubDate: 2015-07-01T14:00:39Z
       
  • Proline over-accumulation alleviates salt stress and protects
           photosynthetic and antioxidant enzyme activities in transgenic sorghum
           [Sorghum bicolor (L.) Moench]
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): P. Surender Reddy , Gadi Jogeswar , Girish K. Rasineni , M. Maheswari , Attipalli R. Reddy , Rajeev K. Varshney , P.B. Kavi Kishor
      Shoot-tip derived callus cultures of Sorghum bicolor were transformed by Agrobacterium tumefaciens as well as by bombardment methods with the mutated pyrroline-5-carboxylate synthetase (P5CSF129A) gene encoding the key enzyme for proline biosynthesis from glutamate. The transgenics were selfed for three generations and T4 plants were examined for 100 mM NaCl stress tolerance in pot conditions. The effect of salt stress on chlorophyll and carotenoid contents, photosynthetic rate, stomatal conductance, internal carbon dioxide concentration, transpiration rates, intrinsic transpiration and water use efficiencies, proline content, MDA levels, and antioxidant enzyme activities were evaluated in 40-day-old transgenic lines and the results were compared with untransformed control plants. The results show that chlorophyll content declines by 65% in untransformed controls compared to 30–38% loss (significant at P < 0.05) in transgenics but not carotenoid levels. Photosynthetic rate (PSII activity) was reduced in untransformed controls almost completely, while it declined by 62–88% in different transgenic lines. Salinity induced ca 100% stomatal closure in untransformed plants, while stomatal conductance was decreased only by 64–81% in transgenics after 4 days. The intercellular CO2 decreased by ca 30% in individual transgenic lines. Malondialdehyde (MDA) content was lower in transgenics compared to untransformed controls. The activities of superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6) and glutathione reductase (GR; EC1.8.1.7) were quantified in leaves exposed to 100 mM NaCl stress and found higher in transgenics. The results suggest that transgenic lines were able to cope better with salt stress than untransformed controls by protecting photosynthetic and antioxidant enzyme activities.


      PubDate: 2015-07-01T14:00:39Z
       
  • Exogenously applied selenium reduces oxidative stress and induces heat
           tolerance in spring wheat
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Muhammad Iqbal , Iqbal Hussain , Hena Liaqat , M. Arslan Ashraf , Rizwan Rasheed , Aziz Ur Rehman
      Heat stress (HS) is a worldwide threat to productivity of wheat, especially in arid and semiarid regions of the world. Earlier studies suggested the beneficial effects of selenium (Se) on the growth of some crop species grown under stressful environments. In the present study, we assessed whether Se application could increase antioxidative potential, and thus enhance tolerance to heat in wheat at the sensitive stage i.e., heading stage. At the heading stage, after foliar application of sodium selenate solutions (0, 2 and 4 mg Se L−1), the plants of wheat cultivars, namely Chakwal-97 (drought tolerant) and Faisalabad-08 (drought sensitive), were subjected to HS (38 ± 2 °C). The HS significantly altered antioxidative potential, affected growth, photosynthetic pigments and grain yield in both cultivars. Exogenous application of low (2 mg L−1) Se increased chlorophyll a and total chlorophyll contents and modulated the growth of wheat plants under HS. However, high concentration (4 mg L−1) of Se was much more effective in increasing grains per spike and grain yield in heat stressed plants of both wheat cultivars. Exogenous Se increased both enzymatic (catalase and ascorbate peroxidase activities) and non-enzymatic (carotenoids, anthocyanins and ascorbic acid contents) antioxidants while decreased oxidants (hydrogen peroxide and malondialdehyde contents) under HS in both wheat cultivars. In conclusion, foliar application of Se (4 mg L−1) was much more effective in mitigating the deleterious effects of HS on grain yield of wheat plants. The results suggested that Se-mediated up-regulation of antioxidative system (both enzymatic and non-enzymatic) helped the wheat plants to increase fertility, and hence avoid reduction of grain yield under HS.


      PubDate: 2015-07-01T14:00:39Z
       
  • Systemic regulation of photosynthetic function in field-grown sorghum
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Tao Li , Yujun Liu , Lei Shi , Chuangdao Jiang
      The photosynthetic characteristics of developing leaves of plants grown under artificial conditions are, to some extent, regulated systemically by mature leaves; however, whether systemic regulation of photosynthesis occurs in field-grown crops is unclear. To explore this question, we investigated the effects of planting density on growth characteristics, gas exchange, leaf nitrogen concentration and chlorophyll a fluorescence in field-grown sorghum (Sorghum bicolor L.). Our results showed that close planting resulted in a marked decline in light intensity in lower canopy. Sorghum plants grown at a high planting density had lower net photosynthetic rate (P n), stomatal conductance (G s), and transpiration rate (E) than plants grown at a low planting density. Moreover, in the absence of mineral deficiency, close planting induced a slight increase in leaf nitrogen concentration. The decreased photosynthesis in leaves of the lower canopy at high planting density was caused mainly by the low light. However, newly developed leaves exposed to high light in the upper canopy of plants grown at high planting density also exhibited a distinct decline in photosynthesis relative to plants grown at low planting density. Based on these results, the photosynthetic function of the newly developed leaves in the upper canopy was not determined fully by their own high light environment. Accordingly, we suggest that the photosynthetic function of newly developed leaves in the upper canopy of field-grown sorghum plants is regulated systemically by the lower canopy leaves. The differences in systemic regulation of photosynthesis were also discussed between field conditions and artificial conditions.
      Graphical abstract image

      PubDate: 2015-07-01T14:00:39Z
       
  • Genome-wide analysis and expression profiling of DNA-binding with one zinc
           finger (Dof) transcription factor family in potato
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Jelli Venkatesh , Se Won Park
      DNA-binding with one finger (Dof) domain proteins are a multigene family of plant-specific transcription factors involved in numerous aspects of plant growth and development. Here, we report a genome-wide search for Solanum tuberosum Dof (StDof) genes and their expression profiles at various developmental stages and in response to various abiotic stresses. In addition, a complete overview of Dof gene family in potato is presented, including the gene structures, chromosomal locations, cis-regulatory elements, conserved protein domains, and phylogenetic inferences. Based on the genome-wide analysis, we identified 35 full-length protein-coding StDof genes, unevenly distributed on 10 chromosomes. Phylogenetic analysis with Dof members from diverse plant species showed that StDof genes can be classified into four subgroups (StDofI, II, III, and IV). qPCR expression analysis of StDof gene transcripts showed the distinct expression patterns of StDof genes in various potato organs, and tuber developmental stages analyzed. Many StDof genes were upregulated in response to drought, salinity, and ABA treatments. Overall, the StDof gene expression pattern and the number of over-represented cis-acting elements in the promoter regions of the StDof genes indicate that most of the StDof genes have redundant functions. The detailed genomic information and expression profiles of the StDof gene homologs in the present study provide opportunities for functional analyses to unravel the genes' exact role in plant growth and development as well as in abiotic stress tolerance.


      PubDate: 2015-07-01T14:00:39Z
       
  • UV-B induction of the E3 ligase ARIADNE12 depends on CONSTITUTIVELY
           PHOTOMORPHOGENIC 1
    • Abstract: Publication date: Available online 23 March 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Lisi Xie , Christina Lang-Mladek , Julia Richter , Neha Nigam , Marie-Theres Hauser
      The UV-B inducible ARIADNE12 (ARI12) gene of Arabidopsis thaliana is a member of the RING-between-RING (RBR) family of E3 ubiquitin ligases for which a novel ubiquitination mechanism was identified in mammalian homologs. This RING-HECT hybrid mechanism needs a conserved cysteine which is replaced by serine in ARI12 and might affect the E3 ubiquitin ligase activity. We have shown that under photomorphogenic UV-B, ARI12 is a downstream target of the classical ultraviolet B (UV-B) UV RESISTANCE LOCUS 8 (UVR8) pathway. However, under high fluence rate of UV-B ARI12 was induced independently of UVR8 and the UV-A/blue light and red/far-red photoreceptors. A key component of several light signaling pathways is CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). Upon UV-B COP1 is trapped in the nucleus through interaction with UVR8 permitting the activation of genes that regulate the biosynthesis of UV-B protective metabolites and growth adaptations. To clarify the role of COP1 in the regulation of ARI12 mRNA expression and ARI12 protein stability, localization and interaction with COP1 was assessed with and without UV-B. We found that COP1 controls ARI12 in white light, low and high fluence rate of UV-B. Furthermore we show that ARI12 is indeed an E3 ubiquitin ligase which is mono-ubiquitinated, a prerequisite for the RING-HECT hybrid mechanism. Finally, genetic analyses with transgenes expressing a genomic pmARI12:ARI12-GFP construct confirm the epistatic interaction between COP1 and ARI12 in growth responses to high fluence rate UV-B.


      PubDate: 2015-04-03T17:51:32Z
       
 
 
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