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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  [3032 journals]
  • Comparison of silicon nanoparticles and silicate treatments in fenugreek
    • Authors: Sanam Nazaralian; Ahmad Majd; Saeed Irian; Farzaneh Najafi; Farrokh Ghahremaninejad; Tommy Landberg; Maria Greger
      Pages: 25 - 33
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Sanam Nazaralian, Ahmad Majd, Saeed Irian, Farzaneh Najafi, Farrokh Ghahremaninejad, Tommy Landberg, Maria Greger
      Silicon (Si) fertilization improves crop cultivation and is commonly added in the form of soluble silicates. However, most natural plant-available Si originates from plant formed amorphous SiO2 particles, phytoliths, similar to SiO2-nanoparticles (SiNP). In this work we, therefore, compared the effect by sodium silicate and that of SiNP on Si accumulation, activity of antioxidative stress enzymes catalase, peroxidase, superoxide dismutase, lignification of xylem cell walls and activity of phenylalanine ammonia-lyase (PAL) as well as expression of genes for the putative silicon transporter (PST), defensive (Tfgd 1) and phosphoenolpyruvate carboxykinase (PEPCK) and protein in fenugreek (Trigonella foenum-graecum L.) grown in hydroponics. The results showed that Si was taken up from both silicate and SiNP treatments and increasing sodium silicate addition increased the translocation of Si to the shoot, while this was not shown with increasing SiNP addition. The silicon transporter PST was upregulated at a greater level when sodium silicate was added compared with SiNP addition. There were no differences in effects between sodium silicate and SiNP treatments on the other parameters measured. Both treatments increased the uptake and accumulation of Si, xylem cell wall lignification, cell wall thickness, PAL activity and protein concentration in seedlings, while there was no effect on antioxidative enzyme activity. Tfgd 1 expression was strongly downregulated in leaves at Si addition. The similarity in effects by silicate and SiNP would be due to that SiNP releases silicate, which may be taken up, shown by a decrease in SiNP particle size with time in the medium.

      PubDate: 2017-03-17T10:05:08Z
      DOI: 10.1016/j.plaphy.2017.03.009
      Issue No: Vol. 115 (2017)
       
  • Early response of wheat antioxidant system with special reference to
           Fusarium head blight stress
    • Authors: Valentina Spanic; Marija Viljevac Vuletic; Ivan Abicic; Tihana Marcek
      Pages: 34 - 43
      Abstract: Publication date: Available online 14 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Valentina Spanic, Marija Viljevac Vuletic, Ivan Abicic, Tihana Marcek
      Fusarium head blight (FHB) is a destructive fungal disease of wheat (Triticum aestivum L.) that causes significant grain yield losses and end-use quality reduction associated with contamination by the mycotoxin deoxynivalenol (DON). Three winter wheat varieties (‘Vulkan’, ‘Kraljica’ and ‘Golubica’) were screened for FHB resistance using artificial inoculation technique under field conditions. The aim of this study was to examine a relationship between FHB resistance and the effectiveness of enzyme antioxidant system of wheat varieties under different sampling times (3, 15, 24, 48, 96, 120 and 336 hai). In the time-course experiments FHB-resistant variety ‘Vulkan’ showed rapid induction of ascorbate peroxidase (APX) and polyphenol oxidase (PPO) activity in the early stages after infection (3 hai) and it seems that in ‘Vulkan’ FHB-resistance is associated with antioxidative enzymes activity. Moderately FHB resistant variety ‘Kraljica’ showed the higher guaiacol peroxidase (POD) activity and higher H2O2 content after 24 hai, increased malondialdehyde (MDA) content at the beginning of infection (3, 15 hai) while induction of catalase (CAT), APX and PPO was delayed. FHB-susceptible variety ‘Golubica’ involved antioxidant enzymes in defense response much later. Based on our results the activity of antioxidant enzymes (APX and PPO) was more pronounced in ‘Vulkan’ than in FHB-medium resistant variety ‘Kraljica’ and FHB-susceptible ‘Golubica’. The differences in antioxidant response of wheat varieties under Fusarium infestation could be the result of genetic properties.

      PubDate: 2017-03-17T10:05:08Z
      DOI: 10.1016/j.plaphy.2017.03.010
      Issue No: Vol. 115 (2017)
       
  • Apoplastic gamma-glutamyl transferase activity encoded by GGT1 and GGT2 is
           important for vegetative and generative development
    • Authors: Sabrina Giaretta; Dinesh Prasad; Ilaria Forieri; Teofilo Vamerali; Anna Rita Trentin; Markus Wirtz; Rüdiger Hell; Antonio Masi
      Pages: 44 - 56
      Abstract: Publication date: Available online 10 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Sabrina Giaretta, Dinesh Prasad, Ilaria Forieri, Teofilo Vamerali, Anna Rita Trentin, Markus Wirtz, Rüdiger Hell, Antonio Masi
      Gamma-glutamyl transferase (GGT; EC 2.3.2.2) is the only enzyme capable of degrading glutathione (GSH) in extra-cytosolic spaces. In plant cells, the GGT1 and GGT2 isoforms are located in the apoplast, bound respectively to the cell wall and the plasma membrane. GGT1 is expressed throughout plants, mainly in the leaves and vascular system, while GGT2 is more specifically expressed in seeds and trichomes, and weakly in roots. Their role in plant physiology remains to be clarified, however. Obtaining the ggt1/ggt2 double mutant can offer more clues than the corresponding single mutants, and to prevent any compensatory expression between the two isoforms. In this work, ggt1/ggt2 RNAi (RNA interference) lines were generated and characterized in the tissues where both isoforms are expressed. The seed yield was lower in the ggt1/ggt2 RNAi plants due to the siliques being fewer in number and shorter in length, with no changes in thiols and sulfur compounds. Proline accumulation and delayed seed germination were seen in one line. There were also fewer trichomes (which contain high levels of GSH) in the RNAi lines than in the wild type, and the root elongation rate was slower. In conclusion, apoplastic GGT silencing induces a decrease in the number of organs with a high GSH demand (seeds and trichomes) as a result of resource reallocation to preserve integrity and composition.
      Graphical abstract image

      PubDate: 2017-03-17T10:05:08Z
      DOI: 10.1016/j.plaphy.2017.03.007
      Issue No: Vol. 115 (2017)
       
  • Thermal stress impacts reproductive development and grain yield in rice
    • Authors: Muhammad Shakeel Arshad; Muhammad Farooq; Folkard Asch; Jagadish S.V. Krishna; P.V. Vara Prasad; Kadambot H.M. Siddique
      Pages: 57 - 72
      Abstract: Publication date: Available online 16 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Muhammad Shakeel Arshad, Muhammad Farooq, Folkard Asch, Jagadish S.V. Krishna, P.V. Vara Prasad, Kadambot H.M. Siddique
      Rice is highly sensitive to temperature stress (cold and heat), particularly during the reproductive and grain-filling stages. In this review, we discuss the effects of low- and high-temperature sensitivity in rice at various reproductive stages (from meiosis to grain development) and propose strategies for improving the tolerance of rice to terminal thermal stress. Cold stress impacts reproductive development through (i) delayed heading, due to its effect on anther respiration, which increases sucrose accumulation, protein denaturation and asparagine levels, and decreases proline accumulation, (ii) pollen sterility owing to tapetal hypertrophy and related nutrient imbalances, (iii) reduced activity of cell wall bound invertase in the tapetum of rice anthers, (iv) impaired fertilization due to inhibited anther dehiscence, stigma receptivity and ability of the pollen tube to germinate through the style towards the ovary, and (v) floret sterility, which increases grain abortion, restricts grain size, and thus reduces grain yield. Heat stress affects grain formation and development through (i) poor anther dehiscence due to restricted closure of the locules, leading to reduced pollen dispersal and fewer pollen on the stigma, (ii) changes in pollen proteins resulting in significant reductions in pollen viability and pollen tube growth, leading to spikelet sterility, (iii) delay in heading, (iv) reduced starch biosynthesis in developing grain, which reduces starch accumulation, (v) increased chalkiness of grain with irregular and round-shaped starch granules, and (vi) a shortened grain-filling period resulting in low grain weight. However, physiological and biotechnological tools, along with integrated management and adaptation options, as well as conventional breeding, can help to develop new rice genotypes possessing better grain yield under thermal stress during reproductive and grain-filling phases.

      PubDate: 2017-03-17T10:05:08Z
      DOI: 10.1016/j.plaphy.2017.03.011
      Issue No: Vol. 115 (2017)
       
  • A barley homolog of yeast ATG6 is involved in multiple abiotic stress
           responses and stress resistance regulation
    • Authors: Xiaowei Zeng; Zhanghui Zeng; Cuicui Liu; Weiyi Yuan; Ning Hou; Hongwu Bian; Muyuan Zhu; Ning Han
      Pages: 97 - 106
      Abstract: Publication date: Available online 19 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Xiaowei Zeng, Zhanghui Zeng, Cuicui Liu, Weiyi Yuan, Ning Hou, Hongwu Bian, Muyuan Zhu, Ning Han
      Autophagy is a highly conserved degradation pathway among eukaryote cells, which can recycle damaged or unwanted cell materials upon encountering stress conditions. As a key component of the Class III PI3K kinase complex, ATG6/Beclin-1 is essential for autophagosome formation. In this study, we isolated a putative HvATG6 gene in barley genome. The protein encoded by HvATG6 shares high sequence identity to ATG6 orthologs in rice and wheat, and has a typical autophagy-specific domain containing segments of repeated β-sheet-α-helix. The expression of HvATG6 protein restored the appearance of autophagosomes in yeast atg6 mutant, indicating that HvATG6 complements the deficiency of yeast ATG6 protein in autophagy. Punctate florescence signals, considered as the PAS for autophagosome initiation, were observed in the cytoplasm of cells when HvATG6-GFP fusion construct was transformed into barley protoplast. Furthermore, the expression of HvATG6 was upregulated by various abiotic stresses including dark, H2O2 treatment, nitrogen deficiency, high salinity, drought, low temperature and toxic aluminum. Knockdown of HvATG6 in barley leaves through barley strip mosaic virus (BSMV)-induced gene silencing led to accelerated yellowing under dark and H2O2 treatments. Based on the above findings, we propose that barley ATG6 plays the similar role as other plant ATG6 orthologs, and might be involved in stress-induced autophagy process.

      PubDate: 2017-03-21T19:17:30Z
      DOI: 10.1016/j.plaphy.2017.03.013
      Issue No: Vol. 115 (2017)
       
  • Isolation and characterization of a novel chalcone synthase gene family
           from mulberry
    • Authors: Chuanhong Wang; Shuang Zhi; Changying Liu; Fengxiang Xu; Aichun Zhao; Xiling Wang; Xing Tang; Zhengang Li; Ping Huang; Maode Yu
      Pages: 107 - 118
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Chuanhong Wang, Shuang Zhi, Changying Liu, Fengxiang Xu, Aichun Zhao, Xiling Wang, Xing Tang, Zhengang Li, Ping Huang, Maode Yu
      Chalcone synthase (CHS) is the pivotal enzyme that catalyzes the first committed step of the phenylpropanoid pathway leading to flavonoids. Here, five CHS genes were determined in mulberry (Morus atropurpurea Roxb.). Interestingly, phylogenetic analysis tended to group three MaCHSs in the stilbene synthase (STS) family and initially annotated these as MaSTSs. A co-expression system that harbored a 4-coumarate:CoA ligase gene and one of the candidate genes was established to determine the functions of this novel gene family. The fermentation result demonstrated that MaSTS in fact encoded a CHS enzyme, and was consequently retermed MaCHS. Tissue-specific expression analysis indicated that MaCHS1/MaCHS2 was highly abundant in fruit, and MaCHS4 had significant expression in root bark, stem bark and old leaves, while MaCHS3 and MaCHS5 were more expressed in old leaves. Subcellular localization experiments showed that MaCHS was localized to the cytoplasm. Transcription levels suggested MaCHS genes were involved in a series of defense responses. Over-expression of MaCHS in transgenic tobacco modified the metabolite profile, and resulted in elevated tolerance to a series of environmental stresses. This study comprehensively evaluated the function of MaCHS genes and laid the foundation for future research on MaCHS in mulberry.

      PubDate: 2017-03-28T15:42:25Z
      DOI: 10.1016/j.plaphy.2017.03.014
      Issue No: Vol. 115 (2017)
       
  • Approaches in modulating proline metabolism in plants for salt and drought
           stress tolerance: Phytohormones, mineral nutrients and transgenics
    • Authors: Tasir S. Per; Nafees A. Khan; Palakolanu Sudhakar Reddy; Asim Masood; Mirza Hasanuzzaman; M. Iqbal R. Khan; Naser A. Anjum
      Pages: 126 - 140
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Tasir S. Per, Nafees A. Khan, Palakolanu Sudhakar Reddy, Asim Masood, Mirza Hasanuzzaman, M. Iqbal R. Khan, Naser A. Anjum
      Major abiotic stress factors such as salt and drought adversely affect important physiological processes and biochemical mechanisms and cause severe loss in crop productivity worldwide. Plants develop various strategies to stand healthy against these stress factors. The accumulation of proline (Pro) is one of the striking metabolic responses of plants to salt and drought stress. Pro biosynthesis and signalling contribute to the redox balance of cell under normal and stressful conditions. However, literature is meager on the sustainable strategies potentially fit for modulating Pro biosynthesis and production in stressed plants. Considering the recent literature, this paper in its first part overviews Pro biosynthesis and transport in plants and also briefly highlights the significance of Pro in plant responses to salt and drought stress. Secondly, this paper discusses mechanisms underlying the regulation of Pro metabolism in salt and drought-exposed plant via phytohormones, mineral nutrients and transgenic approaches. The outcome of the studies may give new opportunities in modulating Pro metabolism for improving plant tolerance to salt and drought stress and benefit sustainable agriculture.

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.03.018
      Issue No: Vol. 115 (2017)
       
  • Aluminum induced physiological and proteomic responses in tea (Camellia
           sinensis) roots and leaves
    • Authors: Qingshan Xu; Yu Wang; Zhaotang Ding; Kai Fan; Dexin Ma; Yongliang Zhang; Qi Yin
      Pages: 141 - 151
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Qingshan Xu, Yu Wang, Zhaotang Ding, Kai Fan, Dexin Ma, Yongliang Zhang, Qi Yin
      Tea (Camellia sinensis (L.) O. Kuntze), is an aluminum (Al) hyperaccumulator and grows well in acid soils. Although Al-induced growth of tea plant has been studied, the proteomic profiles of tea plants in response to Al are unclear. In the present study, the proteomic profiles in tea roots and leaves under Al stress were investigated using iTRAQ proteomics approach. In total, 755 and 1059 differentially expressed proteins were identified in tea roots and leaves, respectively. KEGG enrichment analysis showed that the differentially expressed proteins in roots were mainly involved in 11 pathways whereas those from leaves were mainly involved in 9 pathways. Abundance of most protein functions in glycolytic metabolism were enhanced in tea roots, and proteins involved in photosynthesis were stimulated in tea leaves. The protein ferulate-5-hydroxylase (F5H) in lignin biosynthetic pathway was down-regulated in both roots and leaves. Furthermore, antioxidant enzymes (ascorbate peroxidase, catalase and glutathione S-transferase) and citrate synthesis were accumulated in tea roots in response to Al. The results indicated that active photosynthesis and glycolysis as well as increased activities of antioxidant enzymes can be considered as a possible reason for the stimulatory effects of Al on the growth of tea plants. Additionally, the down-regulation of F5H and the binding of Al and phenolic acids may reduce the accumulation of lignin.
      Graphical abstract image

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.03.017
      Issue No: Vol. 115 (2017)
       
  • Tissue-specific gene-expression patterns of genes associated with
           thymol/carvacrol biosynthesis in thyme (Thymus vulgaris L.) and their
           differential changes upon treatment with abiotic elicitors
    • Authors: Mohammad Majdi; Atefe Malekzadeh-Mashhady; Asad Maroufi; Christoph Crocoll
      Pages: 152 - 162
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Mohammad Majdi, Atefe Malekzadeh-Mashhady, Asad Maroufi, Christoph Crocoll
      Thyme (Thymus vulgaris L.) is known to produce a variety of phenolic monoterpenes such as thymol and carvacrol. Thymol and carvacrol are health-promoting, biocide and antitoxin compounds and have been considered as the main constituents of essential oils in T. vulgaris. To improve our understanding of the regulation of monoterpene biosynthesis in thyme, the expression of genes related to thymol and carvacrol biosynthesis in different tissues and in response to abiotic elicitors was analyzed. Methyl jasmonate (MeJA), salicylic acid (SA), trans-cinnamic acid (tCA) and UV-C irradiation were applied to T. vulgare leaves and transcript levels of early (DXR) and late (TvTPS1, CYP71D178 and CYP71D180) biosynthetic genes of thymol and carvacrol were measured. The results showed that early step and late step genes in thymol/carvacrol biosynthesis are differentially regulated. DXR was not found to be exclusively expressed in glandular trichomes; in contrast, biosynthetic genes including γ-terpinene synthase (TvTPS1) and two cytochrome P450s, CYP71D178 and CYP71D180, were preferentially expressed in glandular secretory trichomes. The high expression of late biosynthetic genes in glandular trichomes, which also contain the highest concentration of thymol and carvacrol, suggests that glandular trichomes are the structure in which thymol/carvacrol biosynthesis and accumulation occur. Our results indicate that in addition to abiotic elicitors, developmental and spatial factors also play a key role in the biosynthesis of thymol and carvacrol, most likely relating to glandular trichome density and/or activity. Hence optimization of these factors could be considered as a useful strategy to achieve high yield of valuable compounds in T. vulgare or other closely related plant species.

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.03.016
      Issue No: Vol. 115 (2017)
       
  • A protective role for nitric oxide and salicylic acid for arsenite
           phytotoxicity in rice (Oryza sativa L.)
    • Authors: Amit Pal Singh; Garima Dixit; Amit Kumar; Seema Mishra; Navin Kumar; Sameer Dixit; Pradyumna Kumar Singh; Sanjay Dwivedi; Prabodh Kumar Trivedi; Vivek Pandey; Om Prakash Dhankher; Gareth J. Norton; Debasis Chakrabarty; Rudra Deo Tripathi
      Pages: 163 - 173
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Amit Pal Singh, Garima Dixit, Amit Kumar, Seema Mishra, Navin Kumar, Sameer Dixit, Pradyumna Kumar Singh, Sanjay Dwivedi, Prabodh Kumar Trivedi, Vivek Pandey, Om Prakash Dhankher, Gareth J. Norton, Debasis Chakrabarty, Rudra Deo Tripathi
      Nitric oxide (NO) and salicylic acid (SA) are important signaling molecules in plant system. In the present study both NO and SA showed a protective role against arsenite (AsIII) stress in rice plants when supplied exogenously. The application of NO and SA alleviated the negative impact of AsIII on plant growth. Nitric oxide supplementation to AsIII treated plants greatly decreased arsenic (As) accumulation in the roots as well as shoots/roots translocation factor. Arsenite exposure in plants decreased the endogenous levels of NO and SA. Exogenous supplementation of SA not only enhanced endogenous level of SA but also the level of NO through enhanced nitrate reductase (NR) activity, whether AsIII was present or not. Exogenously supplied NO decreased the NR activity and level of endogenous NO. Arsenic accumulation was positively correlated with the expression level of OsLsi1, a transporter responsible for AsIII uptake. The endogenous level of NO and SA were positively correlated to each other either when AsIII was present or not. This close relationship indicates that NO and SA work in harmony to modulate the signaling response in AsIII stressed plants.

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.02.019
      Issue No: Vol. 115 (2017)
       
  • Changes in ABA, IAA and JA levels during calyx, fruit and leaves
           development in cape gooseberry plants (Physalis peruviana L.)
    • Authors: F. Álvarez-Flórez; C. López-Cristoffanini; O. Jáuregui; L.M. Melgarejo; M. López-Carbonell
      Pages: 174 - 182
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): F. Álvarez-Flórez, C. López-Cristoffanini, O. Jáuregui, L.M. Melgarejo, M. López-Carbonell
      Changes in abscisic acid (ABA), indole-3-acetic acid (IAA) and jasmonic acid (JA) content in developing calyx, fruits and leaves of Physalis peruviana L. plants were analysed. Plant hormones have been widely studied for their roles in the regulation of various aspects related to plant development and, in particular, into their action during development and ripening of fleshly fruits. The obtained evidences suggest that the functions of these hormones are no restricted to a particular development stage, and more than one hormone is involved in controlling various aspects of plant development. Our results will contribute to understand the role of these hormones during growth and development of calyx, fruits and leaves in cape gooseberry plants. This work offers a good, quickly and efficiently protocol to extract and quantify simultaneously ABA, IAA and JA in different tissues of cape gooseberry plants.

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.03.024
      Issue No: Vol. 115 (2017)
       
  • Effect of exogenously applied molybdenum on its absorption and nitrate
           metabolism in strawberry seedlings
    • Authors: Li Liu; Wei Xiao; Ling Li; Dong-Mei Li; Dong-Sheng Gao; Cui-ying Zhu; Xi-Ling Fu
      Pages: 200 - 211
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Li Liu, Wei Xiao, Ling Li, Dong-Mei Li, Dong-Sheng Gao, Cui-ying Zhu, Xi-Ling Fu
      Molybdenum (Mo)—an essential element of plants—is involved in nitrogen (N) metabolism. Plants tend to accumulate more nitrate and show lower nitrogen use efficiency (NUE) under Mo-deficient conditions. Improving NUE in fruits reduces the negative effect of large applications of chemical fertilizer, but the mechanisms underlying how Mo enhances NUE remain unclear. We cultivated strawberry seedlings sprayed with 0, 67.5, 135, 168.75, or 202.5 g Mo·ha−1 in a non-soil culture system. The Mo concentration in every plant tissue analyzed increased gradually as Mo application level rose. Mo application affected iron, copper, and selenium adsorption in roots. Seedlings sprayed with 135 g Mo·ha−1 had a higher [15N] shoot:root (S:R) ratio, and 15NUE, and produced higher molybdate transporter type 1 (MOT1) expression levels in the roots and leaves. Seedlings sprayed with 135 g Mo·ha−1 also had relatively high nitrogen metabolic enzyme activities and up-regulated transcript levels of nitrate uptake genes (NRT1.1; NRT2.1) and nitrate-responsive genes. Furthermore, there was a significantly lower NO3 − concentration in the leaves and roots, a higher NH4 + concentration in leaves, and a higher glutamine/glutamate (Gln/Glu) concentration at 135 g Mo·ha−1. Seedlings sprayed with 202.5 g Mo·ha−1 showed the opposite trend. Taken together, these results suggest that a 135 g Mo·ha−1 application was optimal because it enhanced NO3 − transport from the roots to the shoots and increased NUE by mediating nitrogen metabolic enzyme activities, nitrate transport, and nitrate assimilation gene activities.

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.03.015
      Issue No: Vol. 115 (2017)
       
  • First confirmation and characterization of target and non-target site
           resistance to glyphosate in Palmer amaranth (Amaranthus palmeri) from
           Mexico
    • Authors: Jose Alfredo Dominguez-Valenzuela; Javid Gherekhloo; Pablo Tomás Fernández-Moreno; Hugo Enrique Cruz-Hipolito; Ricardo Alcántara-de la Cruz; Eduardo Sánchez-González; Rafael De Prado
      Pages: 212 - 218
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Jose Alfredo Dominguez-Valenzuela, Javid Gherekhloo, Pablo Tomás Fernández-Moreno, Hugo Enrique Cruz-Hipolito, Ricardo Alcántara-de la Cruz, Eduardo Sánchez-González, Rafael De Prado
      Following the introduction of glyphosate-resistant (GR)-cotton crops in Mexico, farmers have relied upon glyphosate as being the only herbicide for in-season weed control. Continuous use of glyphosate within the same year and over multiple successive years has resulted in the selection of glyphosate resistance in Palmer amaranth (Amarantus palmeri). Dose-response assays confirmed resistance in seven different accessions. The resistance ratio based on GR50 values (50% growth reduction) varied between 12 and 83. At 1000 μM glyphosate, shikimic acid accumulation in the S-accession was 30- to 2-fold higher at compared to R-accessions. At 96 h after treatment, 35–44% and 61% of applied 14C-glyphosate was taken up by leaves of plants from R- and S-accessions, respectively. At this time, a significantly higher proportion of the glyphosate absorbed remained in the treated leaf of R-plants (55–69%) compared to S-plants (36%). Glyphosate metabolism was low and did not differ between resistant and susceptible plants. Glyphosate was differentially metabolized to AMPA and glyoxylate in plants of R- and S-accessions, although it was low in both accessions (<10%). There were differences in 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme activity by 50% (I50) between R- and S-accessions. However, no significant differences were found in the basal EPSPS activity (μmol inorganic phosphate μg−1 total soluble protein min−1) between R- and S-accessions. A point mutation Pro-106-Ser was evidenced in three accessions. The results confirmed the resistance of Palmer amaranth accessions to glyphosate collected from GR-cotton crops from Mexico. This is the first study demonstrating glyphosate-resistance in Palmer amaranth from Mexico.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.03.022
      Issue No: Vol. 115 (2017)
       
  • Overexpression of MpCYS4, a phytocystatin gene from Malus prunifolia
           (Willd.) Borkh., delays natural and stress-induced leaf senescence in
           apple
    • Authors: Yanxiao Tan; Yingli Yang; Chao Li; Bowen Liang; Mingjun Li; Fengwang Ma
      Pages: 219 - 228
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Yanxiao Tan, Yingli Yang, Chao Li, Bowen Liang, Mingjun Li, Fengwang Ma
      Phytocystatins are a well-characterized class of naturally occurring protease inhibitors that prevent the catalysis of papain-like cysteine proteases. The action of cystatins in stress tolerance has been studied intensively, but relatively little is known about their functions in plants during leaf senescence. Here, we examined the potential roles of the apple cystatin, MpCYS4, in leaf photosynthesis as well as the concentrations and composition of leaf proteins when plants encounter natural or stress-induced senescence. Overexpression of this gene in apple rootstock M26 effectively slowed the senescence-related declines in photosynthetic activity and chlorophyll concentrations and prevented the action of cysteine proteinases during the process of degrading proteins (e.g., Rubisco) in senescing leaves. Moreover, MpCYS4 alleviated the associated oxidative damage and enhanced the capacity of plants to eliminate reactive oxygen species by activating antioxidant enzymes such as ascorbate peroxidase, peroxidase, and catalase. Consequently, plant cells were protected against damage from free radicals during leaf senescence. Based on these results, we conclude that MpCYS4 functions in delaying natural and stress-induced senescence of apple leaves.

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.03.025
      Issue No: Vol. 115 (2017)
       
  • Overexpression of cotton PYL genes in Arabidopsis enhances the transgenic
           plant tolerance to drought stress
    • Authors: Yun Chen; Li Feng; Ning Wei; Zhi-Hao Liu; Shan Hu; Xue-Bao Li
      Pages: 229 - 238
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Yun Chen, Li Feng, Ning Wei, Zhi-Hao Liu, Shan Hu, Xue-Bao Li
      PYR/PYL/RCAR proteins are putative abscisic acid (ABA) receptors that play important roles in plant responses to biotic and abiotic stresses. In this study, 27 predicted PYL proteins were identified in cotton (Gossypium hirsutum). Sequence analysis showed they are conserved in structures. Phylogenetic analysis showed that cotton PYL family could be categorized into three groups. Yeast two-hybrid assay revealed that the GhPYL proteins selectively interacted with some GhPP2C proteins. Quantitative RT-PCR analysis indicated that the most of nine GhPYL genes were down-regulated, while the other three were up-regulated in cotton under drought stress. Overexpression of GhPYL10/12/26 in Arabidopsis conferred the transgenic plants increased ABA sensitivity during seed germination and early seedling growth. On the contrary, the transgenic seedlings displayed better growth status and longer primary roots under normal conditions and mannitol stress, compared with wild type. Furthermore, the transgenic plants showed the enhanced drought tolerance, relative to wild type, when they were suffered from drought stress. Expression of some stress-related genes in transgenic plants was significant higher than that in wild type under osmotic stress. Thus, our data suggested that these cotton PYL genes may be involved in plant response and defense to drought/osmotic stress.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.03.023
      Issue No: Vol. 115 (2017)
       
  • Prognosis of physiological disorders in physic nut to N, P, and K
           deficiency during initial growth
    • Authors: Elcio Ferreira Santos; Fernando Giovannetti Macedo; Bruno José Zanchim; Giuseppina Pace Pereira Lima; José Lavres
      Pages: 249 - 258
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Elcio Ferreira Santos, Fernando Giovannetti Macedo, Bruno José Zanchim, Giuseppina Pace Pereira Lima, José Lavres
      The description of physiological disorders in physic nut plants deficient in nitrogen (N), phosphorus (P) and potassium (K) may help to predict nutritional imbalances before the appearance of visual symptoms and to guide strategies for early nutrient supply. The aim of this study was to evaluate the growth of physic nuts (Jatropha curcas L.) during initial development by analyzing the gas exchange parameters, nutrient uptake and use efficiency, as well as the nitrate reductase and acid phosphatase activities and polyamine content. Plants were grown in a complete nutrient solution and solutions from which N, P or K was omitted. The nitrate reductase activity, phosphatase acid activity, polyamine content and gas exchange parameters from leaves of N, P and K-deficient plants indicates earlier imbalances before the appearance of visual symptoms. Nutrient deficiencies resulted in reduced plant growth, although P- and K-deficient plants retained normal net photosynthesis (A), stomatal conductance (g s ) and instantaneous carboxylation efficiency (k) during the first evaluation periods, as modulated by the P and K use efficiencies. Increased phosphatase acid activity in P-deficient plants may also contribute to the P use efficiency and to A and gs during the first evaluations. Early physiological and biochemical evaluations of N-, P- and K-starved plants may rely on reliable, useful methods to predict early nutritional imbalances.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.001
      Issue No: Vol. 115 (2017)
       
  • Changes in growth and physiological parameters of spring barley and common
           radish under the influence of 1-butyl-2,3-dimethylimidazolium
           tetrafluoroborate
    • Authors: Robert Biczak
      Pages: 259 - 268
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Robert Biczak
      Ionic liquids (ILs) constitute a large group of chemical substances, which, thanks to their desirable properties, still attract attention of scientists and representatives of the industry. This may lead to a greater commercial use of these compounds, which will undoubtedly lead to the contamination of soils, constituting the basis of plant vegetation, with these substances. This paper presents effect of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BMMIM][BF4] on the growth and development of spring barley and common radish and on the physiological and biochemical changes in these plants. The used IL was characterized by relatively high toxicity for the monocotyledonous plant, which was exhibited by shortening of the plant length and their root length, decreasing the fresh weight yield. Moreover, [BMMIM][BF4] led to the decrease in the content of all photosynthetic pigments in spring barley seedlings, reflecting the decrease in the fresh yield. Furthermore, the increase of malondialdehyde (MDA) level and changes in contents of hydrogen peroxide (H2O2) and the activity of antioxidant enzymes, that is, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) may suggest the occurrence of oxidative stress in spring barley. The decrease in the content of photosynthetic pigment and the increase of POD activity constitute the most reliable markers of oxidative stress and, at the same time, the signs of early aging of spring barley plants. Common radish was the plant with a very high tolerance for the used IL, which can be indicated by, that is, EC50 values, determined based on inhibition of root length, plant length, and fresh weight yield.
      Graphical abstract image

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.002
      Issue No: Vol. 115 (2017)
       
  • Physiological investigation of
           C4-phosphoenolpyruvate-carboxylase-introduced rice line shows that sucrose
           metabolism is involved in the improved drought tolerance
    • Authors: Chen Zhang; Xia Li; Yafei He; Jinfei Zhang; Ting Yan; Xiaolong Liu
      Pages: 328 - 342
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Chen Zhang, Xia Li, Yafei He, Jinfei Zhang, Ting Yan, Xiaolong Liu
      We compared the drought tolerance of wild-type (WT) and transgenic rice plants (PC) over-expressing the maize C4 PEPC gene, which encodes phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) gene, and evaluated the roles of saccharide and sugar-related enzymes in the drought response. Pot-grown seedlings were subjected to real drought conditions outdoors, and the yield components were compared between PC and untransformed wild-type (WT) plants. The stable yield from PC plants was associated with higher net photosynthetic rate under the real drought treatment. The physiological characters of WT and PC seedlings under a simulated drought treatment (25% (w/v) polyethylene glycol-6000 for 3 h; PEG 6000 treatment) were analyzed in detail for the early response of drought. The relative water content was higher in PC than in WT, and PEPC activity and the C 4 -PEPC transcript level in PC were elevated under the simulated drought conditions. The endogenous saccharide responses also differed between PC and WT under simulated drought stress. The higher sugar decomposition rate in PC than in WT under drought analog stress was related to the increased activities of sucrose phosphate synthase, sucrose synthase, acid invertase, and neutral invertase, increased transcript levels of VIN1, CIN1, NIN1, SUT2, SUT4, and SUT5, and increased activities of superoxide dismutase and peroxidase in the leaves. The greater antioxidant defense capacity of PC and its relationship with saccharide metabolism was one of the reasons for the improved drought tolerance. In conclusion, PEPC effectively alleviated oxidative damage and enhanced the drought tolerance in rice plants, which were more related to the increase of the endogenous saccharide decomposition. These findings show that components of C4 photosynthesis can be used to increase the yield of rice under drought conditions.

      PubDate: 2017-04-19T21:15:13Z
      DOI: 10.1016/j.plaphy.2017.03.019
      Issue No: Vol. 115 (2017)
       
  • Genome-wide identification and analysis of the Populus trichocarpa TIFY
           gene family
    • Authors: Yue Wang; Feng Pan; Danmei Chen; Wenyuan Chu; Huanlong Liu; Yan Xiang
      Pages: 360 - 371
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Yue Wang, Feng Pan, Danmei Chen, Wenyuan Chu, Huanlong Liu, Yan Xiang
      The plant-specific TIFY proteins are widely present in land plants and play the important roles in the regulation of plant stress-responses. In this study, we carried out a bioinformatics analysis of TIFY genes in Populus trichocarpa by determining the phylogenetic relationship, chromosomal location and gene structure and expression profiles analysis under stresses. The 24 TIFY genes were identified and classified into four subfamilies (ZML, JAZ, PPD and TIFY). The 24 TIFY genes were irregularly located on 13 of the 19 chromosomes; ten gene pairs were involved in large-scale interchromosomal segmental duplication events; we identified 17 collinear TIFY gene pairs in the Populus trichocarpa genome. Numerous abiotic stress cis-elements were widely found in the promoter regions. Analysis of the Ka/Ks ratios indicated that the paralogs of the PtTIFY family principally underwent purifying selection. Microarray data and qRT-PCR analysis revealed that 24 PtTIFY genes were differentially expressed in various tissues. Quantitative real-time RT-PCR analysis of TIFY genes expression in response to salt, JA hormones and low-temperature stress revealed their stress-responses profiles. The results of this study provided valuable information for further exploration of the TIFY gene family in Populus trichocarpa.

      PubDate: 2017-04-19T21:15:13Z
      DOI: 10.1016/j.plaphy.2017.04.015
      Issue No: Vol. 115 (2017)
       
  • Effect of short-term Zn/Pb or long-term multi-metal stress on
           physiological and morphological parameters of metallicolous and
           nonmetallicolous Echium vulgare L. populations
    • Authors: Sławomir Dresler; Magdalena Wójciak-Kosior; Ireneusz Sowa; Grzegorz Stanisławski; Izabela Bany; Małgorzata Wójcik
      Pages: 380 - 389
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Sławomir Dresler, Magdalena Wójciak-Kosior, Ireneusz Sowa, Grzegorz Stanisławski, Izabela Bany, Małgorzata Wójcik
      The aim of the study was to determine the response of metallicolous and nonmetallicolous Echium vulgare L. populations to chronic multi-metal (Zn, Pb, Cd) and acute Zn (200, 400 μM) and Pb (30, 60 μM) stress. Three populations of E. vulgare, one from uncontaminated and two from metal-contaminated areas, were studied. Two types of experiments were performed – a short-term hydroponic experiment with acute Zn or Pb stress and a long-term manipulative soil experiment with the use of soils from the sites of origin of the three populations. Growth parameters, such as shoot and root fresh weight and leaf area, as well as organic acid accumulation were determined. Moreover, the concentration of selected secondary metabolites and antioxidant capacity in the three populations exposed to Pb or Zn excess were measured. Both metallicolous populations generally achieved higher biomass compared with the nonmetallicolous population cultivated under metal stress in hydroponics or on metalliferous substrates. Plants exposed to Pb or Zn excess or contaminated soil substrate exhibited higher malate and citrate concentrations compared with the reference (no metal stress) plants. It was observed that Zn or Pb stress increased accumulation of allantoin, chlorogenic and rosmarinic acids, total phenolics, and flavonoids. Moreover, it was shown that Pb sequestration in the roots or Zn translocation to the shoots may play a role in enhanced metal tolerance of metallicolous populations under acute Pb/Zn stress.
      Graphical abstract image

      PubDate: 2017-04-19T21:15:13Z
      DOI: 10.1016/j.plaphy.2017.04.016
      Issue No: Vol. 115 (2017)
       
  • Cadmium hampers salt tolerance of Sesuvium portulacastrum
    • Authors: Mariem Wali; Soledad Martos; Laura Pérez-Martín; Chedly Abdelly; Tahar Ghnaya; Charlotte Poschenrieder; Benet Gunsé
      Pages: 390 - 399
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Mariem Wali, Soledad Martos, Laura Pérez-Martín, Chedly Abdelly, Tahar Ghnaya, Charlotte Poschenrieder, Benet Gunsé
      It is well known that salinity reduces cadmium toxicity in halophytes. However, the possible interference of Cd with the mechanisms of salt tolerance is poorly explored. The aim of this study was to see whether Cd affects salt tolerance mechanisms in the halophyte Sesuvium portulacastrum. S. portulacastrum plants obtained from cuttings were grown in hydroponics for 3 weeks and then exposed to low (0.09 mM) or moderate (200 mM) NaCl concentrations, alone or in combination with 25 μM CdCl2. Microscopy observation revealed two strategies of salt tolerance: euhalophytism and secretion of salt by bladder cells. Cadmium exposure hardly influenced the total leaf Na+ concentrations. However, Cd supply delayed the salt–induced upregulation of AHA1 (plasma membrane H+-ATPase 1) and SOS1 (plasma membrane Na+ transporter “Salt Overly Sensitive 1”), genes that are essential for salt tolerance. Moreover, Cd induced the activation of BADH, coding for betaine aldehyde dehydrogenase, indicating enhanced osmotic stress due to Cd. Sodium-green fluorescence in protoplasts from plants grown with low or high NaCl, alone or in combination with Cd, revealed higher Na+ concentrations in the cytoplasm of Cd-exposed plants. Taken together the results indicate interference of Cd with salt tolerance mechanisms in S. portulacastrum. This may have consequences for the efficient use of halophytes in phytoremediation of Cd-contaminated saline soils.
      Graphical abstract image

      PubDate: 2017-04-19T21:15:13Z
      DOI: 10.1016/j.plaphy.2017.04.014
      Issue No: Vol. 115 (2017)
       
  • Impact of endophytic colonization patterns on Zamioculcas zamiifolia
           stress response and in regulating ROS, tryptophan and IAA levels under
           airborne formaldehyde and formaldehyde-contaminated soil conditions
    • Authors: Gholamreza Khaksar; Chairat Treesubsuntorn; Paitip Thiravetyan
      Pages: 1 - 9
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Gholamreza Khaksar, Chairat Treesubsuntorn, Paitip Thiravetyan
      Deeper understanding of plant-endophyte interactions under abiotic stress would provide new insights into phytoprotection and phytoremediation enhancement. Many studies have investigated the positive role of plant-endophyte interactions in providing protection to the plant against pollutant stress through auxin (indole-3-acetic acid (IAA)) production. However, little is known about the impact of endophytic colonization patterns on plant stress response in relation to reactive oxygen species (ROS) and IAA levels. Moreover, the possible effect of pollutant phase on plant stress response is poorly understood. Here, we elucidated the impact of endophytic colonization patterns on plant stress response under airborne formaldehyde compared to formaldehyde-contaminated soil. ROS, tryptophan and IAA levels in the roots and shoots of endophyte-inoculated and non-inoculated plants in the presence and absence of formaldehyde were measured. Strain-specific quantitative polymerase chain reaction (qPCR) was used to investigate dynamics of endophyte colonization. Under the initial exposure to airborne formaldehyde, non-inoculated plants accumulated more tryptophan in the shoots (compared to the roots) to synthesize IAA. However, endophyte-inoculated plants behaved differently as they synthesized and accumulated more tryptophan in the roots and, hence, higher levels of IAA accumulation and exudation within roots which might act as a signaling molecule to selectively recruit B. cereus ERBP. Under continuous airborne formaldehyde stress, higher levels of ROS accumulation in the shoots pushed the plant to synthesize more tryptophan and IAA in the shoots (compared to the roots). Higher levels of IAA in the shoots might act as the potent driving force to relocalize B. cereus ERBP from roots to the shoots. In contrast, under formaldehyde-contaminated soil, B. cereus ERBP colonized root tissues without moving to the shoots since there was a sharp increase in ROS, tryptophan and IAA levels of the roots without any significant increase in the shoots. Pollutant phase affected endophytic colonization patterns and plant stress responses differently.
      Graphical abstract image

      PubDate: 2017-03-04T09:07:29Z
      DOI: 10.1016/j.plaphy.2017.02.016
      Issue No: Vol. 114 (2017)
       
  • The wheat mutant DELLA-encoding gene (Rht-B1c) affects plant
           photosynthetic responses to cadmium stress
    • Authors: Anelia G. Dobrikova; Ekaterina K. Yotsova; Andreas Börner; Svetlana P. Landjeva; Emilia L. Apostolova
      Pages: 10 - 18
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Anelia G. Dobrikova, Ekaterina K. Yotsova, Andreas Börner, Svetlana P. Landjeva, Emilia L. Apostolova
      Тhe sensitivity to cadmium (Cd) stress of two near-isogenic wheat lines with differences at the Rht-B1 locus, Rht-B1a (tall wild type, encoding DELLA proteins) and Rht-B1c (dwarf mutant, encoding modified DELLA proteins), was investigated. The effects of 100 μM CdCl2 on plant growth, pigment content and functional activity of the photosynthetic apparatus of wheat seedlings grown on a nutrient solution were evaluated through a combination of PAM chlorophyll fluorescence, oxygen evolution, oxidation-reduction kinetics of P700 and 77 K fluorescence. The results showed that the wheat mutant (Rht-B1c) was more tolerant to Cd stress compared to the wild type (Rht-B1a), as evidenced by the lower reductions in plant growth and pigment content, lower inhibition of photosystem I (PSI) and photosystem II (PSII) photochemistry and of the oxygen evolution measured with Clark-type and Joliot-type electrodes. Furthermore, the enhanced Cd tolerance was accompanied by increased Cd accumulation within mutant plant tissues. The molecular mechanisms through which the Rht-B1c mutation improves plant tolerance to Cd stress involve structural alterations in the mutant photosynthetic membranes leading to better protection of the Mn cluster of oxygen-evolving complex and increased capacity for PSI cyclic electron transport, protecting photochemical activity of the photosynthetic apparatus under stress. This study suggests a role for the Rht-B1c-encoded DELLA proteins in protective mechanisms and tolerance of the photosynthetic apparatus in wheat plants exposed to heavy metals stress.
      Graphical abstract image

      PubDate: 2017-03-04T09:07:29Z
      DOI: 10.1016/j.plaphy.2017.02.015
      Issue No: Vol. 114 (2017)
       
  • Comparative study of withanolide production and the related
           transcriptional responses of biosynthetic genes in fungi elicited cell
           suspension culture of Withania somnifera in shake flask and bioreactor
    • Authors: Seema Ahlawat; Parul Saxena; Athar Ali; Shazia Khan; Malik Z. Abdin
      Pages: 19 - 28
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Seema Ahlawat, Parul Saxena, Athar Ali, Shazia Khan, Malik Z. Abdin
      Ashwagandha (Withania somnifera) is one of the most reputed medicinal plants in the traditional medicinal system. In this study, cell suspension culture of W. somnifera was elicited with cell homogenates of fungi (A. alternata, F. solani, V. dahliae and P. indica) in shake flask and the major withanolides like withanolide A, withaferin A and withanone were analysed. Simultaneously expression levels of key pathway genes from withanolides biosynthetic pathways were also checked via quantitative PCR in shake flask as well as in bioreactor. The results show that highest gene expression of 10.8, 5.8, 4.9, and 3.3 folds were observed with HMGR among all the expressed genes in cell suspension cultures with cell homogenates of 3% P. indica, 5% V. dahliae, 3% A. alternata and 3% F. solani, respectively, in comparison to the control in shake flask. Optimized concentration of cell homogenate of P. indica (3% v/v) was added to the growing culture in 5.0-l bioreactor under optimized up-scaling conditions and harvested after 22 days. The genes of MVA, MEP and withanolides biosynthetic pathways like HMGR, SS, SE, CAS, FPPS, DXR and DXS were up-regulated by 12.5, 4.9, 2.18, 4.65, 2.34, 1.89 and 1.4 folds, respectively in bioreactor. The enhancement of biomass (1.13 fold) and withanolides [withanolide A (1.7), withaferin A (1.5), and withanone (1.5) folds] in bioreactor in comparison to shake flask was also found to be in line with the up-regulation of genes of withanolide biosynthetic pathways.

      PubDate: 2017-03-04T09:07:29Z
      DOI: 10.1016/j.plaphy.2017.02.013
      Issue No: Vol. 114 (2017)
       
  • Cadmium-induced changes in vacuolar aspects of Arabidopsis thaliana
    • Authors: Shanti S. Sharma; Kotaro Yamamoto; Kohei Hamaji; Miwa Ohnishi; Aya Anegawa; Shashi Sharma; Sveta Thakur; Vijay Kumar; Tomohiro Uemura; Akihiko Nakano; Tetsuro Mimura
      Pages: 29 - 37
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Shanti S. Sharma, Kotaro Yamamoto, Kohei Hamaji, Miwa Ohnishi, Aya Anegawa, Shashi Sharma, Sveta Thakur, Vijay Kumar, Tomohiro Uemura, Akihiko Nakano, Tetsuro Mimura
      We have examined the changes due to Cd treatment in the vacuolar form in root tip cortical cells in Arabidopsis thaliana employing a transformant with GFP fused to a tonoplast protein. A Cd-induced enhancement in complexity with general expansion of vacuolar system within 24 h was evident. The changes in the vacuolar form were dependent on the applied Cd concentrations. Concomitantly, as revealed through dithizone staining, Cd accumulated in the seedling roots exhibiting abundance of Cd-dithizone complexes in root tip, root hairs and vasculature. To get insight into the involvement of SNARE protein-mediated vesicle fusion in Cd detoxification, the magnitude of Cd toxicity in a couple of knock out mutants of the vacuolar Qa-SNARE protein VAM3/SYP22 was compared with that in the wild type. The Cd toxicity appeared to be comparable in the mutants and the wild type. In order to analyze the Cd effects at cellular level, we treated the Arabidopsis suspension-cultured cells with Cd. Cd, however, did not induce a change in the vacuolar form in suspension-cultured cells although Cd measured with ICP-MS was obviously taken up into the cell. The V-ATPase activity in the microsomal fractions from vacuoles isolated from A. thaliana suspension cultured cells remained unaffected by Cd. Changes in the levels of certain metabolites of Cd-treated cells were also not so distinct except for those of glutathione. The significance of findings is discussed.

      PubDate: 2017-03-04T09:07:29Z
      DOI: 10.1016/j.plaphy.2017.02.017
      Issue No: Vol. 114 (2017)
       
  • Effects of cadmium-resistant fungi Aspergillus aculeatus on metabolic
           profiles of bermudagrass [Cynodondactylon (L.)Pers.] under Cd stress
    • Authors: Xiaoning Li; Margaret Mukami Gitau; Shijuan Han; Jinmin Fu; Yan Xie
      Pages: 38 - 50
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Xiaoning Li, Margaret Mukami Gitau, Shijuan Han, Jinmin Fu, Yan Xie
      Plants' tolerance to heavy metal stress may be induced by the exploitation of microbes. The objectives of this study were to investigate the effect of cadmium (Cd)-resistant fungus, Aspergillus aculeatus, on tolerance to Cd and alteration of metabolites in bermudagrass under Cd stress, and identify the predominant metabolites associated with Cd tolerance. Two genotypes of bermudagrass with contrasting Cd tolerance (Cd-sensitive ‘WB92’ and Cd-tolerant ‘WB242’) were exposed to 0, 50, 150 and 250 mg kg−1 Cd for 21 days. Physiological responses of bermudagrass to Cd stress were evaluated based on the relative growth rate (RGR) and normalized relative transpiration rate (NRT). Plants inoculated with A. aculeatus exhibited higher RGR and NRT under Cd stress than those of non-inoculated plants, regardless of genotypes. A total of 32 Cd-responsive metabolites in leaves and 21 in roots were identified in the two genotypes, including organic acids, amino acids, sugars, and fatty acids and others. Interestingly, under Cd stress, the leaves of inoculated ‘WB92’ accumulated less citric acid, aspartic acid, glutamic acid, sucrose, galactose, but more sorbose and glucose, while inoculated ‘WB242’ leaves had less citric acid, malic acid, sucrose, sorbose, but more fructose and glucose, compared to non-inoculated plants. In ‘WB92’ roots, the A. aculeatus reduced mannose content, but increased trehalose and citric acid content, while in ‘WB242’, it decreased sucrose, but enhanced citric acid content, compared to Cd regime. The results of this study suggest that A. aculeatus may induce accumulation of different metabolites associated with Cd tolerance in bermudagrass.

      PubDate: 2017-03-21T19:17:30Z
      DOI: 10.1016/j.plaphy.2017.02.014
      Issue No: Vol. 114 (2017)
       
  • Antioxidant defense during desiccation of the resurrection plant Haberlea
           rhodopensis
    • Authors: Katya Georgieva; Soleya Dagnon; Emiliya Gesheva; Dimitar Bojilov; Gergana Mihailova; Snezhana Doncheva
      Pages: 51 - 59
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Katya Georgieva, Soleya Dagnon, Emiliya Gesheva, Dimitar Bojilov, Gergana Mihailova, Snezhana Doncheva
      Maintaining a strong antioxidant system is essential for preventing drought-induced oxidative stress. Thus, in the present study we investigated the role of some non-enzymic and enzymic antioxidants in desiccation tolerance of Haberlea rhodopensis. The effects of high light upon desiccation on antioxidant capacity was estimated by comparing the response of shade and sun plants. The significant enhancement of the antioxidant capacity at 8% RWC corresponded to an enormous increase in flavonoid content. The important role of ascorbate-glutathione cycle in overcoming oxidative stress during drying of H. rhodopensis was established. The antioxidant capacity increased upon dehydration of both shade and sun plants but some differences in non-enzymatic and enzymatic antioxidants were observed. Investigations on the role of polyphenols in desiccation tolerance are scarce. In the present study the polyphenol profiles (fingerprints) of the resurrection plant Haberlea rhodopensis, including all components of the complex are obtained for the first time. It was clarified that the polyphenol complex of H. rhodopensis includes only two types of glycosides - phenylethanoid glucosides and hispidulin 8-C-glucosides. Upon desiccation the polyphenol content increase and the main role of phenylethanoid glucosides in the protection of H. rhodopensis was revealed.

      PubDate: 2017-03-21T19:17:30Z
      DOI: 10.1016/j.plaphy.2017.02.021
      Issue No: Vol. 114 (2017)
       
  • A Glycine max homolog of NON-RACE SPECIFIC DISEASE RESISTANCE 1 (NDR1)
           alters defense gene expression while functioning during a resistance
           response to different root pathogens in different genetic backgrounds
    • Authors: Brant T. McNeece; Shankar R. Pant; Keshav Sharma; Prakash Niruala; Gary W. Lawrence; Vincent P. Klink
      Pages: 60 - 71
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Brant T. McNeece, Shankar R. Pant, Keshav Sharma, Prakash Niruala, Gary W. Lawrence, Vincent P. Klink
      A Glycine max homolog of the Arabidopsis thaliana NON-RACE SPECIFIC DISEASE RESISTANCE 1 (NDR1) coiled-coil nucleotide binding leucine rich repeat (CC-NB-LRR) defense signaling gene (Gm-NDR1-1) is expressed in root cells undergoing a defense response to the root pathogenic nematode, Heterodera glycines. Gm-NDR1-1 overexpression in the H. glycines-susceptible genotype G. max [Williams 82/PI 518671] impairs parasitism. In contrast, Gm-NDR1-1 RNA interference (RNAi) in the H. glycines-resistant genotype G. max [Peking/PI 548402] facilitates parasitism. The broad effectiveness of Gm-NDR1-1 in impairing parasitism has then been examined by engineering its heterologous expression in Gossypium hirsutum which is susceptible to the root pathogenic nematode Meloidogyne incognita. The heterologous expression of Gm-NDR1-1 in G. hirsutum effectively impairs M. incognita parasitism, reducing gall, egg mass, egg and juvenile numbers. In contrast to our prior experiments examining the effectiveness of the heterologous expression of a G. max homolog of the A. thaliana salicyclic acid signaling (SA) gene NONEXPRESSOR OF PR1 (Gm-NPR1-2), no cumulative negative effect on M. incognita parasitism has been observed in G. hirsutum expressing Gm-NDR1-1. The results indicate a common genetic basis exists for plant resistance to parasitic nematodes that involves Gm-NDR1. However, the Gm-NDR1-1 functions in ways that are measurably dissimilar to Gm-NPR1-2. Notably, Gm-NDR1-1 overexpression leads to increased relative transcript levels of its homologs of A. thaliana genes functioning in SA signaling, including NPR1-2, TGA2-1 and LESION SIMULATING DISEASE1 (LSD1-2) that is lost in Gm-NDR1-1 RNAi lines. Similar observations have been made regarding the expression of other defense genes.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.02.022
      Issue No: Vol. 114 (2017)
       
  • Changes in the mitochondrial protein profile due to ROS eruption during
           ageing of elm (Ulmus pumila L.) seeds
    • Authors: Ying Li; Yu Wang; Hua Xue; Hugh W. Pritchard; Xiaofeng Wang
      Pages: 72 - 87
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Ying Li, Yu Wang, Hua Xue, Hugh W. Pritchard, Xiaofeng Wang
      Reactive oxygen species (ROS)-related mitochondrial dysfunction is considered to play a vital role in seed deterioration. However, the detailed mechanisms remain largely unknown. To address this, a comparison of mitochondrial proteomes was performed, and we identified several proteins that changed in abundance with accompanying ROS eruption and mitochondrial aggregation and diffusion. These are involved in mitochondrial metabolisms, stress resistance, maintenance of structure and intracellular transport during seed aging. Reduction of ROS content by the mitochondrial-specific scavenger MitoTEMPO suppressed these changes, whereas pre-treatment of seeds with methyl viologen (MV) had the opposite effect. Furthermore, voltage-dependent anion channels (VDAC) were found to increase both in abundance and carbonylation level, accompanied by increased cytochrome c (cyt c) release from mitochondria to cytosol, indicating the profound effect of ROS and VDAC on mitochondria-dependent cell death. Carbonylation detection revealed the specific target proteins of oxidative modification in mitochondria during ageing. Notably, membrane proteins accounted for a large proportion of these targets. An in vitro assay demonstrated that the oxidative modification was concomitant with a change of VDAC function and a loss of activity in malate dehydrogenase. Our data suggested that ROS eruption induced alteration and modification of specific mitochondrial proteins that may be involved in the process of mitochondrial deterioration, which eventually led to loss of seed viability.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.02.023
      Issue No: Vol. 114 (2017)
       
  • Phosphite shifts physiological and hormonal profile of Monterey pine and
           delays Fusarium circinatum progression
    • Authors: Andreia Cerqueira; Artur Alves; Helder Berenguer; Barbara Correia; Aurelio Gómez-Cadenas; Julio Javier Diez; Pedro Monteiro; Glória Pinto
      Pages: 88 - 99
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Andreia Cerqueira, Artur Alves, Helder Berenguer, Barbara Correia, Aurelio Gómez-Cadenas, Julio Javier Diez, Pedro Monteiro, Glória Pinto
      Fusarium circinatum is the causal agent of pitch canker disease affecting Pinus spp. and Pseudotsuga menziesii worldwide. Under strict quarantine measures, alternative approaches for disease control are necessary. Phosphite (Phi) salts are known for their fungicidal activity and as plant resistance elicitors; however, its potential is yet to be acknowledged in the Pinus-F. circinatum model. The main aim of this study was to assess whether the application of a Phi-based commercial formulation would delay the progression of the pitch canker on Pinus radiata plants, and on the in vitro fungal growth. In vitro assays were performed using different Phi concentrations (1% and 4%) and a non-treated control (0%), and repeated in vivo using inoculated and non-inoculated plants. Plant physiological parameters and hormonal content were evaluated. Phi was effective at inhibiting in vitro mycelial growth in a dose dependent manner. Regardless of fungal inoculation, Phi application induced positive effects on plant performance, despite phytotoxic effects found at 4%. Fusarium circinatum infection led to a reduction in gas exchange and chlorophyll fluorescence (Fv/Fm and φPSII), while proline and hormone (JA, ABA and SA) levels increased. Phi was effective in delaying disease symptom development in a dose dependent manner, concurrent with in vitro observations: gas exchange and chlorophyll fluorescence (Fv/Fm) were unaffected; proline, MDA and ABA decreased; electrolyte leakage and total soluble sugars increased. This suggests a direct (pathogen growth inhibition) and indirect (host defense priming) action of Phi, showing that Phi represents a potential strategy to control F. circinatum infection.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.02.020
      Issue No: Vol. 114 (2017)
       
  • A salt-stress-regulator from the Poplar R2R3 MYB family integrates the
           regulation of lateral root emergence and ABA signaling to mediate salt
           stress tolerance in Arabidopsis
    • Authors: Qing Fang; Tianzhi Jiang; Liangxiang Xu; Hai Liu; Hui Mao; Xianqiang Wang; Bo Jiao; Yanjiao Duan; Qiong Wang; Qiannan Dong; Li Yang; Guozheng Tian; Chi Zhang; Yifeng Zhou; Xiaopeng Liu; Haiyang Wang; Di Fan; Bangjun Wang; Keming Luo
      Pages: 100 - 110
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Qing Fang, Tianzhi Jiang, Liangxiang Xu, Hai Liu, Hui Mao, Xianqiang Wang, Bo Jiao, Yanjiao Duan, Qiong Wang, Qiannan Dong, Li Yang, Guozheng Tian, Chi Zhang, Yifeng Zhou, Xiaopeng Liu, Haiyang Wang, Di Fan, Bangjun Wang, Keming Luo
      The roles of most MYB transcription factors (TFs) in the poplar remain unclear. Here, we demonstrate that PtrSSR1, a salt-stress-regulator in the Populus trichocarpa R2R3 MYB gene family, mediates the tolerance of transgenic Arabidopsis plants to salt stress. The transcripts of PtrSSR1 could be induced by salt stress rapidly in poplar. Subcellular localization and yeast assays indicated that PtrSSR1 encoded a nuclear protein with transactivation activity. The Arabidopsis transformants overexpressing PtrSSR1 clearly displayed lateral root emergence (LRE) inhibition compared with wild-type (Wt) under normal conditions; while upon NaCl treatment, the transformants showed improved tolerance, and the LRs emerged faster from salt-induced inhibition. A strong correlation could exist between the LRE mediated by PtrSSR1 and abscisic acid (ABA), mainly because the transformants displayed more sensitivity to exogenous ABA during both seed germination and LRE, and had a distinctly increased level of endogenous ABA. Furthermore, several ABA- and salt-related genes, such as NCED3, ABI1 and CBL1, were up-regulated. Thus, our results suggest that elevation in the endogenous ABA content bring alteration of plant LR development, and that the poplar R2R3 MYB TF PtrSSR1 vitally improve salt stress tolerance by integrating the regulation of LRE and ABA signaling in Arabidopsis.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.02.018
      Issue No: Vol. 114 (2017)
       
  • Silencing of the FRO1 gene and its effects on iron partition in Nicotiana
           benthamiana
    • Authors: Florinda Gama; Teresa Saavedra; Susana Dandlen; Amarilis de Varennes; Pedro J. Correia; Maribela Pestana; Gustavo Nolasco
      Pages: 111 - 118
      Abstract: Publication date: May 2017
      Source:Plant Physiology and Biochemistry, Volume 114
      Author(s): Florinda Gama, Teresa Saavedra, Susana Dandlen, Amarilis de Varennes, Pedro J. Correia, Maribela Pestana, Gustavo Nolasco
      To evaluate the dynamic role of the ferric-chelate reductase enzyme (FCR) and to identify possible pathways of regulation of its activity in different plant organs an investigation was conducted by virus-induced gene silencing (VIGS) using tobacco rattle virus (TRV) to silence the ferric reductase oxidase gene (FRO1) that encodes the FCR enzyme. Half of Nicotiana benthamiana plants received the VIGS vector and the rest remained as control. Four treatments were imposed: two levels of Fe in the nutrient solution (0 or 2.5 μM of Fe), each one with silenced or non-silenced (VIGS-0; VIGS-2.5) plants. Plants grown without iron (0; VIGS-0) developed typical symptoms of iron deficiency in the youngest leaves. To prove that FRO1 silencing had occurred, resupply of Fe (R) was done by adding 2.5 μM of Fe to the nutrient solution in a subset of chlorotic plants (0-R; VIGS-R). Twelve days after resupply, 0-R plants had recovered from Fe deficiency while plants containing the VIGS vector (VIGS-R) remained chlorotic and both FRO1 gene expression and FCR activity were considerably reduced, consequently preventing Fe uptake. With the VIGS technique we were able to silence the FRO1 gene in N. benthamiana and point out its importance in chlorophyll synthesis and Fe partition.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.03.004
      Issue No: Vol. 114 (2017)
       
  • Evidence towards the involvement of nitric oxide in drought tolerance of
           sugarcane
    • Authors: Neidiquele M. Silveira; John T. Hancock; Lucas Frungillo; Eleni Siasou; Fernanda C.C. Marcos; Ione Salgado; Eduardo C. Machado; Rafael V. Ribeiro
      Abstract: Publication date: Available online 8 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Neidiquele M. Silveira, John T. Hancock, Lucas Frungillo, Eleni Siasou, Fernanda C.C. Marcos, Ione Salgado, Eduardo C. Machado, Rafael V. Ribeiro
      Exogenous supplying of nitric oxide (NO) increases drought tolerance in sugarcane plants. However, little is known about the role of NO produced by plants under water deficit. The aim of this study was to test the hypothesis that drought-tolerance in sugarcane is associated with NO production and metabolism, with the more drought-tolerant genotype presenting higher NO accumulation in plant tissues. The sugarcane genotypes IACSP95-5000 (drought-tolerant) and IACSP97-7065 (drought-sensitive) were submitted to water deficit by adding polyethylene glycol (PEG-8000) in nutrient solution to reduce the osmotic potential to -0.4 MPa. For evaluating short-time responses to water deficit, leaf and root samples were taken after 24 h under water deficit. The drought-tolerant genotype presented higher root extracellular NO content, which was accompanied by higher root nitrate reductase (NR) activity as compared to the drought-sensitive genotype under water deficit. In addition, the drought-tolerant genotype had higher leaf intracellular NO content than the drought-sensitive one. IACSP95-5000 exhibited decreases in root S-nitrosoglutathione reductase (GSNOR) activity under water deficit, suggesting that S-nitrosoglutathione (GSNO) is less degraded and that the drought-tolerant genotype has a higher natural reservoir of NO than the drought-sensitive one. Those differences in intracellular and extracellular NO contents and enzymatic activities were associated with higher leaf hydration in the drought-tolerant genotype as compared to the sensitive one under water deficit.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.011
       
  • Seed dormancy and germination of the medicinal holoparasitic plant
           Cistanche deserticola from the cold desert of northwest China
    • Authors: Jia Wang; Jerry M. Baskin; Carol C. Baskin; Guofang Liu; Xuejun Yang; Zhenying Huang
      Abstract: Publication date: Available online 8 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Jia Wang, Jerry M. Baskin, Carol C. Baskin, Guofang Liu, Xuejun Yang, Zhenying Huang
      Cistanche deserticola is a holoparasitic plant with high medicinal value that reproduces only by seeds. However, the requirements for seed dormancy break and germination of this species remain unclear. The freshly matured dust-like seeds consist of a water-permeable seed coat and an undifferentiated oval-shaped embryo embedded in endosperm. No fresh seeds germinated in water or a 10−5 M fluridone solution at any incubation temperature within 60 days. Length of embryos in seeds incubated in warm- and cold-started stratification sequences had increased 10.4 and 11.7% after 50 and 40 weeks, respectively. After 6 months, length of embryos in seeds stratified at 5 °C had increased by 12%. Germination of fresh seeds and of seeds stratified at 5 °C for 6 months and then incubated in mixed fluridone/gibberellic acid 3 (GA3) solutions at 30/20 °C germinated to only 2.6 and 11.7%, respectively. Embryos of fresh seeds and of cold-stratified seeds had increased 29.4 and 15.8% in length, respectively, at the time of germination, but they never differentiated into organs. The highest germination (54.4%) was for seeds incubated in a 10−5 M solution of fluridone in darkness in spring that had overwinter on the soil surface in the natural habitat. Our study indicates that breaking of physiological dormancy (PD) occurs first and then the embryo grows to a critical length (0.44 mm) without differentiation into organs prior to seed germination. Seeds for which PD had been broken were induced to germinate by fluridone and GA3 at high temperature. Taken together, these results suggest that C. deserticola seeds have a specialized kind of morphophysiological dormancy. This study reveals possible ways to release seed dormancy that will be useful in propagating this medicinal species.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.010
       
  • Elevated CO2 and salinity are responsible for phenolics-enrichment in two
           differently pigmented lettuces
    • Authors: Cristina Sgherri; Usue Pérez-López; Francesco Micaelli; Jon Miranda-Apodaca; Amaia Mena-Petite; Alberto Muñoz-Rueda; Mike Frank Quartacci
      Abstract: Publication date: Available online 7 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Cristina Sgherri, Usue Pérez-López, Francesco Micaelli, Jon Miranda-Apodaca, Amaia Mena-Petite, Alberto Muñoz-Rueda, Mike Frank Quartacci
      Both salt stress and high CO2 level, besides influencing secondary metabolism, can affect oxidative status of plants mainly acting in an opposite way with salinity provoking oxidative stress and elevated CO2 alleviating it. The aim of the present work was to study the changes in the composition of phenolic acids and flavonoids as well as in the antioxidant activity in two differently pigmented lettuce cvs (green or red leaf) when submitted to salinity (200 mM NaCl) or elevated CO2 (700 ppm) or to their combination in order to evaluate how a future global change can affect lettuce quality. Following treatments, the red cv. always maintained higher levels of antioxidant secondary metabolites as well as antioxidant activity, proving to be more responsive to altered environmental conditions than the green one. Overall, these results suggest that the application of moderate salinity or elevated CO2, alone or in combination, can induce the production of some phenolics that increase the health benefits of lettuce. In particular, moderate salinity was able to induce the synthesis of the flavonoids quercetin, quercetin-3-O-glucoside, quercetin-3-O-glucuronide and quercitrin. Phenolics-enrichment as well as a higher antioxidant capacity were also observed under high CO2 with the red lettuce accumulating cyanidin, free chlorogenic acid, conjugated caffeic and ferulic acid as well as quercetin, quercetin-3-O-glucoside, quercetin-3-O-glucuronide, luteolin-7-O-glucoside, rutin, quercitrin and kaempferol. When salinity was present in combination with elevated CO2, reduction in yield was prevented and a higher presence of phenolic compounds, in particular luteolin, was observed compared to salinity alone.
      Graphical abstract image

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.006
       
  • Chitosan-induced immunity in Camellia sinensis (L.) O. Kuntze against
           blister blight disease is mediated by nitric-oxide
    • Authors: Swarnendu Chandra; Nilanjan Chakraborty; Koustubh Panda; Krishnendu Acharya
      Abstract: Publication date: Available online 7 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Swarnendu Chandra, Nilanjan Chakraborty, Koustubh Panda, Krishnendu Acharya
      Blister blight disease, caused by an obligate biotrophic fungal pathogen, Exobasidium vexans Massee is posing a serious threat for tea cultivation in Asia. As the use of chemical pesticides on tea leaves substantially increases the toxic risks of tea consumption, serious attempts are being made to control such pathogens by boosting the intrinsic natural defense responses against invading pathogens in tea plants. In this study, the nature and durability of resistance offered by chitosan and the possible mechanism of chitosan-induced defense induction in Camellia sinensis (L.) O. Kuntze plants against blister blight disease were investigated. Foliar application of 0.01% chitosan solution at 15 days interval not only reduced the blister blight incidence for two seasons, but also maintained the induced expressions of different defense related enzymes and total phenol content compared to the control. Defense responses induced by chitosan were found to be down regulated under NO deficient conditions in vivo, indicating that the observed chitosan-induced resistance is probably activated via NO signaling. Such role of NO in host defense response was further established by application of the NO donor, sodium nitroprusside (SNP), which produced similar defense responses accomplished through chitosan treatment. Taken together, our results suggest that increased production of NO in chitosan-treated tea plants may play a critical role in triggering the innate defense responses effective against plant pathogens, including that causing the blister blight disease.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.008
       
  • Preferentially enhancing anti-cancer isothiocyanates over glucosinolates
           in broccoli sprouts: How NaCl and salicylic acid affect their formation
    • Authors: Azadeh Esfandiari; Ali Saei; Marian J. McKenzie; Adam Matich; Mesbah Babalar; Donald A. Hunter
      Abstract: Publication date: Available online 7 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Azadeh Esfandiari, Ali Saei, Marian J. McKenzie, Adam Matich, Mesbah Babalar, Donald A. Hunter
      Broccoli (Brassica oleracea L. var. italica) sprouts contain glucosinolates (GLs) that when hydrolysed yield health promoting isothiocyanates such as sulforaphane (SF). SF content can be increased by salt (NaCl) stress, although high salt concentrations negatively impact plant growth. Salicylic acid (SA) treatments can attenuate the negative effects of salt on growth. To test whether sprout isothiocyanate content could be elevated without sprout growth being compromised, broccoli seed were germinated and grown for seven days in salt (0, 80 and 160 mM) alone and in combination with 100 μM SA. Increasing concentrations of salt lowered transcript accumulation of GL biosynthetic genes which was reflected in lowered content of Gluconapin, 4-methoxyglucobrassicin and neoglucobrassicin glucosinolates. Other glucosinolates such as glucoraphanin did not alter significantly. Salt (160 mM) increased transcript abundance of the GL hydrolytic gene MYROSINASE (BoMYO) and its cofactor EPITHIOSPECIFIER MODIFIER1 (BoESM1) whose encoded product directs MYROSINASE to produce isothiocyanate rather than nitrile forms. SF content was increased 6-fold by the 160 mM salt treatment, but the salt treatment reduced percentage seed germination, slowed seed germination, and reduced the elongation of the sprout hypocotyls. This growth inhibition was prevented if 100 μM SA was included with the salt treatment. These findings suggest that the increase in SF production by salt occurs in part because of increased transcript abundance of genes in the hydrolytic pathway and that this transcriptional enhancement occurs independently of salts more general negative impact on sprout growth.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.003
       
  • Relationship among color development, anthocyanin and pigment-related gene
           expression in ‘Crimson Seedless’ grapes treated with abscisic acid and
           sucrose
    • Authors: Daniela Olivares; Carolina Contreras; Victoria Muñoz; Sebastián Rivera; Mauricio González-Agüero; Julio Retamales; Bruno G. Defilippi
      Abstract: Publication date: Available online 6 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Daniela Olivares, Carolina Contreras, Victoria Muñoz, Sebastián Rivera, Mauricio González-Agüero, Julio Retamales, Bruno G. Defilippi
      ‘Crimson Seedless’ is one of the most important table grape varieties in Chile, but under certain environmental conditions, the fruit exhibits inadequate red color development, causing economic losses due to lower product quality. The use of plant growth regulators, such as abscisic acid (ABA) and ethylene, during development increases the anthocyanin content of the skin, improving the color of the berry. Recently, sucrose has been identified as a signaling molecule capable of regulating the expression of genes of the anthocyanin biosynthesis pathway. The aim of this study was to analyze the effect of application of ABA and/or sucrose on color development and their relationship with anthocyanin metabolism. Applications of ABA (400 ppm or 200 ppm) and/or sucrose (90 mM) were performed close to the véraison stage. During development and at harvest, quality attributes such as berry firmness, total soluble solids and titratable acidity were not affected by these treatments. Increased red color development was observed in fruits treated with ABA and/or sucrose, due to accumulation of anthocyanins. Fruits subjected to sucrose treatment showed higher levels of anthocyanins than untreated fruits but lower levels than fruits treated with ABA. Increased expression of genes involved in anthocyanin biosynthesis was observed in ABA- and sucrose-treated fruits compared to untreated fruits. Based on these findings, we demonstrated that sucrose improved fruit color development by increasing synthesis and accumulation of anthocyanins, thus allowing earlier harvests and improving table grape quality.

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.007
       
  • Cuticular wax coverage and composition differ among organs of Taraxacum
           officinale
    • Authors: Yanjun Guo; Lucas Busta; Reinhard Jetter
      Abstract: Publication date: Available online 6 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Yanjun Guo, Lucas Busta, Reinhard Jetter
      Primary plant surfaces are coated with hydrophobic cuticular waxes to minimize non-stomatal water loss. Wax compositions differ greatly between plant species and, in the few species studied systematically so far, also between organs, tissues, and developmental stages. However, the wax mixtures of more species in diverse plant families must be investigated to assess overall wax variability, and ultimately to correlate organ-specific composition with local water barrier properties. Here, we present comprehensive analyses of the waxes covering five organs of Taraxacum officinale (dandelion), to help close a gap in our understanding of wax chemistry in the Asteraceae family. First, novel wax constituents of the petal wax were identified as C25 6,8- and 8,10-ketols as well as C27 6,8- and 8,10-ketols. Ten other component classes (fatty acids, primary alcohols, esters, aldehydes, alkanes, ketols, triterpenols, triterpene acetates, sterols, and tocopherols) were detected in the wax mixtures covering leaves, peduncles, and petals, as well as fruit beaks and pappi. Wax coverages varied from 5 μg/cm2 on peduncles to 37 μg/cm2 on petals. Alcohols predominated in leaf wax, while both alcohols and alkanes were found in similar amounts on peduncles and petals, and mainly alkanes were on the fruit beak and pappus. Chain length distributions within the wax compound classes were similar between organs, centered around C26 for fatty acids, alcohols, and aldehydes, and C29 for alkanes. However, the quantities of homologs with longer chain lengths varied substantially between organs, reaching well beyond C30 on all surfaces except leaves, suggesting differences in elongation enzymes determining the alkyl chain structures. The detailed wax profiles presented here will serve as basis for future investigations into wax biosynthesis in the Asteraceae and into wax functions on different dandelion organs.
      Graphical abstract image

      PubDate: 2017-04-12T15:52:06Z
      DOI: 10.1016/j.plaphy.2017.04.004
       
  • Evaluation of buffers toxicity in tobacco cells: Homopiperazine-1,4-bis
           (2-ethanesulfonic acid) is a suitable buffer for plant cells studies at
           low pH
    • Authors: Borgo
      Abstract: Publication date: June 2017
      Source:Plant Physiology and Biochemistry, Volume 115
      Author(s): Lucélia Borgo
      Low pH is an important environmental stressor of plant root cells. Understanding the mechanisms of stress and tolerance to acidity is critical; however, there is no widely accepted pH buffer for studies of plant cells at low pH. Such a buffer might also benefit studies of Al toxicity, in which buffering at low pH is also important. The challenge is to find a buffer with minimal cellular effects. We examined the cytotoxicity and possible metabolic disturbances of four buffers that have adequate pKa values and potential use for studies in the pH range of 4.0–5.0. These were homopipes (homopiperazine-1,4-bis (2-ethanesulfonic acid); pKa1 4.4), 3,3-dimethylglutaric acid (pKa1 3.73), β-alanine (pKa1 3.70) and potassium biphthalate (pKa1 2.95; pKa2 5.41). First, tobacco BY-2 cells were grown in a rich medium containing 10 mM of each buffer or MES (2-(N-morpholino) ethanesulfonic acid) as a control, with the pH initially adjusted to 5.7. β-alanine was clearly toxic and dimethylgluturate and biphthalate were found to be cytostatic, in which no culture growth occurred but cell viability was either unaffected or decreased only after 5 days. Only homopipes allowed normal culture growth and cell viability. Homopipes (10 mM) was then tested in cell cultures with an initial pH of 4.3 ± 0.17 in minimal medium to examine whether its undissociated species (H2A) displayed any cellular effects and no cytotoxic effects were observed. It is possible to conclude that among tested buffers, homopipes is the most suitable for studies at low pH, and may be especially useful for aluminum toxicity experiments.

      PubDate: 2017-04-04T15:47:02Z
       
  • The heterologous expression of a chrysanthemum TCP-P transcription factor
           CmTCP14 suppresses organ size and delays senescence in Arabidopsis
           thaliana
    • Authors: Ting Zhang; Yixin Qu; Haibin Wang; Jingjing Wang; Aiping Song; Yueheng Hu; Sumei Chen; Jiafu Jiang; Fadi Chen
      Abstract: Publication date: Available online 2 April 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Ting Zhang, Yixin Qu, Haibin Wang, Jingjing Wang, Aiping Song, Yueheng Hu, Sumei Chen, Jiafu Jiang, Fadi Chen
      TCP transcription factors are important for plant growth and development, but their activity in chrysanthemum (Chrysanthemum morifolium) has not been thoroughly explored. Here, a chrysanthemum TCP-P sequence, which encodes a protein harboring the conserved basic helix-loop-helix (bHLH) motif, was shown to be related phylogenetically to the Arabidopsis thaliana gene AtTCP14. A yeast-one hybrid assay showed that the encoding protein had no transcriptional activation ability, and a localization experiment indicated that it was localized in the nucleus. Transcription profiling established that the gene was most active in the stem and leaf. Its heterologous expression in A. thaliana down-regulated certain cell cycle-related genes, reduced the size of various organs and increased the chlorophyll and carotenoid contents of the leaf which led to delayed senescence and a prolonged flowering period. Moreover, by screening the cDNA library of chrysanthemum, we found that the CmTCP14 can interact with CmFTL2 and some CmDELLAs.

      PubDate: 2017-04-04T15:47:02Z
      DOI: 10.1016/j.plaphy.2017.03.026
       
  • Gene regulation network behind drought escape, avoidance and tolerance
           strategies in black poplar (Populus nigra L.)
    • Authors: Kubilay Yıldırım; Zeki Kaya
      Abstract: Publication date: Available online 28 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Kubilay Yıldırım, Zeki Kaya
      Drought is the major environmental problem limiting the productivity and survival of plant species. Here, previously identified three black poplar genotypes having contrasting response to drought were subjected to gradual soil water depletion in a pot trial to identify their physiological, morphological and antioxidation related adaptations. We also performed a microarray based transcriptome analyses on the leaves of genotypes by using Affymetrix poplar Genome Array containing 56,000 transcripts. Phenotypic analyses of each genotype confirmed their differential adaptations to drought that could be classified as drought escape, avoidance and tolerance. Comparative transcriptomic analysis indicated highly divergent gene expression patterns among the genotypes in response to drought and post drought re-watering (PDR). We identified 10641, 3824 and 9411 transcripts exclusively regulated in drought escape, avoidance and tolerant genotypes, respectively. The key genes involved in metabolic pathways, such as carbohydrate metabolism, photosynthesis, lipid metabolism, generation of precursor metabolites/energy, protein folding, redox homeostasis, secondary metabolic process and cell wall component biogenesis, were affected by drought stresses in the leaves of these genotypes. Transcript isoforms showed increased expression specificity in the genes coding for bark storage proteins and small heat shock proteins in drought tolerant genotype. On the other hand, drought-avoiding genotype specifically induced the transcripts annotated to the genes functional in secondary metabolite production that linked to enhanced leaf water content and growth performance under drought stress. Transcriptome profiling of drought escape genotype indicated specific regulation of the genes functional in programmed cell death and leaf senescence. Specific upregulation of GTP cyclohydrolase II and transcription factors (WRKY and ERFs) in only this genotype were associated to ROS dependent signalling pathways and gene regulation network responsible in induction of many degrading enzymes acting on cell wall carbohydrates, fatty acids and proteins under drought stress. Our findings provide new insights into the transcriptome dynamics and components of regulatory network associated with drought adaptation strategies.

      PubDate: 2017-03-28T15:42:25Z
      DOI: 10.1016/j.plaphy.2017.03.020
       
  • Proteomics analysis of maize (Zea mays L.) grain based on iTRAQ reveals
           molecular mechanisms of poor grain filling in inferior grains
    • Authors: Tao Geng; Peng Liu Shuting Dong Jiwang Zhang Bin Zhao
      Abstract: Publication date: Available online 11 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Tao Yu, Geng Li, Peng Liu, Shuting Dong, Jiwang Zhang, Bin Zhao
      In maize, inferior grains (IG) located on the upper part of the ear have poor grain filling process compared to superior grains (SG) located on the middle and lower parts of the ear. This difference limits satisfactory yield and quality; however, the underlying molecular mechanisms remain unknown. Here, using the isobaric tag for relative and absolute quantification (iTRAQ) technology, the proteomes of IG and SG during early and middle grain filling stages were investigated. In total, 4720 proteins were identified in maize grain and 305 differentially accumulated proteins (DiAPs) were detected between IG and SG. These DiAPs were involved in diverse cellular and metabolic processes with preferred distribution in protein synthesis/destination and metabolism. Compared to SG, DiAPs related to cell growth/division and starch synthesis were lag-accumulated and down-regulated in IG, respectively, resulting in smaller sink sizes and lower sink activities in IG. Meanwhile, impediment of the glycolysis pathway in IG may lead to reduce energy supply and building materials for substance synthesis. Additionally, reactive oxygen species (ROS) homeostasis and the defense system were disturbed in IG, which might lead to reduce protection against various environmental stresses. The present study provides new information on the proteomic differences between IG and SG, and explains possible molecular mechanisms for poor grain filling in IG.

      PubDate: 2017-03-17T10:05:08Z
       
  • Transcriptional and computational study of expansins differentially
           expressed in response to inclination in radiata pine
    • Authors: Patricio Mateluna; Felipe Valenzuela-Riffo; Luis Morales-Quintana; Raúl Herrera; Patricio Ramos
      Abstract: Publication date: Available online 9 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Patricio Mateluna, Felipe Valenzuela-Riffo, Luis Morales-Quintana, Raúl Herrera, Patricio Ramos
      Plants have the ability to reorient their vertical growth when exposed to inclination. This response can be as quick as 2 h in inclined young pine (Pinus radiata D. Don) seedlings, with over accumulation of lignin observed after 9 days s. Several studies have identified expansins involved in cell expansion among other developmental processes in plants. Six putative expansin genes were identified in cDNA libraries isolated from inclined pine stems. A differential transcript abundance was observed by qPCR analysis over a time course of inclination. Five genes changed their transcript accumulation in both stem sides in a spatial and temporal manner compared with non-inclined stem. To compare these expansin genes, and to suggest a possible mechanism of action at molecular level, the structures of the predicted proteins were built by comparative modeling methodology. An open groove on the surface of the proteins composed of conserved residues was observed. Using a cellulose polymer as ligand the protein-ligand interaction was evaluated, with the results showing differences in the protein-ligand interaction mode. Differences in the binding energy interaction can be explained by changes in some residues that generate differences in electrostatic surface in the open groove region, supporting the participation of six members of multifamily proteins in this specific process. The data suggests participation of different expansin proteins in the dissembling and remodeling of the complex cell wall matrix during the reorientation response to inclination.
      Graphical abstract image

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.03.005
       
  • In vivo transport of three radioactive [18F]-fluorinated deoxysucrose
           analogs by the maize sucrose transporter ZmSUT1
    • Authors: Thu M. Tran; Carissa S. Hampton; Tom W. Brossard; Michael Harmata; J. David Robertson; Silvia S. Jurisson; David M. Braun
      Abstract: Publication date: Available online 8 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Thu M. Tran, Carissa S. Hampton, Tom W. Brossard, Michael Harmata, J. David Robertson, Silvia S. Jurisson, David M. Braun
      Sucrose transporter (SUT) proteins translocate sucrose across cell membranes; however, mechanistic aspects of sucrose binding by SUTs are not well resolved. Specific hydroxyl groups in sucrose participate in hydrogen bonding with SUT proteins. We previously reported that substituting a radioactive fluorine-18 [18F] at the C-6′ position within the fructosyl moiety of sucrose did not affect sucrose transport by the maize (Zea mays) ZmSUT1 protein. To determine how 18F substitution of hydroxyl groups at two other positions within sucrose, the C-1′ in the fructosyl moiety or the C-6 in the glucosyl moiety, impact sucrose transport, we synthesized 1′-[F18]fluoro-1′-deoxysucrose and 6-[F18]fluoro-6-deoxysucrose ([18F]FDS) analogs. Each [18F]FDS derivative was independently introduced into wild-type or sut1 mutant plants, which are defective in sucrose phloem loading. All three (1′-, 6′-, and 6-) [18F]FDS derivatives were efficiently and equally translocated, similarly to carbon-14 [14C]-labeled sucrose. Hence, individually replacing the hydroxyl groups at these positions within sucrose does not interfere with substrate recognition, binding, or membrane transport processes, and hydroxyl groups at these three positions are not essential for hydrogen bonding between sucrose and ZmSUT1. [18F]FDS imaging afforded several advantages compared to [14C]-sucrose detection. We calculated that 1′-[18F]FDS was transported at approximately a rate of 0.90 ± 0.15 m.h-1 in wild-type leaves, and at 0.68 ± 0.25 m.h-1 in sut1 mutant leaves. Collectively, our data indicated that [18F]FDS analogs are valuable tools to probe sucrose-SUT interactions and to monitor sucrose transport in plants.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.03.006
       
  • Nitrogen use strategies of seedlings from neotropical tree species of
           distinct successional groups
    • Authors: Halley Caixeta Oliveira; Ligia Maria Inocêncio da Silva; Letícia Dias de Freitas; Tatiane Viegas Debiasi; Nidia Mara Marchiori; Marcos Pereira Marinho Aidar; Edmilson Bianchini; José Antonio Pimenta; Renata Stolf-Moreira
      Abstract: Publication date: Available online 6 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Halley Caixeta Oliveira, Ligia Maria Inocêncio da Silva, Letícia Dias de Freitas, Tatiane Viegas Debiasi, Nidia Mara Marchiori, Marcos Pereira Marinho Aidar, Edmilson Bianchini, José Antonio Pimenta, Renata Stolf-Moreira
      Few studies have analyzed the strategies of neotropical tree seedlings for absorbing, translocating and assimilating the nitrogen. Here, we compared the nitrogen use strategies of seedlings from six tree species that are native to the Brazilian Atlantic Forest and that belong to different successional groups: Trema micrantha, Heliocarpus popayanensis and Cecropia pachystachya (pioneers), Cariniana estrellensis, Eugenia brasiliensis and Guarea kunthiana (non-pioneers). The effects of cultivating seedlings with nitrate or ammonium on the growth, physiology and nitrogen metabolism were analyzed. Nitrate-grown pioneer species had much higher leaf nitrate reductase activity than non-pioneer ones, but non-pioneer seedlings were also able to use nitrate as a nitrogen source. In addition to this remarkable difference between the groups in the capacity for leaf nitrate assimilation, substantial variations in the nitrogen use strategies were observed within the successional classes. Differently from the other non-pioneers, the canopy species C. estrellensis seemed to assimilate nitrate mainly in the leaves. Morphophysiological analyses showed a gradient of ammonium toxicity response, with E. brasiliensis as the most tolerant species, and T. micrantha and H. popayanensis as the most sensitive ones. Guarea kunthiana showed a relatively low tolerance to ammonium and an unusual high translocation of this cation in the xylem sap. In contrast to the other pioneers, C. pachystachya had a high plasticity in the use of nitrogen sources. Overall, these results suggest that nitrogen use strategies of neotropical tree seedlings were not determined solely by their successional position.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.03.003
       
  • Dioscorea alata tuber proteome analysis shows over thirty dioscorin
           isoforms and novel tuber proteins
    • Authors: Shruti Sharma; Ravi Gupta; Renu Deswal
      Abstract: Publication date: Available online 6 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Shruti Sharma, Ravi Gupta, Renu Deswal
      In Dioscorea, dioscorin (31 kDa) is the major storage protein constituting 85% of the total tuber proteins. An integrated proteomic and biochemical approach was used to understand the physiological role of dioscorin in the two contrasting growth stages (germinating and mature tuber). HPLC analysis showed 3 fold reduction in mannitol and 12.88 and 1.24 fold increase in sucrose and maltose in the germinating tuber. A 1.8 and 3 fold increase in sucrose phosphate synthase and mannitol dehydrogenase activity respectively was observed in the germinating tuber while a 2 fold higher invertase probably lowers the sucrose accumulation in the mature tuber. SDS-PAGE and 2-D maps of the mature and germinating tubers confirmed depletion (more than 50%) of dioscorin on germination. Dioscorin was purified using ion exchange and gel filtration chromatography with 43.32 fold purification and 38.16 yield. Out of a trail of 35 spots at 31 kDa only 12 spots (identified as dioscorin isoforms) were present in the 2D gel of the purified fraction. To search for other tuber proteins besides dioscorin, the unbound fractions of DEAE column were analysed by 2DGE. DREB 1A, caffeic acid 3-O-methyltransferase and Rab-1 small GTP binding protein were identified perhaps for the first time in the Dioscorea proteome. The interactome analysis revealed these to be involved in oxidative stress, carotenoid synthesis and vesicular transport. This is perhaps the first attempt to identify tuber proteome (although limited) and to understand the physiological significance of these proteins.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.03.001
       
  • TeA is a key virulence factor for Alternaria alternata (Fr.) Keissler
           infection of its host
    • Authors: Ye Kang; Hongwei Feng; Jingxu Zhang; Shiguo Chen; Bernal E. Valverde; Sheng Qiang
      Abstract: Publication date: Available online 4 March 2017
      Source:Plant Physiology and Biochemistry
      Author(s): Ye Kang, Hongwei Feng, Jingxu Zhang, Shiguo Chen, Bernal E. Valverde, Sheng Qiang
      A toxin-deficient mutant strain, HP001 mutant of Alternaria alternata, whose mycelium is unable to infect its host, produces little tenuazonic acid (TeA) toxin. How TeA plays a role in initiating host infection by A. alternata remains unclear. In this research we use Imaging-PAM based on chlorophyll fluorescence parameters and transmission electron microscopy to explore the role of TeA toxin during the infection process of A. alternata. Photosystem II damage began even before wild type mycelium infected the leaves of its host, croftonweed (Ageratina adenophora). Compared with the wild type, HP001 mutant produces morphologically different colonies, hyphae with thinner cell walls, has higher reactive oxygen species (ROS) content and lower peroxidase activity, and fails to form appressoria on the host surface. Adding TeA toxin allows the mutant to partially recover these characters and more closely resemble the wild type. Additionally, we found that the mutant is able to elicit disease symptoms when its mycelium is placed on leaves whose epidermis has been manually removed, which indicates that TeA may be determinant in the fungus recognition of its plant host. Lack of TeA toxin appears responsible for the loss of pathogenicity of the HP001 mutant. As a key virulence factor, TeA toxin not only damages the host plant but also is involved in maintaining ROS content, host recognition, inducing appressoria to infect the host and for allowing completion of the infection process.

      PubDate: 2017-03-10T09:18:47Z
      DOI: 10.1016/j.plaphy.2017.03.002
       
 
 
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