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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  [3039 journals]
  • Map-based cloning and characterization of the novel yellow-green leaf gene
           ys83 in rice (Oryza sativa)
    • Authors: Xiaozhi Ma; Xiaoqiu Sun; Chunmei Li; Rui Huan; Changhui Sun; Yang Wang; Fuliang Xiao; Qian Wang; Purui Chen; Furong Ma; Kuan Zhang; Pingrong Wang; Xiaojian Deng
      Pages: 1 - 9
      Abstract: Publication date: February 2017
      Source:Plant Physiology and Biochemistry, Volume 111
      Author(s): Xiaozhi Ma, Xiaoqiu Sun, Chunmei Li, Rui Huan, Changhui Sun, Yang Wang, Fuliang Xiao, Qian Wang, Purui Chen, Furong Ma, Kuan Zhang, Pingrong Wang, Xiaojian Deng
      Leaf-color mutants have been extensively studied in rice, and many corresponding genes have been identified up to now. However, leaf-color mutation mechanisms are diverse and still need further research through identification of novel genes. In the present paper, we isolated a leaf-color mutant, ys83, in rice (Oryza sativa). The mutant displayed a yellow-green leaf phenotype at seedling stage, and then slowly turned into light-green leaf from late tillering stage. In its yellow leaves, photosynthetic pigment contents significantly decreased and the chloroplast development was retarded. The mutant phenotype was controlled by a recessive mutation in a nuclear gene on the short arm of rice chromosome 2. Map-based cloning and sequencing analysis suggested that the candidate gene was YS83 (LOC_Os02g05890) encoding a protein containing 165 amino acid residues. Gene YS83 was expressed in a wide range of tissues, and its encoded protein was targeted to the chloroplast. In the mutant, a T-to-A substitution occurred in coding sequence of gene YS83, which caused a premature translation of its encoded product. By introduction of the wild-type gene, the ys83 mutant recovered to normal green-leaf phenotype. Taken together, we successfully identified a novel yellow-green leaf gene YS83. In addition, number of productive panicles per plant and number of spikelets per panicle only reduced by 6.7% and 7.6%, respectively, meanwhile its seed setting rate and 1000-grain weight (seed size) were not significantly affected in the mutant, so leaf-color mutant gene ys83 could be used as a trait marker gene in commercial hybrid rice production.

      PubDate: 2016-11-24T13:41:53Z
      DOI: 10.1016/j.plaphy.2016.11.007
      Issue No: Vol. 111 (2016)
       
  • Ectopic expression of GA 2-oxidase 6 from rapeseed (Brassica napus L.)
           causes dwarfism, late flowering and enhanced chlorophyll accumulation in
           Arabidopsis thaliana
    • Authors: Jindong Yan; Xiaoying Liao; Reqing He; Ming Zhong; Panpan Feng; Xinmei Li; Dongying Tang; Xuanming Liu; Xiaoying Zhao
      Pages: 10 - 19
      Abstract: Publication date: February 2017
      Source:Plant Physiology and Biochemistry, Volume 111
      Author(s): Jindong Yan, Xiaoying Liao, Reqing He, Ming Zhong, Panpan Feng, Xinmei Li, Dongying Tang, Xuanming Liu, Xiaoying Zhao
      Gibberellins (GAs) are endogenous hormones that play an important role in higher plant growth and development. GA2-oxidase (GA2ox) promotes catabolism and inactivation of bioactive GAs or their precursors. In this study, we identified the GA2-oxidase gene, BnGA2ox6, and found it to be highly expressed in the silique and flower. Overexpression of BnGA2ox6 in Arabidopsis resulted in GA-deficiency symptoms, including inhibited elongation of the hypocotyl and stem, delayed seed germination, and late flowering. BnGA2ox6 overexpression reduced silique growth, but had no effect on seed development. Additionally, BnGA2ox6 overexpression enhanced chlorophyll b and total chlorophyll accumulation, and downregulated mRNA expression levels of the CHL1 and RCCR genes, which are involved in the chlorophyll degradation. These findings suggest that BnGA2ox6 regulates plant hight, silique development, flowering and chlorophyll accumulation in transgenic Arabidopsis.

      PubDate: 2016-11-24T13:41:53Z
      DOI: 10.1016/j.plaphy.2016.11.008
      Issue No: Vol. 111 (2016)
       
  • Identification of caleosin and oleosin in oil bodies of pine pollen
    • Authors: Buntora Pasaribu; Chii-Shiarng Chen; Yue Ken Liao; Pei-Luen Jiang; Jason T.C. Tzen
      Pages: 20 - 29
      Abstract: Publication date: February 2017
      Source:Plant Physiology and Biochemistry, Volume 111
      Author(s): Buntora Pasaribu, Chii-Shiarng Chen, Yue Ken Liao, Pei-Luen Jiang, Jason T.C. Tzen
      Unique proteins including steroleosin, caleosin, oleosin-L, and oleosin-G have been identified in seed oil bodies of pine (Pinus massoniana). In this study, mature pollen grains with wing-like bladders were collected from pine (Pinus elliottii). Ultrastructural studies showed that oil bodies were present in pollen grains, but not the attached bladders, and the presence of oil bodies was further confirmed by fluorescent staining with BODIPY 493/503. Stable oil bodies were successfully purified from pine pollen grains, and analyzed to be mainly composed of triacylglycerols. Putative oleosin and caleosin in pine pollen oil bodies were detected by immunoassaying with antibodies against sesame seed caleosin and lily pollen oleosin. Complete cDNA fragments encoding these two pollen oil-body proteins were obtained by PCR cloning. Sequence alignment showed that pine pollen caleosin (27 kDa) was highly homologous to pine seed caleosin (28 kDa) except for the lack of an appendix of eight residues at the C-terminus in accord with the 1 kDa difference in their molecular masses. Pine pollen oleosin (15 kDa) was highly homologous to pine seed oleosin-G (14 kDa) except for an insertion of eight residues at the N-terminus in accord with the 1 kDa difference in their molecular masses.

      PubDate: 2016-11-24T13:41:53Z
      DOI: 10.1016/j.plaphy.2016.11.010
      Issue No: Vol. 111 (2016)
       
  • UPLC-QTOF analysis reveals metabolomic changes in the flag leaf of wheat
           (Triticum aestivum L.) under low-nitrogen stress
    • Authors: Yang Zhang; Xin-ming Ma; Xiao-chun Wang; Ji-hong Liu; Bing-yan Huang; Xiao-yang Guo; Shu-ping Xiong; Gui-Xiao La
      Pages: 30 - 38
      Abstract: Publication date: February 2017
      Source:Plant Physiology and Biochemistry, Volume 111
      Author(s): Yang Zhang, Xin-ming Ma, Xiao-chun Wang, Ji-hong Liu, Bing-yan Huang, Xiao-yang Guo, Shu-ping Xiong, Gui-Xiao La
      Wheat is one of the most important grain crop plants worldwide. Nitrogen (N) is an essential macronutrient for the growth and development of wheat and exerts a marked influence on its metabolites. To investigate the influence of low nitrogen stress on various metabolites of the flag leaf of wheat (Triticum aestivum L.), a metabolomic analysis of two wheat cultivars under different induced nitrogen levels was conducted during two important growth periods based on large-scale untargeted metabolomic analysis using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF). Multivariate analyses—such as principle components analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA)—were used for data analysis. PCA yielded distinctive clustering information among the samples, classifying the wheat flag samples into two categories: those under normal N treatment and low N treatment. By processing OPLS-DA, eleven secondary metabolites were shown to be responsible for classifying the two groups. The secondary metabolites may be considered potential biomarkers of low nitrogen stress. Chemical analyses showed that most of the identified secondary metabolites were flavonoids and their related derivatives, such as iso-vitexin, iso-orientin and methylisoorientin-2″-O-rhamnoside, etc. This study confirmed the effect of low nitrogen stress on the metabolism of wheat, and revealed that the accumulation of secondary metabolites is a response to abiotic stresses. Meanwhile, we aimed to identify markers which could be used to monitor the nitrogen status of wheat crops, presumably to guide appropriate fertilization regimens. Furthermore, the UPLC-QTOF metabolic platform technology can be used to study metabolomic variations of wheat under abiotic stresses.
      Graphical abstract image

      PubDate: 2016-12-01T02:35:03Z
      DOI: 10.1016/j.plaphy.2016.11.009
      Issue No: Vol. 111 (2016)
       
  • cDNA-AFLP analysis of transcripts induced in chickpea plants by TiO2
           nanoparticles during cold stress
    • Authors: Saeed Amini; Reza Maali-Amiri; Rahmat Mohammadi; Seyyedeh-Sanam Kazemi- Shahandashti
      Pages: 39 - 49
      Abstract: Publication date: February 2017
      Source:Plant Physiology and Biochemistry, Volume 111
      Author(s): Saeed Amini, Reza Maali-Amiri, Rahmat Mohammadi, Seyyedeh-Sanam Kazemi- Shahandashti
      We evaluated the effect of TiO2 nanoparticles (NPs) on cold tolerance (CT) development in two chickpea (Cicer arietinum L.) genotypes (Sel96Th11439, cold tolerant, and ILC533, cold susceptible) by using cDNA-amplified fragment length polymorphism (cDNA-AFLP) technique during the first and sixth days of cold stress (CS) at 4 °C. Selective amplification by primer combinations generated 4200 transcript-derived fragments (TDFs) while 100 of them (2.62%) were differentially expressed. During CS, 60 differentially expressed TDFs of TiO2 NPs-treated plants were cloned and 10 of them produced successfully readable sequences. These data represented different groups of genes involved in metabolism pathways, cellular defense, cell connections and signaling, transcriptional regulation and chromatin architecture. Two out of 10 TDFs were unknown genes with uncharacterized functions or sequences without homology to known ones. The network-based analysis showed a gene-gene relationship in response to CS. Quantitative reverse-transcriptase polymerase chain reaction (qPCR) confirmed differential expression of identified genes (six out of 10 TDFs) with potential functions in CT and showed similar patterns with cDNA-AFLP results. An increase in transcription level of these TDFs, particularly on the first day of CS, was crucial for developing CT through decreasing electrolyte leakage index (ELI) content in tolerant plants compared to susceptible ones, as well as in TiO2 NPs-treated plants compared to control ones. It could also indicate probable role of TiO2 NPs against CS-induced oxidative stress. Therefore, a new application of TiO2 NPs in CT development is suggested for preventing or controlling the damages in field conditions and increasing crop productivity.

      PubDate: 2016-12-01T02:35:03Z
      DOI: 10.1016/j.plaphy.2016.11.011
      Issue No: Vol. 111 (2016)
       
  • Characterization and fine-mapping of a novel premature leaf senescence
           mutant yellow leaf and dwarf 1 in rice
    • Authors: Luchang Deng; Peng Qin; Zhi Liu; Geling Wang; Weilan Chen; Jianhua Tong; Langtao Xiao; Bin Tu; Yuantao Sun; Wei Yan; Hang He; Jun Tan; Xuewei Chen; Yuping Wang; Shigui Li; Bingtian Ma
      Pages: 50 - 58
      Abstract: Publication date: February 2017
      Source:Plant Physiology and Biochemistry, Volume 111
      Author(s): Luchang Deng, Peng Qin, Zhi Liu, Geling Wang, Weilan Chen, Jianhua Tong, Langtao Xiao, Bin Tu, Yuantao Sun, Wei Yan, Hang He, Jun Tan, Xuewei Chen, Yuping Wang, Shigui Li, Bingtian Ma
      Leaves are the main organs in which photosynthates are produced. Leaf senescence facilitates the translocation of photosynthates and nutrients from source to sink, which is important for plant development and especially for crop yield. However, the molecular mechanism of leaf senescence is unknown. Here, we identified a mutant, yellow leaf and dwarf 1 (yld1), which exhibited decreased plant height and premature leaf senescence. Nitroblue tetrazolium and diamiobenzidine staining analyses revealed that the concentrations of reactive oxygen species were higher in yld1 leaves than in wild type leaves. The photosynthetic pigment contents were significantly decreased in yld1. The yld1 chloroplasts had collapsed and were filled with abnormal starch granules. Combining bulk segregant and MutMap gene mapping approaches, the mutation responsible for the yld1 phenotype was mapped to a 7.3 Mb centromeric region, and three non-synonymous single nucleotide polymorphisms located in three novel genes were identified in this region. The expression patterns of the three candidate genes indicated that LOC_Os06g29380 had the most potential for functional verification. Plant hormone measurements showed that salicylic acid was highly accumulated in yld1 leaves when compared with wild type leaves, and yld1 was more sensitive to salicylic acid than wild type. This work lays the foundation for understanding the molecular regulatory mechanism of leaf senescence, and may reveal new connections among the molecular pathways related to leaf senescence, starch metabolism and salicylic acid signaling.

      PubDate: 2016-12-01T02:35:03Z
      DOI: 10.1016/j.plaphy.2016.11.012
      Issue No: Vol. 111 (2016)
       
  • Medicago truncatula genotypes Jemalong A17 and R108 show contrasting
           variations under drought stress
    • Authors: Shi-shuai Luo; Yan-ni Sun; Xue Zhou; Tong Zhu; Li-sha Zhu; Muhammad Arfan; Li-juan Zou; Hong-hui Lin
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Shi-shuai Luo, Yan-ni Sun, Xue Zhou, Tong Zhu, Li-sha Zhu, Muhammad Arfan, Li-juan Zou, Hong-hui Lin
      Drought is one of the most significant abiotic stresses that restrict crop productivity. Medicago truncatula is a model legume species with a wide genetic diversity. We compared the differential physiological and molecular changes of two genotypes of M. truncatula (Jemalong A17 and R108) in response to progressive drought stress and rewatering. The MtNCED and MtZEP activation and higher abscisic acid (ABA) content was observed in Jemalong A17 plants under normal conditions. Additionally, a greater increase in ABA content and expression of MtNCED and MtZEP in Jemalong A17 plants than that of R108 plants were observed under drought conditions. A more ABA-sensitive stomatal closure and a slower water loss was found in excised leaves of Jemalong A17 plants. Meanwhile, Jemalong A17 plants alleviated leaf wilting and maintained higher relative water content under drought conditions. Exposed to drought stress, Jemalong A17 plants exhibited milder oxidative damage which has less H2O2 and MDA accumulation, lower electrolyte leakage and higher chlorophyll content and PSII activity. Furthermore, Jemalong A17 plants enhanced expression of stress-upregulated genes under drought conditions. These results suggest that genotypes Jemalong A17 and R108 differed in their response and adaptation to drought stress. Given the relationship between ABA and these physiological responses, the MtNCED and MtZEP activation under normal conditions may play an important role in regulation of greater tolerance of Jemalong A17 plants to drought stress. The activation of MtNCED and MtZEP may lead to the increase of ABA content which may activate expression of drought-stress-regulated genes and cause a series of physiological resistant responses.

      PubDate: 2016-10-08T11:24:58Z
      DOI: 10.1016/j.plaphy.2016.09.019
      Issue No: Vol. 109 (2016)
       
  • Overexpressing Arabidopsis ABF3 increases tolerance to multiple abiotic
           stresses and reduces leaf size in alfalfa
    • Authors: Zhi Wang; Guoxia Su; Min Li; Qingbo Ke; Soo Young Kim; Hongbing Li; Jin Huang; Bingcheng Xu; Xi-Ping Deng; Sang-Soo Kwak
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Zhi Wang, Guoxia Su, Min Li, Qingbo Ke, Soo Young Kim, Hongbing Li, Jin Huang, Bingcheng Xu, Xi-Ping Deng, Sang-Soo Kwak
      Arabidopsis ABSCISIC ACID-RESPONSIVE ELEMENT-BINDING FACTOR 3 (ABF3), a bZIP transcription factor, plays an important role in regulating multiple stress responses in plants. Overexpressing AtABF3 increases tolerance to various stresses in several plant species. Alfalfa (Medicago sativa L.), one of the most important perennial forage crops worldwide, has high yields, high nutritional value, and good palatability and is widely distributed in irrigated and semi-arid regions throughout the world. However, drought and salt stress pose major constraints to alfalfa production. In this study, we developed transgenic alfalfa plants (cv. Xinjiang Daye) expressing AtABF3 under the control of the sweetpotato oxidative stress-inducible SWPA2 promoter (referred to as SAF plants) via Agrobacterium tumefaciens-mediated transformation. After drought stress treatment, we selected two transgenic lines with high expression of AtABF3, SAF5 and SAF6, for further characterization. Under normal conditions, SAF plants showed smaller leaf size compared to non-transgenic (NT) plants, while no other morphological changes were observed. Moreover, SAF plants exhibited enhanced drought stress tolerance and better growth under drought stress treatment, which was accompanied by a reduced transpiration rate and lower reactive oxygen species contents. In addition, SAF plants showed an increased tolerance to salt and oxidative stress. Therefore, these transgenic AtABF3 alfalfa plants might be useful for breeding forage crops with enhanced tolerance to environmental stress for use in sustainable agriculture on marginal lands.

      PubDate: 2016-10-08T11:24:58Z
      DOI: 10.1016/j.plaphy.2016.09.020
      Issue No: Vol. 109 (2016)
       
  • Cloning and characterization of TaMBD6 homeologues encoding
           methyl-CpG-binding domain proteins in wheat
    • Authors: Ruijie Shi; Jiahui Zhang; Jingyuan Li; Ketao Wang; Haiying Jia; Lin Zhang; Putong Wang; Jun Yin; Fanrong Meng; Yongchun Li
      Pages: 1 - 8
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Ruijie Shi, Jiahui Zhang, Jingyuan Li, Ketao Wang, Haiying Jia, Lin Zhang, Putong Wang, Jun Yin, Fanrong Meng, Yongchun Li
      DNA methylation is a major epigenetic marker in plants that plays a crucial role in transcriptional and developmental regulation. The DNA methylation ‘code’ is thought to be ‘read’ by a set of proteins containing methyl-CpG-binding domain (MBD). However, little is known about MBD genes in common wheat (Triticum aestivum L.). Here, we report the isolation and characterization of TaMBD6 and its homeologues (TaMBD6_A, TaMBD6_B, and TaMBD6_D) in hexaploid wheat. The cDNA was quite different among the three homeologues and InDel mutations were detected in 5′-UTR and coding region. Two types of TRs (tandem repeats) -- TR1 (57 bp) and TR2 (39 bp) -- occurred in the coding region. TaMBD6_B harbored five copies of TR1 and two copies of TR2. In contrast, TaMBD6_A lacked 30 bp between the 2nd and 3rd copy of TR1, while TaMBD6_D was missing two copies of TR1 but had three copies of TR2. TaMBD6_A, TaMBD6_B, and TaMBD6_D encoded 435, 446, and 420 amino acids, respectively. Structural analysis of TaMBD6 protein indicated that each of the three homeologues had an identical MBD domain at the N-terminal, as well as a typical nuclear localization signal. Although genomics analysis showed that two introns were included, the length of the first intron varied from 3100 bp to 3471 bp and their sequences were very different. Expression analysis demonstrated that the transcription level of TaMBD6 began to increase gradually in developing grains at 15 days after pollination while decreasing significantly in endosperm and embryo tissues during germination. Expression of TaMBD6 appeared to be positively correlated with starch metabolism in the endosperm but was negatively correlated with embryo formation and sprouting. We were also interested to learn that TaMBD6 homeologues were differentially expressed in developing wheat plants and that their expression patterns were variously affected by vernalization treatment. Further investigation revealed that TaMBD6 was induced by prolonged chilling, indicating that the protein is potentially involved in regulating the developmental transition from vegetative to reproductive stages. Although the homeologues generally showed similar differential expression patterns, TaMBD6_D and TaMBD6_B contribute more to the processes of grain development and germination while TaMBD6_A is predominant in mature plants.

      PubDate: 2016-09-11T08:50:25Z
      DOI: 10.1016/j.plaphy.2016.08.024
      Issue No: Vol. 109 (2016)
       
  • Long- and short-term effects of boron excess to root form and function in
           two tomato genotypes
    • Authors: Maria Polsia Princi; Antonio Lupini; Caterina Longo; Anthony J. Miller; Francesco Sunseri; Maria Rosa Abenavoli
      Pages: 9 - 19
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Maria Polsia Princi, Antonio Lupini, Caterina Longo, Anthony J. Miller, Francesco Sunseri, Maria Rosa Abenavoli
      Boron (B) is an essential plant nutrient, but when present in excess it is toxic. Morphological measurements were made to assess the impact of B toxicity on the growth of two different tomato hybrids, Losna and Ikram. Contrasting long and short-term B responses in these tomato hybrids, were observed. Losna showed less toxicity symptoms, maintaining higher growth and showing much less B content in both root and shoot tissues compared to Ikram. Root morphological differences did not explain the tolerance between the two hybrids. Under excess B supply, a significant inhibition on net nitrate uptake rate was observed in Ikram, but not in Losna. This effect may be explained by a decrease of nitrate transporter transcripts in Ikram, which was not measured in Losna. There was a different pattern of B transporter expression in two tomatoes and this can explain the contrasting tolerance observed. Indeed, Losna may be able to exclude or efflux B resulting in less accumulation in the shoot. Particularly, SlBOR4 expression showed significant differences between the tomato hybrids, with higher expression in Losna explaining the improved B-tolerance.

      PubDate: 2016-09-11T08:50:25Z
      DOI: 10.1016/j.plaphy.2016.08.023
      Issue No: Vol. 109 (2016)
       
  • Overexpression of CuZnSOD and APX enhance salt stress tolerance in sweet
           potato
    • Authors: Hui Yan; Qiang Li; Sung-Chul Park; Xin Wang; Ya-ju Liu; Yun-gang Zhang; Wei Tang; Meng Kou; Dai-fu Ma
      Pages: 20 - 27
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Hui Yan, Qiang Li, Sung-Chul Park, Xin Wang, Ya-ju Liu, Yun-gang Zhang, Wei Tang, Meng Kou, Dai-fu Ma
      Abiotic stresses cause accumulation of reactive oxygen species (ROS) in plants, CuZnSOD and APX are first line defenses against ROS caused by oxidative stress. In this study, CuZnSOD and APX were transferred into salt sensitive sweet potato (cv. Xushu 55–2) under control of stress inducible SWPA2 promoter and tolerance to salt stress was evaluated. When 100 mM NaCl was used to treat stem cuttings, transgenic plants showed enhanced tolerance compared to wild type (WT) plants. Rooting was significantly retarded in WT plants whereas all transgenic plants had significantly enhanced root growth under salt stress. Integration of SOD gene was confirmed by southern blot analysis, and the copy number ranged from 1 to 3. The expression levels of CuZnSOD and APX in transgenic plants were significantly increased up to 13.3 and 7.8 folds to WT under salinity conditions, respectively. SOD and APX activity and ROS staining showed enzyme activities of transgenic plants were increased under salt stress. These results show that CuZnSOD and APX have important roles in enhancing the salt tolerance of sweet potato.

      PubDate: 2016-09-11T08:50:25Z
      DOI: 10.1016/j.plaphy.2016.09.003
      Issue No: Vol. 109 (2016)
       
  • Generous hosts: What makes Madagascar periwinkle (Catharanthus roseus) the
           perfect experimental host plant for fastidious bacteria'
    • Authors: Nabil Killiny
      Pages: 28 - 35
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Nabil Killiny
      Although much attention has been paid to the metabolism and biosynthesis of monoterpene alkaloids in Catharanthus roseus, its value as an experimental host for a variety of agriculturally and economically important phytopathogenic bacteria warrants further study. In the present study, we evaluated the chemical composition of the phloem and xylem saps of C. roseus to infer the nutritional requirements of phloem- and xylem-limited phytopathogens. Periwinkle phloem sap consisted of a rich mixture of sugars, organic acids, amino acids, amines, fatty acids, sugar acids and sugar alcohols while xylem contained similar compounds in lesser concentrations. Plant sap analysis may lead to a better understanding of the biology of fastidious Mollicutes and their complex nutritional requirements, and to successful culture of phytoplasmas and other uncultured phloem-restricted bacteria such as Candidatus Liberibacter asiaticus, the causal agent of huanglongbing in citrus.

      PubDate: 2016-09-11T08:50:25Z
      DOI: 10.1016/j.plaphy.2016.09.002
      Issue No: Vol. 109 (2016)
       
  • The involvement of ROS producing aldehyde oxidase in plant response to
           Tombusvirus infection
    • Authors: Timur M. Yergaliyev; Zhadyrassyn Nurbekova; Gulzhamal Mukiyanova; Alua Akbassova; Maxim Sutula; Sayan Zhangazin; Assyl Bari; Zhanerke Tleukulova; Malika Shamekova; Zhaksylyk K. Masalimov; Rustem T. Omarov
      Pages: 36 - 44
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Timur M. Yergaliyev, Zhadyrassyn Nurbekova, Gulzhamal Mukiyanova, Alua Akbassova, Maxim Sutula, Sayan Zhangazin, Assyl Bari, Zhanerke Tleukulova, Malika Shamekova, Zhaksylyk K. Masalimov, Rustem T. Omarov
      The influence of Tomato bushy stunt virus (TBSV) infection on the activity and isoformic composition of aldehyde oxidase and catalase in Nicotiana benthamiana plants was investigated. It was shown that the infection of plants with TBSV results in enhancement of leaf aldehyde oxidase (AO) isoforms AO2 and AO3. Significantly enhanced levels of superoxide radical producing activity of AO isoforms were also detected. This is the first demonstration of involvement of plant AO in defense mechanisms against viral infection. In addition, the infection caused an increased accumulation of hydrogen peroxide, compared to mock-inoculated plants. The virus infection resulted in increased activity of catalase (CAT) and superoxide dismutase (SOD) in roots and leaves of N. benthamiana. Moreover, activation of two additional CAT isoforms was observed in the leaves of plants after virus inoculation. Our findings indicate that the virus infection significantly affects enzymes responsible for the balance of ROS accumulation in plant tissue in response to pathogen attack.

      PubDate: 2016-09-11T08:50:25Z
      DOI: 10.1016/j.plaphy.2016.09.001
      Issue No: Vol. 109 (2016)
       
  • NtPHYB1K326, a homologous gene of Arabidopsis PHYB, positively regulates
           the content of phenolic compounds in tobacco
    • Authors: Jiehong Zhao; Jie Han; Jie Zhang; Zhenhua Li; Jing Yu; Shizhou Yu; Yushuang Guo; Yongfu Fu; Xiaomei Zhang
      Pages: 45 - 53
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Jiehong Zhao, Jie Han, Jie Zhang, Zhenhua Li, Jing Yu, Shizhou Yu, Yushuang Guo, Yongfu Fu, Xiaomei Zhang
      Polyphenols are important secondary metabolites and bioactive compounds in plants. Light is a vital abiotic factor that greatly impacts the content of polyphenols in plants. In spite of their importance the mechanism of polyphenol regulation still remains unknown in tobacco. A phytochrome B homolog, NtPHYB1 K326 , was isolated from Nicotiana tabacum cv. K326 to investigate the role of light receptors in the regulation of polyphenol metabolism in tobacco leaves. Furthermore, role of NtPHYB1 K326 in polyphenol metabolism was analyzed by over-expression and RNAi-silencing approaches. Consistent and complemented results indicated involvement of NtPHYB1 K326 in the regulation of polyphenol metabolism in tobacco leaves. Moreover, high levels of NtPHYB1 K326 transcripts favor the accumulation of chlorogenic acid and its isomers, the key polyphenol component in tobacco leaves. Transcriptome analysis was also carried out for exploring the regulation mechanism of NtPHYB1 K326 in the polyphenol metabolism. Compared with WT, 1665 and 1421 differentially-expressed genes were found in NtPHYB1 K326 -GFP and NtPHYB1 K326 -RNAi transgenic lines, respectively. Among these, about 30 genes were related to phenylpropanoid pathway, which is predominantly involved in synthesis of polyphenols. Further evidences from quantitative RT-PCR confirmed that NtPHYB1 K326 may control phenylpropanoid pathway through regulating the transcription of PAL4 (phenylalanine ammonialyase 4), 4CL1 (4-coumarate:coenzyme A ligase 1) and COMT (caffeic acid 3-O-methyltransferase) genes.

      PubDate: 2016-09-16T09:07:12Z
      DOI: 10.1016/j.plaphy.2016.08.020
      Issue No: Vol. 109 (2016)
       
  • Role of sugars under abiotic stress
    • Authors: Fareen Sami; Mohammad Yusuf; Mohammad Faizan; Ahmad Faraz; Shamsul Hayat
      Pages: 54 - 61
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Fareen Sami, Mohammad Yusuf, Mohammad Faizan, Ahmad Faraz, Shamsul Hayat
      Sugars are the most important regulators that facilitate many physiological processes, such as photosynthesis, seed germination, flowering, senescence, and many more under various abiotic stresses. Exogenous application of sugars in low concentration promote seed germination, up regulates photosynthesis, promotes flowering, delayed senescence under various unfavorable environmental conditions. However, high concentration of sugars reverses all these physiological process in a concentration dependent manner. Thus, this review focuses the correlation between sugars and their protective functions in several physiological processes against various abiotic stresses. Keeping in mind the multifaceted role of sugars, an attempt has been made to cover the role of sugar-regulated genes associated with photosynthesis, seed germination and senescence. The concentration of sugars determines the expression of these sugar-regulated genes. This review also enlightens the interaction of sugars with several phytohormones, such as abscisic acid, ethylene, cytokinins and gibberellins and its effect on their biosynthesis under abiotic stress conditions.

      PubDate: 2016-09-16T09:07:12Z
      DOI: 10.1016/j.plaphy.2016.09.005
      Issue No: Vol. 109 (2016)
       
  • Overexpression of a glyoxalase gene, OsGly I, improves abiotic stress
           tolerance and grain yield in rice (Oryza sativa L.)
    • Authors: Zhengming Zeng; Fangjie Xiong; Xiaohong Yu; Xiaoping Gong; Juntao Luo; Yudong Jiang; Haochi Kuang; Bijun Gao; Xiangli Niu; Yongsheng Liu
      Pages: 62 - 71
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Zhengming Zeng, Fangjie Xiong, Xiaohong Yu, Xiaoping Gong, Juntao Luo, Yudong Jiang, Haochi Kuang, Bijun Gao, Xiangli Niu, Yongsheng Liu
      Glyoxalase I (Gly I) is a component of the glyoxalase system which is involved in the detoxification of methylglyoxal, a byproduct of glycolysis. In the present study, a gene of rice (Oryza sativa L., cv. Nipponbare) encoding Gly I was cloned and characterized. The quantitative real-time PCR analysis indicated that rice Gly I (OsGly I) was ubiquitously expressed in root, stem, leaf, leaf sheath and spikelet with varying abundance. OsGly I was markedly upregulated in response to NaCl, ZnCl2 and mannitol in rice seedlings. For further functional investigation, OsGly I was overexpressed in rice using Agrobacterium-mediated transformation. Transgenic rice lines exhibited increased glyoxalase enzyme activity, decreased methylglyoxal level and improved tolerance to NaCl, ZnCl2 and mannitol compared to wild-type plants. Enhancement of stress tolerance in transgenic lines was associated with reduction of malondialdehyde content which was derived from cellular lipid peroxidation. In addition, the OsGly I-overexpression transgenic plants performed higher seed setting rate and yield. Collectively, these results indicate the potential of bioengineering the Gly I gene in crops.

      PubDate: 2016-09-16T09:07:12Z
      DOI: 10.1016/j.plaphy.2016.09.006
      Issue No: Vol. 109 (2016)
       
  • Responses of photosynthesis, nitrogen and proline metabolism to salinity
           stress in Solanum lycopersicum under different levels of nitrogen
           supplementation
    • Authors: Madhulika Singh; Vijay Pratap Singh; Sheo Mohan Prasad
      Pages: 72 - 83
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Madhulika Singh, Vijay Pratap Singh, Sheo Mohan Prasad
      In the present study, effect of different levels of nitrogen (N0, deprived; N25, sub-optimum; N75, optimum and N150, supra-optimum) in Solanum lycopersicum L. seedlings under NaCl (NaCl1, 0.3 g kg−1 sand and NaCl2, 0.5 g kg−1sand) stress was investigated. Biomass accumulation, pigments, K+ concentration, nitrate and nitrite contents were declined by NaCl in dose dependent manner. As compared to control (N75 without NaCl), fresh weight declined by 4% and 11%, and dry weight by 7 and 13% when seedlings were grown under N75+NaCl1 and N75+NaCl2 combinations, respectively. Furthermore, fluorescence parameters (JIP-test): the size and number of active reaction centres of photosynthetic apparatus (Fv/F0), efficiency of water splitting complex (F0/Fv), quantum yield of primary photochemistry (φP0 or Phi_P0), yield of electron transport per trapped excitation (Ψ0 or Psi_0), the quantum yield of electron transport (φE0), and performance index of PS II (PIABS) and parameters related to energy fluxes per reaction centre (ABS/RC, TR0/RC, ET0/RC and DI0/RC) were also affected by NaCl. However, toxic effect of NaCl on photosystem II photochemistry was ameliorated by N. The lower dose (NaCl1) of NaCl exerts damaging effect on oxidation side of PS II, while higher dose (NaCl2) damages PS II reaction centre and its reduction side. Moreover, control seedlings (N75 without NaCl) when exposed to NaCl1 and NaCl2 exhibited a significant enhancement in respiration rate by 6 and 16%, Na+ accumulation by 111 and 169% in shoot, and 141 and 223% in root and ammonium contents by 19 and 34% respectively. Nitrate and ammonium assimilating enzymes such as nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) and glutamate synthase (GOGAT) were adversely affected by NaCl stress while glutamate dehydrogenase (GDH) showed reverse trend. N addition caused further enhancement in free proline, and activity of Δ1-pyrroline-5-carboxylate synthetase (P5CS), while activity of proline dehydrogenase (ProDH) decreased. The results indicate that different levels of N significantly modulated NaCl-induced damaging effects in tomato seedlings. Furthermore, the results suggest that after N addition Na+, nitrite, nitrate, ammonium contents, nitrogen metabolic enzymes, proline content, and activity of P5CS are favourably regulated, which might be associated with mitigation of NaCl stress and effect was more pronounced with supra-optimum level of N (N150).

      PubDate: 2016-09-21T09:11:31Z
      DOI: 10.1016/j.plaphy.2016.08.021
      Issue No: Vol. 109 (2016)
       
  • Malbec grape (Vitis vinifera L.) responses to the environment: Berry
           phenolics as influenced by solar UV-B, water deficit and sprayed abscisic
           acid
    • Authors: Rodrigo Alonso; Federico J. Berli; Ariel Fontana; Patricia Piccoli; Rubén Bottini
      Pages: 84 - 90
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Rodrigo Alonso, Federico J. Berli, Ariel Fontana, Patricia Piccoli, Rubén Bottini
      High-altitude vineyards receive elevated solar ultraviolet-B (UV-B) levels so producing high quality berries for winemaking because of induction in the synthesis of phenolic compounds. Water deficit (D) after veraison, is a commonly used tool to regulate berry polyphenols concentration in red wine cultivars. Abscisic acid (ABA) plays a crucial role in the acclimation to environmental factors/signals (including UV-B and D). The aim of the present study was to evaluate independent and interactive effects of high-altitude solar UV-B, moderate water deficit and ABA applications on Vitis vinifera cv. Malbec berries. The experiment was conducted during two growing seasons with two treatments of UV-B (+UV-B and –UV-B), watering (+D and –D) and ABA (+ABA and –ABA), in a factorial design. Berry fresh weight, sugar content, fruit yield, phenolic compounds profile and antioxidant capacity (ORAC) were analyzed at harvest. Previous incidence of high UV-B prevented deleterious effects of water deficit, i.e. berry weight reduction and diminution of sugar accumulation. High UV-B increased total phenols (mainly astilbin, quercetin and kaempferol) and ORAC, irrespectively of the combination with other factors. Fruit yield was reduced by combining water deficit and high UV-B or water deficit and ABA. Two applications of ABA were enough to induced biochemical changes increasing total anthocyanins, especially those with higher antioxidant capacity.
      Graphical abstract image

      PubDate: 2016-09-21T09:11:31Z
      DOI: 10.1016/j.plaphy.2016.09.007
      Issue No: Vol. 109 (2016)
       
  • Drought increases cowpea (Vigna unguiculata [L.] Walp.) susceptibility to
           cowpea severe mosaic virus (CPSMV) at early stage of infection
    • Authors: Rodolpho G.G. Silva; Ilka M. Vasconcelos; Thiago F. Martins; Anna L.N. Varela; Pedro F.N. Souza; Ana K.M. Lobo; Fredy D.A. Silva; Joaquim A.G. Silveira; Jose T.A. Oliveira
      Pages: 91 - 102
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Rodolpho G.G. Silva, Ilka M. Vasconcelos, Thiago F. Martins, Anna L.N. Varela, Pedro F.N. Souza, Ana K.M. Lobo, Fredy D.A. Silva, Joaquim A.G. Silveira, Jose T.A. Oliveira
      The physiological and biochemical responses of a drought tolerant, virus-susceptible cowpea genotype exposed to drought stress (D), infected by Cowpea severe mosaic virus (CPSMV) (V), and to these two combined stresses (DV), at 2 and 6 days post viral inoculation (DPI), were evaluated. Gas exchange parameters (net photosynthesis, transpiration rate, stomatal conductance, and internal CO2 partial pressure) were reduced in D and DV at 2 and 6 DPI compared to control plants (C). Photosynthesis was reduced by stomatal and biochemical limitations. Water use efficiency increased at 2 DPI in D, DV, and V, but at 6 DPI only in D and DV compared to C. Photochemical parameters (effective quantum efficiency of photosystem II and electron transport rate) decreased in D and DV compared to C, especially at 6 DPI. The potential quantum efficiency of photosystem II did not change, indicating reversible photoinhibition of photosystem II. In DV, catalase decreased at 2 and 6 DPI, ascorbate peroxidase increased at 2 DPI, but decreased at 6 DPI. Hydrogen peroxide increased at 2 and 6 DPI. Peroxidase increased at 6 DPI and chitinase at 2 and 6 DPI. β-1,3-glucanase decreased in DV at 6 DPI compared to V. Drought increased cowpea susceptibility to CPSMV at 2 DPI, as verified by RT-PCR. However, at 6 DPI, the cowpea plants overcome this effect. Likewise, CPSMV increased the negative effects of drought at 2 DPI, but not at 6 DPI. It was concluded that the responses to combined stresses are not additive and cannot be extrapolated from the study of individual stresses.

      PubDate: 2016-09-25T09:15:02Z
      DOI: 10.1016/j.plaphy.2016.09.010
      Issue No: Vol. 109 (2016)
       
  • Growth and photosynthetic limitation analysis of the Cd-accumulator
           Salicornia ramosissima under excessive cadmium concentrations and optimum
           salinity conditions
    • Authors: Jesús Alberto Pérez-Romero; Susana Redondo-Gómez; Enrique Mateos-Naranjo
      Pages: 103 - 113
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Jesús Alberto Pérez-Romero, Susana Redondo-Gómez, Enrique Mateos-Naranjo
      Cadmium (Cd) is a non-essential element for plants, and its excess impairs plant performance. Physiological impacts of Cd excess are well known in non-tolerant plants, however this information is scarce for Cd-tolerant plants. A glasshouse experiment was designed to investigate the effect of five different Cd levels (0, 0.05, 0.20, 0.65 and 1.35 mM Cd) on the growth, photosynthetic apparatus (PSII chemistry), gas exchange characteristics, photosynthetic pigments profiles, water relations and nutritional balance of the Cd-accumulator Salicornia ramosissima. Ours results confirmed the accumulation capacity of S. ramosissima, as indicated the bioaccumulation factor (BC) greater than 1.0 for all Cd levels. Furthermore, after 21 days of treatment S. ramosissima growth was not highly affected by Cd. Total photosynthetic limitation increased from 38% at 0.05 mM Cd to 70% at 1.35 mM Cd. CO2 diffusion restriction imposed the main contribution to total photosynthetic limitation. Mesophyll conductance reduction was of major importance (with between 69 and 86%), followed by stomatal conductance (with between 9 and 20%). Maximum carboxylation rate (V c,max), remained stable until 0.2 mM Cd, and chlorophyll fluorescence parameters (Fv/Fm, qP) and pigments concentrations were not significantly decreased by increased Cd supply. Finally, S. ramosissima water relations (intrinsic water use efficiency and relative water content) and nutritional level did not highly vary between Cd treatments. Thus, our finding suggested that Cd tolerance S. ramosissima is in certain degree supported by the tolerance of its carbon assimilation enzyme (RuBisCO) and with the high functionality and integrity of the PSII reaction center under Cd excess.

      PubDate: 2016-09-25T09:15:02Z
      DOI: 10.1016/j.plaphy.2016.09.011
      Issue No: Vol. 109 (2016)
       
  • Proteomic comparison of near-isogenic barley (Hordeum vulgare L.)
           germplasm differing in the allelic state of a major senescence QTL
           identifies numerous proteins involved in plant pathogen defense
    • Authors: Katelyn E. Mason; Jonathan K. Hilmer; Walid S. Maaty; Benjamin D. Reeves; Paul A. Grieco; Brian Bothner; Andreas M. Fischer
      Pages: 114 - 127
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Katelyn E. Mason, Jonathan K. Hilmer, Walid S. Maaty, Benjamin D. Reeves, Paul A. Grieco, Brian Bothner, Andreas M. Fischer
      Senescence is the last developmental phase of plant tissues, organs and, in the case of monocarpic senescence, entire plants. In monocarpic crops such as barley, it leads to massive remobilization of nitrogen and other nutrients to developing seeds. To further investigate this process, a proteomic comparison of flag leaves of near-isogenic late- and early-senescing barley germplasm was performed. Protein samples at 14 and 21 days past anthesis were analyzed using both two-dimensional gel-based and label-free quantitative mass spectrometry-based (‘shotgun’) proteomic techniques. This approach identified >9000 barley proteins, and one-third of them were quantified. Analysis focused on proteins that were significantly (p < 0.05; difference ≥1.5-fold) upregulated in early-senescing line ‘10_11’ as compared to late-senescing variety ‘Karl’, as these may be functionally important for senescence. Proteins in this group included family 1 pathogenesis-related proteins, intracellular and membrane receptors or co-receptors (NBS-LRRs, LRR-RLKs), enzymes involved in attacking pathogen cell walls (glucanases), enzymes with possible roles in cuticle modification, and enzymes involved in DNA repair. Additionally, proteases and elements of the ubiquitin-proteasome system were upregulated in line ‘10_11’, suggesting involvement of nitrogen remobilization and regulatory processes. Overall, the proteomic data highlight a correlation between early senescence and upregulated defense functions. This correlation emerges more clearly from the current proteomic data than from a previously performed transcriptomic comparison of ‘Karl’ and ‘10_11’. Our findings stress the value of studying biological systems at both the transcript and protein levels, and point to the importance of pathogen defense functions during developmental leaf senescence.
      Graphical abstract image

      PubDate: 2016-09-25T09:15:02Z
      DOI: 10.1016/j.plaphy.2016.09.008
      Issue No: Vol. 109 (2016)
       
  • GhCaM7-like, a calcium sensor gene, influences cotton fiber elongation and
           biomass production
    • Authors: Yuan Cheng; Lili Lu; Zhaoen Yang; Zhixia Wu; Wenqiang Qin; Daoqian Yu; Zhongying Ren; Yi Li; Lingling Wang; Fuguang Li; Zuoren Yang
      Pages: 128 - 136
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Yuan Cheng, Lili Lu, Zhaoen Yang, Zhixia Wu, Wenqiang Qin, Daoqian Yu, Zhongying Ren, Yi Li, Lingling Wang, Fuguang Li, Zuoren Yang
      Calcium signaling regulates many developmental processes in plants. Calmodulin (CaM) is one of the most conserved calcium sensors and has a flexible conformation in eukaryotes. The molecular functions of CaM are unknown in cotton, which is a major source of natural fiber. In this study, a Gossypium hirsutum L.CaM7-like gene was isolated from upland cotton. Bioinformatics analysis indicated that the GhCaM7 -like gene was highly conserved as compared with Arabidopsis AtCaM7. The GhCaM7 -like gene showed a high expression level in elongating fibers. Expression of β-glucuronidase was observed in trichomes on the stem, leaf and root in transgenic Arabidopsis plants of a PRO GhCaM7-like :GUS fusion. Silencing of the GhCaM7- like gene resulted in decreased fiber length, but also caused reduction in stem height, leaf dimensions, seed length and 100-seed weight, in comparison with those of the control. Reduced expression of the GhCaM7-like gene caused decreased Ca2+ influx in cells of the leaf hypodermis and stem apex, and down-regulation of GhIQD1 (IQ67-domain containing protein), GhAnn2 (Annexins) and GhEXP2 (Expansin). These results indicate that the GhCaM7 -like gene plays a vital role in calcium signaling pathways, and may regulate cotton fiber elongation and biomass production by affecting Ca2+ signatures and downstream signaling pathways of CaM.

      PubDate: 2016-09-25T09:15:02Z
      DOI: 10.1016/j.plaphy.2016.09.009
      Issue No: Vol. 109 (2016)
       
  • Subcellular location of Arabidopsis thaliana subfamily a1
           β-galactosidases and developmental regulation of transcript
           levels of their coding genes
    • Authors: María Moneo-Sánchez; Lucía Izquierdo; Ignacio Martín; Emilia Labrador; Berta Dopico
      Pages: 137 - 145
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): María Moneo-Sánchez, Lucía Izquierdo, Ignacio Martín, Emilia Labrador, Berta Dopico
      The aim of this work is to gain insight into the six members of the a1 subfamily of the β-galactosidases (BGAL) from Arabidopsis thaliana. First, the subcellular location of all these six BGAL proteins from a1 subfamily has been established in the cell wall by the construction of transgenic plants producing the enhanced green fluorescent protein (eGFP) fused to the BGAL proteins. BGAL12 is also located in the endoplasmic reticulum. Our study of the AtBGAL transcript accumulation along plant development indicated that all AtBGAL transcript appeared in initial stages of development, both dark- and light-grown seedlings, being AtBGAL1, AtBGAL2 and AtBGAL3 transcripts the predominant ones in the latter condition, mainly in the aerial part and with levels decreasing with age. The high accumulation of transcript of AtBGAL4 in basal internodes and in leaves at the end of development, and their strong increase after treatment both with BL and H3BO3 point to an involvement of BGAL4 in cell wall changes leading to the cease of elongation and increased rigidity. The changes of AtBGAL transcript accumulation in relation to different stages and conditions of plant development, suggest that each of the different gene products have a plant-specific function and provides support for the proposed function of the subfamily a1 BGAL in plant cell wall remodelling for cell expansion or for cell response to stress conditions.

      PubDate: 2016-09-25T09:15:02Z
      DOI: 10.1016/j.plaphy.2016.09.016
      Issue No: Vol. 109 (2016)
       
  • Genome-wide transcriptome profiling of black poplar (Populus nigra L.)
           under boron toxicity revealed candidate genes responsible in boron uptake,
           transport and detoxification
    • Authors: Kubilay Yıldırım; Senem Uylaş
      Pages: 146 - 155
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Kubilay Yıldırım, Senem Uylaş
      Boron (B) is an essential nutrient for normal growth of plants. Despite its low abundance in soils, it could be highly toxic to plants in especially arid and semi-arid environments. Poplars are known to be tolerant species to B toxicity and accumulation. However, physiological and gene regulation responses of these trees to B toxicity have not been investigated yet. Here, B accumulation and tolerance level of black poplar clones were firstly tested in the current study. Rooted cutting of these clones were treated with elevated B toxicity to select the most B accumulator and tolerant genotype. Then we carried out a microarray based transcriptome experiment on the leaves and roots of this genotype to find out transcriptional networks, genes and molecular mechanisms behind B toxicity tolerance. The results of the study indicated that black poplar is quite suitable for phytoremediation of B pollution. It could resist 15 ppm soil B content and >1500 ppm B accumulation in leaves, which are highly toxic concentrations for almost all agricultural plants. Transcriptomics results of study revealed totally 1625 and 1419 altered probe sets under 15 ppm B toxicity in leaf and root tissues, respectively. The highest induction were recorded for the probes sets annotated to tyrosine aminotransferase, ATP binding cassette transporters, glutathione S transferases and metallochaperone proteins. Strong up regulation of these genes attributed to internal excretion of B into the cell vacuole and existence of B detoxification processes in black poplar. Many other candidate genes functional in signalling, gene regulation, antioxidation, B uptake and transport processes were also identified in this hyper B accumulator plant for the first time with the current study.

      PubDate: 2016-09-25T09:15:02Z
      DOI: 10.1016/j.plaphy.2016.09.015
      Issue No: Vol. 109 (2016)
       
  • Involvement of metabolites in early defense mechanism of oil palm (Elaeis
           guineensis Jacq.) against Ganoderma disease
    • Authors: S.A. Nusaibah; A. Siti Nor Akmar; A.S. Idris; M. Sariah; Z. Mohamad Pauzi
      Pages: 156 - 165
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): S.A. Nusaibah, A. Siti Nor Akmar, A.S. Idris, M. Sariah, Z. Mohamad Pauzi
      Understanding the mechanism of interaction between the oil palm and its key pathogen, Ganoderma spp. is crucial as the disease caused by this fungal pathogen leads to a major loss of revenue in leading palm oil producing countries in Southeast Asia. Here in this study, we assess the morphological and biochemical changes in Ganoderma disease infected oil palm seedling roots in both resistant and susceptible progenies. Rubber woodblocks fully colonized by G. boninense were applied as a source of inoculum to artificially infect the roots of resistant and susceptible oil palm progenies. Gas chromatography-mass spectrometry was used to measure an array of plant metabolites in 100 resistant and susceptible oil palm seedling roots treated with pathogenic Ganoderma boninense fungus. Statistical effects, univariate and multivariate analyses were used to identify key-Ganoderma disease associated metabolic agitations in both resistant and susceptible oil palm root tissues. Ganoderma disease related defense shifts were characterized based on (i) increased antifungal activity in crude extracts, (ii) increased lipid levels, beta- and gamma-sitosterol particularly in the resistant progeny, (iii) detection of heterocyclic aromatic organic compounds, benzo [h] quinoline, pyridine, pyrimidine (iv) elevation in antioxidants, alpha- and beta-tocopherol (iv) degraded cortical cell wall layers, possibly resulting from fungal hydrolytic enzyme activity needed for initial penetration. The present study suggested that plant metabolites mainly lipids and heterocyclic aromatic organic metabolites could be potentially involved in early oil palm defense mechanism against G. boninense infection, which may also highlight biomarkers for disease detection, treatment, development of resistant variety and monitoring.

      PubDate: 2016-09-30T09:18:53Z
      DOI: 10.1016/j.plaphy.2016.09.014
      Issue No: Vol. 109 (2016)
       
  • Methyl jasmonate elicits the biotransformation of geraniol stored as its
           glucose conjugate into methyl geranate in Achyranthes bidentata plant
    • Authors: Shigeru Tamogami; Ganesh K. Agrawal; Randeep Rakwal
      Pages: 166 - 170
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Shigeru Tamogami, Ganesh K. Agrawal, Randeep Rakwal
      To investigate the biotransformation pathway of airborne geraniol by Achyranthes bidentata (A. bidentata), deuterium labeled geraniol was applied with or without methyl jasmonate (MeJA), and the biosynthesized metabolites were analyzed. In A. bidentata leaves, geraniol was conjugated with glucose. The conjugate was then metabolized to afford methyl geranate only under MeJA elicitation. MeJA elicits the biotransformation of geraniol into methyl geranate by inducing the conversion of the intermediate, glucose conjugate of geraniol.

      PubDate: 2016-09-30T09:18:53Z
      DOI: 10.1016/j.plaphy.2016.09.012
      Issue No: Vol. 109 (2016)
       
  • Identification and functional characterization of HbOsmotin from Hevea
           brasiliensis
    • Authors: Zheng Tong; Yong Sun; Dan Wang; Limin Wang; Ling Li; Xueru Meng; Weiqiang Feng; Eve Syrkin Wurtele; Xuchu Wang
      Pages: 171 - 180
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Zheng Tong, Yong Sun, Dan Wang, Limin Wang, Ling Li, Xueru Meng, Weiqiang Feng, Eve Syrkin Wurtele, Xuchu Wang
      Latex in the laticiferous cell network of Hevea brasiliensis tree is composed of cytoplasm that synthesizes natural rubber. Ethylene stimulation of the tree bark enhances latex production partly by prolonging the duration of latex flow during the tapping process. Here, we identified an osmotin-like cDNA sequence (HbOsmotin) from H. brasiliensis that belongs to the pathogenesis-related 5 (PR-5) gene family. The HbOsmotin protein is present in the lutoids of latex in H. brasiliensis, whereas in onion epidermal cells, this protein is predominantly distributed around the cell wall, suggesting that it may be secreted from the cytoplasm. We investigated the effects of exogenous ethylene on HbOsmotin transcription and protein accumulation in rubber latex, and further determined the protein function after osmotic stress in Arabidopsis. In regularly tapped trees, HbOsmotin expression was drastically inhibited in rubber latex after tapping, although the expression was subsequently recovered by ethylene stimulation. However, in virgin plants that had never been tapped, exogenous ethylene application slightly decreased HbOsmotin expression. HbOsmotin overexpression in Arabidopsis showed that HbOsmotin reduced the osmotic stress tolerance of the plant, which likely occurred by raising the water potential. These data indicated that HbOsmotin may contribute to osmotic regulation in laticiferous cells.

      PubDate: 2016-10-08T11:24:58Z
      DOI: 10.1016/j.plaphy.2016.09.017
      Issue No: Vol. 109 (2016)
       
  • Gibberellins producing Bacillus methylotrophicus KE2 supports plant growth
           and enhances nutritional metabolites and food values of lettuce
    • Authors: Ramalingam Radhakrishnan; In-Jung Lee
      Pages: 181 - 189
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Ramalingam Radhakrishnan, In-Jung Lee
      The nutritional quality of green leafy vegetables can be enhanced by application of plant beneficial micro-organisms. The present study was aimed to increase the food values of lettuce leaves by bacterial treatment. We isolated bacterial strain KE2 from Kimchi food and identified as Bacillus methylotrophicus by phylogenetic analysis. The beneficial effect of B. methylotrophicus KE2 on plants was confirmed by increasing the percentage of seed germination of Lactuca sativa L., Cucumis melo L., Glycine max L. and Brassica juncea L. It might be the secretion of array of gibberellins (GA1, GA3, GA7, GA8, GA9, GA12, GA19, GA20, GA24, GA34 and GA53) and indole-acetic acid from B. methylotrophicus KE2. The mechanism of plant growth promotion via their secreted metabolites was confirmed by a significant increase of GA deficient mutant rice plant growth. Moreover, the bacterial association was favor to enhance shoot length, shoot fresh weight and leaf width of lettuce. The higher concentration of protein, amino acids (Asp, Thr, Ser, Glu, Gly, Ala, Leu, Tyr and His), gama-aminobutric acid and fructose was found in bacterial culture (KE2) applied plants. The macro and micro minerals such as K, Mg, Na, P, Fe, Zn and N were also detected as significantly higher quantities in bacteria treated plants than untreated control plants. In addition, the carotenoids and chlorophyll a were also increased in lettuce at bacterial inoculation. The results of this study suggest that B. methylotrophicus KE2 application to soil helps to increase the plant growth and food values of lettuce.
      Graphical abstract image

      PubDate: 2016-10-08T11:24:58Z
      DOI: 10.1016/j.plaphy.2016.09.018
      Issue No: Vol. 109 (2016)
       
  • Cytogenetic evaluation of gold nanorods using Allium cepa test
    • Authors: A. Rajeshwari; Barsha Roy; Natarajan Chandrasekaran; Amitava Mukherjee
      Pages: 209 - 219
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): A. Rajeshwari, Barsha Roy, Natarajan Chandrasekaran, Amitava Mukherjee
      The current study reveals the impact of gold nanorods (NRs) capped with CTAB (cetyltrimethylammonium bromide) or PEG (polyethylene glycol) on Allium cepa. The morphology and surface charge of CTAB- and PEG-capped gold NRs were characterized by electron microscopic and zeta potential analyses. The chromosomal aberrations like clumped chromosome, chromosomal break, chromosomal bridge, diagonal anaphase, disturbed metaphase, laggard chromosome, and sticky chromosome were observed in the root tip cells exposed to different concentrations (0.1, 1, and 10 μg/mL) of CTAB- and PEG-capped gold NRs. We found that both CTAB- and PEG-capped gold NRs were able to induce toxicity in the plant system after 4-h interaction. At a maximum concentration of 10 μg/mL, the mitotic index reduction induced by CTAB-capped gold NRs was 40-fold higher than that induced by PEG-capped gold NRs. The toxicity of gold NRs was further confirmed by lipid peroxidation and oxidative stress analyses. The unbound CTAB also contributed to the toxicity in root tip cells, while PEG alone shows less toxicity to the cells. The vehicle control CTAB contributed to the toxic effects in root tip cells, while PEG alone did not show any toxicity to the cells. The results revealed that even though both the particles have adverse effects on A. cepa, there was a significant difference in the mitotic index and oxidative stress generation in root cells exposed to CTAB-capped gold NRs. Thus, this study concludes that the surface polymerization of gold NRs by PEG can reduce the toxicity of CTAB-capped gold NRs.

      PubDate: 2016-10-14T12:19:46Z
      DOI: 10.1016/j.plaphy.2016.10.003
      Issue No: Vol. 109 (2016)
       
  • Involvement of the Fusarium graminearum cerato-platanin proteins in fungal
           growth and plant infection
    • Authors: Alessandra Quarantin; Anika Glasenapp; Wilhelm Schäfer; Francesco Favaron; Luca Sella
      Pages: 220 - 229
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Alessandra Quarantin, Anika Glasenapp, Wilhelm Schäfer, Francesco Favaron, Luca Sella
      The genome of Fusarium graminearum, a necrotrophic fungal pathogen causing Fusarium head blight (FHB) disease of wheat, barley and other cereal grains, contains five genes putatively encoding for proteins with a cerato-platanin domain. Cerato-platanins are small secreted cysteine-rich proteins possibly localized in the fungal cell walls and also contributing to the virulence. Two of these F. graminearum proteins (FgCPP1 and FgCPP2) belong to the class of SnodProt proteins which exhibit phytotoxic activity in the fungal pathogens Botrytis cinerea and Magnaporthe grisea. In order to verify their contribution during plant infection and fungal growth, single and double gene knock-out mutants were produced and no reduction in symptoms severity was observed compared to the wild type strain on both soybean and wheat spikes. Histological analysis performed by fluorescence microscopy on wheat spikelets infected with mutants constitutively expressing the dsRed confirmed that FgCPPs do not contribute to fungal virulence. In particular, the formation of compound appressoria on wheat paleas was unchanged. Looking for other functions of these proteins, the double mutant was characterized by in vitro experiments. The mutant was inhibited by salt and H2O2 stress similarly to wild type. Though no growth difference was observed on glucose, the mutant grew better than wild type on carboxymethyl cellulose. Additionally, the mutant's mycelium was more affected by treatments with chitinase and β-1,3-glucanase, thus indicating that FgCPPs could protect fungal cell wall polysaccharides from enzymatic degradation.

      PubDate: 2016-10-14T12:19:46Z
      DOI: 10.1016/j.plaphy.2016.10.001
      Issue No: Vol. 109 (2016)
       
  • Molecular characterization, expression, and regulation of Gynostemma
           pentaphyllum squalene epoxidase gene 1
    • Authors: Huihong Guo; Rufang Li; Shibiao Liu; Na Zhao; Shuo Han; Mengmeng Lu; Xiaomin Liu; Xinli Xia
      Pages: 230 - 239
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Huihong Guo, Rufang Li, Shibiao Liu, Na Zhao, Shuo Han, Mengmeng Lu, Xiaomin Liu, Xinli Xia
      Gynostemma pentaphyllum (Thunb.) Makino is a perennial medicinal herb widely distributed in China. This herb contains important medicinal components called gypenosides, which belong to dammarane-type triterpenoid saponins. Squalene epoxidase (SE, EC 1.14.99.7) catalyzes the epoxidation of squalene to form oxidosqualene and is a key regulatory enzyme in triterpenoid saponin biosynthesis. In this study, a SE gene designated as GpSE1 was isolated from G. pentaphyllum leaves. The deduced protein sequence of GpSE1 contained two conserved domains involved in the catalytic function of SE. GpSE1 was expressed as inclusion bodies in Escherichia coli cells, and the HIS-tagged recombinant protein was successfully purified and renatured in vitro. Immunofluorescence indicated that the polygonal reticular fluorescence signal of GpSE1 was significantly stronger in young leaves than in mature leaves and rhizomes. This finding is consistent with the tissue-specific expression pattern of GpSE1 and suggests that the young leaves of G. pentaphyllum mainly serve as the active site of gypenoside synthesis. Methyl jasmonate (MeJA) treatment upregulated GpSE1 expression in both the young and mature leaves of G. pentaphyllum, with greater upregulation in young leaves than in mature leaves. However, the expression of GpSE1 was not enhanced continually with the increase in MeJA concentration. Moreover, the GpSE1 expression was maximally regulated in response to 50 μM MeJA but not to 100 μM MeJA. This result indicates that MeJA exerts a concentration-dependent effect on GpSE1 expression.

      PubDate: 2016-10-14T12:19:46Z
      DOI: 10.1016/j.plaphy.2016.10.002
      Issue No: Vol. 109 (2016)
       
  • A role for CK2 β subunit 4 in the regulation of plant growth, cadmium
           accumulation and H2O2 content under cadmium stress in Arabidopsis thaliana
           
    • Authors: Jiang Zhu; Wen-Shu Wang; Dan Ma; Lin-Yu Zhang; Feng Ren; Ting-Ting Yuan
      Pages: 240 - 247
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Jiang Zhu, Wen-Shu Wang, Dan Ma, Lin-Yu Zhang, Feng Ren, Ting-Ting Yuan
      Protein kinase CK2, which consists of two α and two β subunits, plays an essential role in plant development and is implicated in plant responses to abiotic stresses, including salt and heat. However, the function of CK2 in response to heavy metals such as cadmium (Cd) has not yet been established. In this study, the transgenic line CKB4ox, which overexpresses CKB4 encoding the CK2β subunit and has elevated CK2 activity, was used to investigate the potential role of CK2 in response to Cd stress in Arabidopsis thaliana. Under Cd stress, CKB4ox showed reduced root growth and biomass accumulation as well as decreased chlorophyll and proline contents compared with wild type. Furthermore, increased Cd accumulation and a higher H2O2 content were found in CKB4ox, possibly contributing to the inhibition of CKB4ox growth under Cd stress. Additionally, altered levels of Cd and H2O2 were found to be associated with decreased expression of genes involved in Cd efflux, Cd sequestration and H2O2 scavenging. Taken together, these results suggest that elevated expression of CKB4 and increased CK2 activity enhance the sensitivity of plants to Cd stress by affecting Cd and H2O2 accumulation, including the modulation of genes involved in Cd transport and H2O2 scavenging. This study provides direct evidence for the involvement of plant CK2 in the response to Cd stress.

      PubDate: 2016-10-14T12:19:46Z
      DOI: 10.1016/j.plaphy.2016.10.004
      Issue No: Vol. 109 (2016)
       
  • Senescence-specific change in ROS scavenging enzyme activities and
           regulation of various SOD isozymes to ROS levels in psf mutant rice leaves
           
    • Authors: Fubiao Wang; Jianchao Liu; Lujian Zhou; Gang Pan; Zhaowei Li; Syed-Hassan-Raza Zaidi; Fangmin Cheng
      Pages: 248 - 261
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Fubiao Wang, Jianchao Liu, Lujian Zhou, Gang Pan, Zhaowei Li, Syed-Hassan-Raza Zaidi, Fangmin Cheng
      To clarify the interaction between different antioxidant enzymes for monitoring oxidative stress and ROS burst in rice senescent leaves, we investigated the genotype-dependent alteration in temporal patterns of the O2 •− production rate, H2O2 content, and ROS–scavenging enzyme activities during leaf senescence in two rice genotypes, namely, the premature senescence of flag leaf (psf) mutant and its wild type. Results showed that the psf mutant differed obviously from its wild type in leaf O2 •− generation rate and H2O2 content accumulation, and the decreased activities of SOD, CAT, and APX in the psf leaves were strongly responsible for the increased ROS level and the accelerated leaf senescence. By contrast, the increase in POD activity was positively correlated with the senescence-related enhancement in O2 •− generation in rice leaves. Among various SOD isoforms, Mn–SOD responded sensitively to the increasing O2 •− generation rate, whereas Cu/Zn–SOD remained stable with the progression of leaf senescence. These findings suggest that the senescence-related decline in total SOD activity was mostly attributable to the downregulation of both the translation and transcription of Mn–SOD isoform. This occurrence finally resulted in the collapse of SOD defense system and accelerated leaf senescence for the psf mutant. Furthermore, we presented the possible contribution of several Cu/Zn–SOD expression patterns to the senescence-related O2 •− detoxification in different cell compartments.

      PubDate: 2016-10-21T18:06:42Z
      DOI: 10.1016/j.plaphy.2016.10.005
      Issue No: Vol. 109 (2016)
       
  • The efficient physiological strategy of a tomato landrace in response to
           short-term salinity stress
    • Authors: Tommaso Michele Moles; Antonio Pompeiano; Thais Huarancca Reyes; Andrea Scartazza; Lorenzo Guglielminetti
      Pages: 262 - 272
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Tommaso Michele Moles, Antonio Pompeiano, Thais Huarancca Reyes, Andrea Scartazza, Lorenzo Guglielminetti
      Landraces represent an important part of the biodiversity well-adapted under limiting environmental conditions. We investigated the response of two Southern Italy tomato landraces, the well-known San Marzano (our commercial standard) and a local accession called “Ciettaicale”, to different levels of sodium chloride in water irrigation (from 0 up to 600 mM) for a short-time exposure (one week). The combination of the chlorophyll a fluorescence and gas exchange analyses suggested that Ciettaicale maintained a higher efficiency of photosystem II (PSII) photochemistry and CO2 utilization at high salinity concentrations than San Marzano. Stomatal and non-stomatal limitations occurred in San Marzano according to the reduction of maximum efficiency of PSII photochemistry and the increase of intercellular CO2 concentration. Higher Na+/K+ ratio and higher concentration of total soluble sugars contributed to non-stomatal limitations in San Marzano leaves. These effects were significantly less evident in Ciettaicale. We also observed changes in total antioxidant capacity and leaf pigment content that emphasized the occurrence of modifications in the photosynthetic apparatus according to salt gradient. The more efficient assimilates supply and an integrated root protection system provided by sugars and antioxidants can explain the significantly higher root/shoot ratio in Ciettaicale. Overall, our results suggest that a comprehensive assessment of salinity tolerance in a genotypes comparison could be also obtained evaluating plant response to high salinity levels at early vegetative stage. In addition, further studies will be carried out in order to evaluate the possibility of using Ciettaicale in tomato improvement programs.

      PubDate: 2016-10-21T18:06:42Z
      DOI: 10.1016/j.plaphy.2016.10.008
      Issue No: Vol. 109 (2016)
       
  • An RRM-containing mei2-like MCT1 plays a negative role in the seed
           germination and seedling growth of Arabidopsis thaliana in the presence of
           ABA
    • Authors: Lili Gu; Hyun Ju Jung; Kyung Jin Kwak; Sy Nguyen Dinh; Yeon-Ok Kim; Hunseung Kang
      Pages: 273 - 279
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Lili Gu, Hyun Ju Jung, Kyung Jin Kwak, Sy Nguyen Dinh, Yeon-Ok Kim, Hunseung Kang
      Despite an increasing understanding of the essential role of the Mei2 gene encoding an RNA-binding protein (RBP) in premeiotic DNA synthesis and meiosis in yeasts and animals, the functional roles of the mei2-like genes in plant growth and development are largely unknown. Contrary to other mei2-like RBPs that contain three RNA-recognition motifs (RRMs), the mei2 C-terminal RRM only (MCT) is unique in that it harbors only the last C-terminal RRM. Although MCTs have been implicated to play important roles in plants, their functional roles in stress responses as well as plant growth and development are still unknown. Here, we investigated the expression and functional role of MCT1 (At1g37140) in plant response to abscisic acid (ABA). Confocal analysis of MCT1-GFP-expressing plants revealed that MCT1 is localized to the nucleus. The transcript level of MCT1 was markedly increased upon ABA treatment. Analysis of MCT1-overexpressing transgenic Arabidopsis plants and artificial miRNA-mediated mct1 knockdown mutants demonstrated that MCT1 inhibited seed germination and cotyledon greening of Arabidopsis plants under ABA. The transcript levels of ABA signaling-related genes, such as ABI3, ABI4, and ABI5, were markedly increased in the MCT1-overexpressing transgenic plant. Collectively, these results suggest that ABA-upregulated MCT1 plays a negative role in Arabidopsis seed germination and seedling growth under ABA by modulating the expression of ABA signaling-related genes.

      PubDate: 2016-10-21T18:06:42Z
      DOI: 10.1016/j.plaphy.2016.10.009
      Issue No: Vol. 109 (2016)
       
  • Variation in waterlogging-triggered stomatal behavior contributes to
           changes in the cold acclimation process in prehardened Lolium perenne and
           Festuca pratensis
    • Authors: Barbara Jurczyk; Ewa Pociecha; Franciszek Janowiak; Dawid Kabała; Marcin Rapacz
      Pages: 280 - 292
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Barbara Jurczyk, Ewa Pociecha, Franciszek Janowiak, Dawid Kabała, Marcin Rapacz
      According to predicted changes in climate, waterlogging events may occur more frequently in the future during autumn and winter at high latitudes of the Northern Hemisphere. If excess soil water coincides with the process of cold acclimation for plants, winter survival may potentially be affected. The effects of waterlogging during cold acclimation on stomatal aperture, relative water content, photochemical activity of photosystem II, freezing tolerance and plant regrowth after freezing were compared for two prehardened overwintering forage grasses, Lolium perenne and Festuca pratensis. The experiment was performed to test the hypothesis that changes in photochemical activity initiated by waterlogging-triggered modifications in the stomatal aperture contribute to changes in freezing tolerance. Principal component analysis showed that waterlogging activated different adaptive strategies in the two species studied. The increased freezing tolerance of F. pratensis was associated with increased photochemical activity connected with stomatal opening, whereas freezing tolerance of L. perenne was associated with a decrease in stomatal aperture. In conclusion, waterlogging-triggered stomatal behavior contributed to the efficiency of the cold acclimation process in L. perenne and F. pratensis.

      PubDate: 2016-10-21T18:06:42Z
      DOI: 10.1016/j.plaphy.2016.10.012
      Issue No: Vol. 109 (2016)
       
  • Hydrogen sulfide and proline cooperate to alleviate cadmium stress in
           foxtail millet seedlings
    • Authors: Baohua Tian; Zengjie Qiao; Liping Zhang; Hua Li; Yanxi Pei
      Pages: 293 - 299
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Baohua Tian, Zengjie Qiao, Liping Zhang, Hua Li, Yanxi Pei
      Hydrogen sulfide (H2S) and some functional amino acids in crops have been involved in the defense system against heavy-metal pollution. Here we report the relationships and functions of H2S and proline to cadmium (Cd) stress. Sodium hydrosulfide (NaHS) pretreatment decreased the electrolytic leakage and the malondialdehyde and hydrogen peroxide contents while enhancing photosynthesis in Cd-treated seedlings. Furthermore, pretreatment with NaHS markedly exacerbated Cd-induced alterations in proline content, the activities of proline-5-carboxylate reductase (P5CR) and proline dehydrogenase (PDH), and the transcript levels of P5CR and PDH. When endogenous H2S was scavenged or inhibited by various H2S modulators, the Cd-induced increase in endogenous proline was weakened. Combined pretreatment with H2S and proline was moderately higher in the Cd-stressed growth status, stomata movements and oxidative damage of seedlings compared to a single treatment with H2S or proline. These results suggest that H2S and proline cooperate to alleviate Cd-damage in foxtail millet.

      PubDate: 2016-10-21T18:06:42Z
      DOI: 10.1016/j.plaphy.2016.10.006
      Issue No: Vol. 109 (2016)
       
  • The characterization of the adaptive responses of durum wheat to different
           Fe availability highlights an optimum Fe requirement threshold
    • Authors: Silvia Celletti; Youry Pii; Tanja Mimmo; Stefano Cesco; Stefania Astolfi
      Pages: 300 - 307
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Silvia Celletti, Youry Pii, Tanja Mimmo, Stefano Cesco, Stefania Astolfi
      Plant mechanisms responding to iron (Fe) deficiency have been widely described; it is well known that Strategy II plants, as durum wheat, cope with this stress by increasing both the synthesis and secretion of phytosiderophores (PS). The important contribution of the sulfate assimilatory pathway has been also demonstrated to improve Fe use efficiency in several grasses, such as maize, barley and wheat, most likely because PS are produced from nicotianamine, whose precursor is methionine. Here, the physiological response of durum wheat (T. durum L.) plants - in terms of plant ionome, PS release, thiols content and S pathway-related enzymes – was investigated by gradually decreasing Fe availability that allowed the identification of three specific limit Fe concentrations: 75 μM, 25 μM and 0 μM Fe, i.e. the complete Fe deprivation. At each limit, plants begin to induce different and specific adaptive responses to improve Fe acquisition or to reduce the damage resulting from limited Fe availability. The identification of the Fe availability level below which durum wheat plants start an expensive metabolic reorganization of S and several other elements, could be of benefit not only for an effective cultivation of the crop but also for the grain quality.

      PubDate: 2016-10-21T18:06:42Z
      DOI: 10.1016/j.plaphy.2016.10.010
      Issue No: Vol. 109 (2016)
       
  • Characterization and purification of a bacterial chlorogenic acid esterase
           detected during the extraction of chlorogenic acid from arbuscular
           mycorrhizal tomato roots
    • Authors: Jonathan Negrel; Francine Javelle; Dominique Morandi; Géraldine Lucchi
      Pages: 308 - 318
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Jonathan Negrel, Francine Javelle, Dominique Morandi, Géraldine Lucchi
      A Gram-negative bacterium able to grow using chlorogenic acid (5-caffeoylquinic acid) as sole carbon source has been isolated from the roots of tomato plants inoculated with the arbuscular mycorrhizal fungus Rhizophagus irregularis. An intracellular esterase exhibiting very high affinity (K m = 2 μM) for chlorogenic acid has been extracted and purified by FPLC from the chlorogenate-grown cultures of this bacterium. The molecular mass of the purified esterase determined by SDS-PAGE was 61 kDa and its isoelectric point determined by chromatofocusing was 7.75. The esterase hydrolysed chlorogenic acid analogues (caffeoylshikimate, and the 4- and 3-caffeoylquinic acid isomers), feruloyl esterases substrates (methyl caffeate and methyl ferulate), and even caffeoyl-CoA in vitro but all of them were less active than chlorogenic acid, demonstrating that the esterase is a genuine chlorogenic acid esterase. It was also induced when the bacterial strain was cultured in the presence of hydroxycinnamic acids (caffeic, p-coumaric or ferulic acid) as sole carbon source, but not in the presence of simple phenolics such as catechol or protocatechuic acid, nor in the presence of organic acids such as succinic or quinic acids. The purified esterase was remarkably stable in the presence of methanol, rapid formation of methyl caffeate occurring when its activity was measured in aqueous solutions containing 10–60% methanol. Our results therefore show that this bacterial chlorogenase can catalyse the transesterification reaction previously detected during the methanolic extraction of chlorogenic acid from arbuscular mycorrhizal tomato roots. Data are presented suggesting that colonisation by Rhizophagus irregularis could increase chlorogenic acid exudation from tomato roots, especially in nutrient-deprived plants, and thus favour the growth of chlorogenate-metabolizing bacteria on the root surface or in the mycorhizosphere.

      PubDate: 2016-10-28T21:44:28Z
      DOI: 10.1016/j.plaphy.2016.10.015
      Issue No: Vol. 109 (2016)
       
  • Protein glutathionylation protects wheat (Triticum aestivum Var. Sonalika)
           against Fusarium induced oxidative stress
    • Authors: Subhalaxmi Mohapatra; Bhabatosh Mittra
      Pages: 319 - 325
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Subhalaxmi Mohapatra, Bhabatosh Mittra
      Fusarium induced oxidative stress could be recovered by reversible protein oxidative modification through the process of glutathionylation in co-stressed (low-dose (50 μM) Cd2+ pre-treatment followed by Fusarium inoculation) wheat seedlings. Co-stressed seedlings showed low disease severity index as compared to Fusarium infected seedlings. A reduced level of hydrogen peroxide (H2O2) and carbonyl contents due to irreversible protein oxidation were observed in co-stressed seedlings as compared to Fusarium infected seedlings. Further, a comparative biochemical assay showed an enhanced glutathione content in co-stressed tissues as compared to Fusarium infected tissues. In an investigation, reduced glutathione pre-coated agarose gel beads were used to pull down proteins having affinity with GSH. Fructose-1, 6-bisphosphate aldolase and 3-Phosphoglycerate kinase were observed to be co-existed in co-stressed seedlings when analysed by LC-MS/MS after being processed through protein-pull assay. Co-stressed tissues showed an enhanced free protein thiol content as compared to Fusarium infected tissues. The ratio of free thiol to thiol disulfides was also observed to be increased in co-stressed tissues as compared to Fusarium infected tissues. In contrast, the quantitative assay by Ellman's reagent and qualitative analysis by diagonal gel electrophoresis showed enhanced protein thiol disulfides in Fusarium infected tissues as compared to co-stressed tissues. Further, glutaredoxin, responsible for the reverse reduction of proteins was observed to be enhanced in co-stressed tissues as compared to Fusarium infected tissues. Thus, a low dose Cd2+ triggered glutathionylation is suggestive of offering tolerance against Fusarium induced oxidative stress and protects target proteins from irreversible modification and permanent damage in wheat.

      PubDate: 2016-10-28T21:44:28Z
      DOI: 10.1016/j.plaphy.2016.10.014
      Issue No: Vol. 109 (2016)
       
  • The response of aminopeptidases of Phaseolus vulgaris to drought depends
           on the developmental stage of the leaves
    • Authors: Maruška Budič; Blaž Cigić; Maja Šoštarič; Jerica Sabotič; Vladimir Meglič; Janko Kos; Marjetka Kidrič
      Pages: 326 - 336
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Maruška Budič, Blaž Cigić, Maja Šoštarič, Jerica Sabotič, Vladimir Meglič, Janko Kos, Marjetka Kidrič
      Aminopeptidases, together with other proteases, execute and regulate the total and specifically limited protein breakdown involved in plant physiology, raising the possibility of their involvement in response to drought. We have identified, in leaves of Phaseolus vulgaris L., five aminopeptidases (E.C.3.4.11) whose levels of activity changed when three week old plants were subjected to drought. First, second and third trifoliate leaves were investigated separately. The aminopeptidases were first identified then isolated using ion exchange chromatography of leaf extracts. Three, named PvAP1, PvAP2 and PvAP4, are metallo aminopeptidases with broad substrate specificity, active against substrates conjugated to alanine and lysine. Two others, PvAP3 and PvAP5, are apparently serine aminopeptidases, the former active against substrates conjugated to phenylalanine and leucine, and the latter characterised by narrow specificity against substrates conjugated to phenylalanine. Their apparent molecular weights range from ∼37 kDa to ∼80 kDa. Levels of activity of individual aminopeptidases in both watered and drought stressed plants are shown to depend on the age of leaves. In watered plants they were generally highest in young, and very low in older, trifoliate leaves, the latter with the exception of PvAP5. Drought initiated an almost general increase of their activities, although to different extents, with the exception of PvAP4 and PvAP5 in young trifoliate leaves. Thus, in such studies it is necessary to investigate the effects of drought separately in leaves of different ages in order to elucidate the different complex and probably specific roles of aminopeptidases in the response of common bean to drought.

      PubDate: 2016-10-28T21:44:28Z
      DOI: 10.1016/j.plaphy.2016.10.007
      Issue No: Vol. 109 (2016)
       
  • Excess boron responsive regulations of antioxidative mechanism at
           physio-biochemical and molecular levels in Arabidopsis thaliana
    • Authors: Doğa Selin Kayıhan; Ceyhun Kayıhan; Yelda Özden Çiftçi
      Pages: 337 - 345
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Doğa Selin Kayıhan, Ceyhun Kayıhan, Yelda Özden Çiftçi
      This work was aimed to evaluate the effect of boron (B) toxicity on oxidative damage level, non-enzymatic antioxidant accumulation such as anthocyanin, flavonoid and proline and expression levels of antioxidant enzymes including superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR) and their respective activities as well as expression levels of miR398 and miR408 in Arabidopsis thaliana. Plants were germinated and grown on MS medium containing 1 mM B (1B) and 3 mM B (3B) for 14 d. Toxic B led to a decrease of photosynthetic pigments and an increase in accumulation of total soluble and insoluble sugars in accordance with phenotypically viewed chlorosis of seedlings through increasing level of B concentration. Along with these inhibitions, a corresponding increase in contents of flavonoid, anthocyanin and proline occurred that provoked oxidative stress tolerance. 3B caused a remarkable increase in total SOD activity whereas the activities of APX, GR and CAT remained unchanged as verified by expected increase in H2O2 content. In contrast to GR, the coincidence was found between the expressions of SOD and APX genes and their respective activities. 1B induced mir398 expression, whereas 3B did not cause any significant change in expression of mir408 and mir398. Expression levels of GR genes were coordinately regulated with DHAR2 expression. Moreover, the changes in expression level of MDAR2 was in accordance with changes in APX6 expression and total APX activity, indicating fine-tuned regulation of ascorbate-glutathione cycle which might trigger antioxidative responses against B toxicity in Arabidopsis thaliana.

      PubDate: 2016-10-28T21:44:28Z
      DOI: 10.1016/j.plaphy.2016.10.016
      Issue No: Vol. 109 (2016)
       
  • Potassium retention in leaf mesophyll as an element of salinity tissue
           tolerance in halophytes
    • Authors: William J. Percey; Lana Shabala; Qi Wu; Nana Su; Michael C. Breadmore; Rosanne M. Guijt; Jayakumar Bose; Sergey Shabala
      Pages: 346 - 354
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): William J. Percey, Lana Shabala, Qi Wu, Nana Su, Michael C. Breadmore, Rosanne M. Guijt, Jayakumar Bose, Sergey Shabala
      Soil salinity remains a major threat to global food security, and the progress in crop breeding for salinity stress tolerance may be achieved only by pyramiding key traits mediating plant adaptive responses to high amounts of dissolved salts in the rhizosphere. This task may be facilitated by studying natural variation in salinity tolerance among plant species and, specifically, exploring mechanisms of salinity tolerance in halophytes. The aim of this work was to establish the causal link between mesophyll ion transport activity and plant salt tolerance in a range of evolutionary contrasting halophyte and glycophyte species. Plants were grown under saline conditions in a glasshouse, followed by assessing their growth and photosynthetic performance. In a parallel set of experiments, net K+ and H+ transport across leaf mesophyll and their modulation by light were studied in control and salt-treated mesophyll segments using vibrating non-invasive ion selective microelectrode (the MIFE) technique. The reported results show that mesophyll cells in glycophyte species loses 2–6 fold more K+ compared with their halophyte counterparts. This decline was reflected in a reduced maximum photochemical efficiency of photosystem II, chlorophyll content and growth observed in the glasshouse experiments. In addition to reduced K+ efflux, the more tolerant species also exhibited reduced H+ efflux, which is interpreted as an energy-saving strategy allowing more resources to be redirected towards plant growth. It is concluded that the ability of mesophyll to retain K+ without a need to activate plasma membrane H+-ATPase is an essential component of salinity tolerance in halophytes and halophytic crop plants.

      PubDate: 2016-10-28T21:44:28Z
      DOI: 10.1016/j.plaphy.2016.10.011
      Issue No: Vol. 109 (2016)
       
  • Local and systemic hormonal responses in pepper leaves during compatible
           and incompatible pepper-tobamovirus interactions
    • Authors: Michał Dziurka; Anna Janeczko; Csilla Juhász; Gábor Gullner; Jana Oklestková; Ondrej Novák; Diana Saja; Andrzej Skoczowski; István Tóbiás; Balázs Barna
      Pages: 355 - 364
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Michał Dziurka, Anna Janeczko, Csilla Juhász, Gábor Gullner, Jana Oklestková, Ondrej Novák, Diana Saja, Andrzej Skoczowski, István Tóbiás, Balázs Barna
      Phytohormone levels and the expression of genes encoding key enzymes participating in hormone biosynthetic pathways were investigated in pepper leaves inoculated with two different tobamoviruses. Obuda pepper virus (ObPV) inoculation led to the development of hypersensitive reaction (incompatible interaction), while Pepper mild mottle virus (PMMoV) inoculation resulted in a systemic, compatible interaction. ObPV-inoculation markedly increased not only the levels of salicylic acid (SA) (73-fold) and jasmonic acid (8-fold) but also those of abscisic acid, indole-3-acetic acid, indole-3-butyric acid, cis-zeatin, cis-zeatin-9-riboside and trans-zeatin-9-riboside in the inoculated pepper leaves 3 days post inoculation. PMMoV infection increased only the contents of gibberellic acid and SA. Hormone contents did not change significantly after ObPV or PMMoV infection in non-infected upper leaves 20 days post inoculation. Concentrations of some brassinosteroids (BRs) and progesterone increased both in ObPV- and PMMoV inoculated leaves. ObPV inoculation markedly induced the expression of three phenylalanine ammonia-lyase (PAL) and a 1-aminocyclopropane-1-carboxylate oxidase (ACO) genes, while that of an isochorismate synthase (ICS) gene was not modified. PMMoV inoculation did not alter the expression of PAL and ICS genes but induced the transcript abundance of ACO although later than ObPV. Pre-treatment of pepper leaves with exogenous 24-epi-brassinolide (24-epi-BR) prior to ObPV-inoculation strongly mitigated the visible symptoms caused by ObPV. In addition, 24-epi-BR pre-treatment markedly altered the level of several hormones in pepper leaves following ObPV-inoculation. These data indicate that ObPV- and PMMoV-inoculations lead to intricate but well harmonized hormonal responses that are largely determined by the incompatible or compatible nature of plant-virus interactions.

      PubDate: 2016-11-03T21:49:28Z
      DOI: 10.1016/j.plaphy.2016.10.013
      Issue No: Vol. 109 (2016)
       
  • Chlorophyll a is a favorable substrate for Chlamydomonas Mg-dechelatase
           encoded by STAY-GREEN
    • Authors: Kaori Matsuda; Yousuke Shimoda; Ayumi Tanaka; Hisashi Ito
      Pages: 365 - 373
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Kaori Matsuda, Yousuke Shimoda, Ayumi Tanaka, Hisashi Ito
      Mg removal from chlorophyll by Mg-dechelatase is the first step of chlorophyll degradation. Recent studies showed that in Arabidopsis, Stay Green (SGR) encodes Mg-dechelatase. Though the Escherichia coli expression system is advantageous for investigating the properties of Mg-dechelatase, Arabidopsis Mg-dechelatase is not successfully expressed in E. coli. Chlamydomonas reinhardtii SGR (CrSGR) has a long, hydrophilic tail, suggesting that active CrSGR can be expressed in E. coli. After the incubation of chlorophyll a with CrSGR expressed in E. coli, pheophytin a accumulated, indicating that active CrSGR was expressed in E. coli. Substrate specificity of CrSGR against chlorophyll b and an intermediate molecule of the chlorophyll b degradation pathway was examined. CrSGR exhibited no activity against chlorophyll b and low activity against 7-hydroxymethyl chlorophyll a, consistent with the fact that chlorophyll b is degraded only after conversion to chlorophyll a. CrSGR exhibited low activity against divinyl chlorophyll a and chlorophyll a′, and no activity against chlorophyllide a, protochlorophyll a, chlorophyll c 2, and Zn-chlorophyll a. These observations indicate that chlorophyll a is the most favorable substrate for CrSGR. When CrSGR was expressed in Arabidopsis cells, the chlorophyll content decreased, further confirming that SGR has Mg-dechelating activity in chloroplasts.
      Graphical abstract image

      PubDate: 2016-11-03T21:49:28Z
      DOI: 10.1016/j.plaphy.2016.10.020
      Issue No: Vol. 109 (2016)
       
  • Effects of ambient solar UV radiation on grapevine leaf physiology and
           berry phenolic composition along one entire season under Mediterranean
           field conditions
    • Authors: María-Ángeles Del-Castillo-Alonso; María P. Diago; Rafael Tomás-Las-Heras; Laura Monforte; Gonzalo Soriano; Javier Martínez-Abaigar; Encarnación Núñez-Olivera
      Pages: 374 - 386
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): María-Ángeles Del-Castillo-Alonso, María P. Diago, Rafael Tomás-Las-Heras, Laura Monforte, Gonzalo Soriano, Javier Martínez-Abaigar, Encarnación Núñez-Olivera
      In the present study we assessed the effects of ambient solar UV exclusion on leaf physiology, and leaf and berry skin phenolic composition, of a major grapevine cultivar (Tempranillo) grown under typically Mediterranean field conditions over an entire season. In general, the effects of time were stronger than those of UV radiation. Ambient UV caused a little stressing effect (eustress) on leaf physiology, with decreasing net photosynthesis rates and stomatal conductances. However, it was not accompanied by alterations in Fv/Fm or photosynthetic pigments, and was partially counterbalanced by the UV-induced accumulation of protective flavonols. Consequently, Tempranillo leaves are notably adapted to current UV levels. The responses of berry skin phenolic compounds were diverse, moderate, and mostly transitory. At harvest, the clearest response in UV-exposed berries was again flavonol accumulation, together with a decrease in the flavonol hydroxylation level. Contrarily, responses of anthocyanins, flavanols, stilbenes and hydroxycinnamic derivatives were much more subtle or nonexistent. Kaempferols were the only compounds whose leaf and berry skin contents were correlated, which suggests a mostly different regulation of phenolic metabolism for each organ. Interestingly, the dose of biologically effective UV radiation (UVBE) was correlated with the leaf and berry skin contents of quercetins and kaempferols; relationships were linear except for the exponential relationship between UVBE dose and berry skin kaempferols. This opens management possibilities to modify kaempferol and quercetin contents in grapevine through UV manipulation.
      Graphical abstract image

      PubDate: 2016-11-03T21:49:28Z
      DOI: 10.1016/j.plaphy.2016.10.018
      Issue No: Vol. 109 (2016)
       
  • Tartary buckwheat FtMYB10 encodes an R2R3-MYB transcription factor that
           acts as a novel negative regulator of salt and drought response in
           transgenic Arabidopsis
    • Authors: Fei Gao; Huipeng Yao; Haixia Zhao; Jing Zhou; Xiaopeng Luo; Yunji Huang; Chenglei Li; Hui Chen; Qi wu
      Pages: 387 - 396
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Fei Gao, Huipeng Yao, Haixia Zhao, Jing Zhou, Xiaopeng Luo, Yunji Huang, Chenglei Li, Hui Chen, Qi wu
      Tartary buckwheat is a strongly abiotic, resistant coarse cereal, but its tolerance mechanisms for stress are largely unknown. MYB transcription factors play key roles in various physiological, biochemical and molecular responses, which can both positively and negatively regulate the stress tolerance of plants. In this study, we report that the expression of FtMYB10, a R2R3-MYB gene from Tartary buckwheat, was induced significantly by ABA and drought treatments. A seed germination test under ABA treatment indicated that transgenic lines were less sensitive to ABA. The overexpression of FtMYB10 in Arabidopsis reduced drought and salt tolerance. Further studies showed that the proline contents in the transgenic plants are markedly decreased associated with reduced expression of the P5CS1 gene under both normal and stress conditions. Furthermore, the expression of some stress-responsive genes, including DREB1/CBFs, RD29B, RD22, and several genes of the DRE/CRT class, decreased in response to FtMYB10 overexpression in Arabidopsis. These results suggest that FtMYB10 may play a key role in ABA signaling feedback regulation and act as a novel negative regulator of salt and drought stress tolerance in plants.

      PubDate: 2016-11-03T21:49:28Z
      DOI: 10.1016/j.plaphy.2016.10.022
      Issue No: Vol. 109 (2016)
       
  • Deciphering the ecophysiological traits involved during water stress
           acclimation and recovery of the threatened wild carnation, Dianthus
           inoxianus
    • Authors: Javier López-Jurado; Francisco Balao; Enrique Mateos-Naranjo
      Pages: 397 - 405
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Javier López-Jurado, Francisco Balao, Enrique Mateos-Naranjo
      Dianthus inoxianus is an endangered species endemic from a small littoral area in the SW Spain, with an unusual flowering season under the adverse conditions of dry Mediterranean summer. A greenhouse experiment was designed to assess the physiological traits involved in drought acclimation and recovery of 3-month-old plants. The evolution of plant water status, leaf gas exchange, chlorophyll fluorescence, photosynthetic pigments concentrations and a quantitative analysis of photosynthesis limitations were followed during water stress and re-watering. Our results indicated that the plant water status, Ψ w and RWC, only decreased at the end of the drought period (18th day), together with the net photosynthetic rate, A N. Photosynthetic impair was mainly caused by diffusional limitations (SL and MCL) of CO2, as indicated the joint and marked decrease of g s, g m and C i during drought period, while V c,max did not vary. After rewatering, leaf water status recovered faster than photosynthetic one, reaching control values on day 1 after recovery, while A N, g m and C i took 7 days. Additionally, g s showed the slowest recovery taking 15 days, but g s decrease was enough to keep Ψ w and RWC at constant values throughout the experiment. Results suggest a high tolerance and recovery of D. inoxianus from severe drought periods. This drought tolerance was also reflected in the stability of its photochemical apparatus and pigments concentrations, as indicated the constant values of F v/F m, Ф PSII and pigments concentrations through experimental period. However, prolonged drought events due to global climate change could negatively affect the physiological mechanisms of this species.

      PubDate: 2016-11-03T21:49:28Z
      DOI: 10.1016/j.plaphy.2016.10.023
      Issue No: Vol. 109 (2016)
       
  • Reactive oxygen species induced by cold stratification promote germination
           of Hedysarum scoparium seeds
    • Authors: Liqiang Su; Qinying Lan; Hugh W. Pritchard; Hua Xue; Xiaofeng Wang
      Pages: 406 - 415
      Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Liqiang Su, Qinying Lan, Hugh W. Pritchard, Hua Xue, Xiaofeng Wang
      Seed germination is comprehensively regulated by multiple intrinsic and extrinsic factors, and reactive oxygen species (ROS) are relatively new among these factors. However, the role and underlying mechanisms of ROS in germination regulation remain largely unknown. In this study, we initially found that cold stratification could promote germination and respiration of Hedysarum scoparium seeds, especially at low temperature. We then noted that a ROS environment change induced by hydrogen peroxide (H2O2) or methylviologen (MV) could similarly promote seed germination. On the other hand, the ROS scavenger N-acetyl-L-cysteine (NAC) suppressed germination of cold-stratified H. scoparium seeds, indicating a stimulatory role of ROS upon seed germination. An increased accumulation of O2 − was detected in embryonic axes of cold-stratified seeds, and stratification-induced ROS generation as well as progressive accumulation of ROS during germination was further confirmed at the cellular level by confocal microscopy. Moreover, protein carbonylation in cold-stratified seeds was enhanced during germination, which was reversed by NAC treatment. Finally, the relationship between ROS and abscisic acid (ABA) or gibberellin (GA) in germination regulation was investigated. ABA treatment significantly inhibited germination and reduced the H2O2 content in both cold-stratified and non-cold-stratified seeds. Furthermore, we found that cold stratification mediates the down-regulation of the ABA content and increase of GA, suggesting an interaction between ROS and ABA/GA. These results in H. scoparium shed new light on the positive role of ROS and their cross-talk between plant hormones in seed germination.

      PubDate: 2016-11-03T21:49:28Z
      DOI: 10.1016/j.plaphy.2016.10.025
      Issue No: Vol. 109 (2016)
       
 
 
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