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Journal Cover Plant Physiology and Biochemistry
  [SJR: 1.041]   [H-I: 70]   [9 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0981-9428
   Published by Elsevier Homepage  [2801 journals]
  • Aluminum induced metabolic responses in two tea cultivars
    • Abstract: Publication date: Available online 5 February 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Qingshan Xu, Yu Wang, Zhaotang Ding, Lubin Song, Yusheng Li, Dexin Ma, Yi Wang, Jiazhi Shen, Sisi Jia, Haiwei Sun, Hong Zhang
      Tea [Camellia sinensis (L.)], is an aluminum (Al3+) hyperaccumulator plant and grows well in acid soils. In the present study, roots of two tea cultivars, JHC and YS were treated with different concentrations of Al3+. After treatments, the root length, dry matter, root activity and chlorophyll content (SPAD value) of JHC had greater increase than that of YS. We also detected metabolic changes of two varieties using GC-MS method. Comparison between two cultivars indicated that shikimic pathway was more enhanced in YS roots by Al3+ with higher levels of catechine, quinic acid and shikimic acid. While, more active amino acid synthesis was found in JHC roots and JHC leaves remained the higher level contents of metabolites related to cysteine synthesis. The comparison also showed that a large amount of sugar alcohols were accumulated in roots of two varieties, whereas most of them were reduced in YS leaves. Other well-known ligands, such as phosphoric acid and malic acid were observed in two cultivars that showed significantly altered abundances under Al3+ treatments. The results indicated that Al3+ adaptation of two cultivars may be correlated with their differential metabolism of amino acids, sugars and shikimic acids.


      PubDate: 2016-02-09T16:34:05Z
       
  • Transcriptome-wide identification and expression analysis of chrysanthemum
           SBP-like transcription factors
    • Abstract: Publication date: Available online 8 February 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Aiping Song, Tianwei Gao, Dan Wu, Jingjing Xin, Sumei Chen, Zhiyong Guan, Haibin Wang, Lili Jin, Fadi Chen
      SQUAMOSA promoter-binding protein (SBP) transcription factors are known to function in a number of processes in plants. Here, we have characterized twelve SBP-like (SPL) genes in the important ornamental species chrysanthemum (Chrysanthemum morifolium). A total of twelve distinct sequences were isolated and amplified based on transcriptomic sequences. Phylogenetic analysis identified two pairs of orthologous proteins for Arabidopsis and chrysanthemum and two pairs of paralogous proteins in chrysanthemum. Conserved motifs in the SPL proteins shared by Arabidopsis and chrysanthemum were scanned using MEME. A bioinformatics analysis revealed that six of these genes contained a miR156 target site, while five CmSPLs were targeted by miR157. Moreover, we used 5’ RLM-RACE to map the cleavage sites in CmSPL2 and CmSPL3. The expression of these twelve genes in response to a variety of phytohormone treatments and abiotic stresses was characterized. This work improves our understanding of the various functions of SPL gene family members in the stress response.


      PubDate: 2016-02-09T16:34:05Z
       
  • Effect of post-silking drought on nitrogen partitioning and gene
           expression patterns of glutamine synthetase and asparagine synthetase in
           two maize (Zea mays L.) varieties
    • Abstract: Publication date: Available online 8 February 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Yajun Li, Meiling Wang, Fengxia Zhang, Yadong Xu, Xiaohong Chen, Xiaoliang Qin, Xiaoxia Wen
      Glutamine synthetase (GS) and asparagine synthetase (AS) are proposed to have important function in plant nitrogen (N) remobilization, but their roles under drought stress are not well defined. In this study, the expression dynamics of GS and AS genes were analyzed in two maize varieties (ZD958 and NH101) in relation to post-silking drought stress induced nitrogen partitioning. ZD958 was a ‘stay-green’ variety with 5% nitrogen harvest index (NHI) lower than NH101. From silking to maturity, the amount of nitrogen remobilized from ear-leaves in ZD958 was evidently lower than NH101, and post-silking drought stress increased the nitrogen remobilization for both varieties. In ear-leaves, the expression of ZmGln1-3 was enhanced under drought stress. Three AS genes (ZmAS1, ZmAS2 and ZmAS3) were differentially regulated by post-silking drought treatment, of which the expression of ZmAS3 was stimulated at late stage of leaf senescence. In NH101, the expression level of ZmAS3 was markedly higher than that in ZD958. In developing grains, there were no significant differences in expression patterns of GS and AS genes between well water and drought treated plants. Drought stress altered maize N partitioning at the whole-plant level, and the up-regulation of GS and AS genes may contribute to the higher leaf nitrogen remobilization when exposed to drought treatments.


      PubDate: 2016-02-09T16:34:05Z
       
  • Changes in the protective mechanism of photosystem II and molecular
           regulation in response to high temperature stress in grapevines
    • Abstract: Publication date: April 2016
      Source:Plant Physiology and Biochemistry, Volume 101
      Author(s): Qian Zha, Xiaojun Xi, Aili Jiang, Shiping Wang, Yihua Tian
      The response to high temperature stress, which influences the growth and development of grapes, varies between laboratory conditions and ambient growth conditions, and is poorly understood. In the present study, we investigated the effects of high temperature on grapevines (Vitis vinifera L. × Vitis labrusca L.) grown under artificial and ambient conditions. A temperature of 35 °C did not alter Photosystem II (PS II) activity and the expression of some heat-shock protein (HSPs) genes. These changes were, however, observed at 45 °C under artificial conditions, as well as when the ambient natural temperature was greater than 40 °C. Interestingly, these changes corresponded to shifts in PS II activity and HSPs expression. The protective mechanism of PS II was induced by temperatures greater than 40 °C. These data indicating that the expression of HSFA2, GLOS1 and some heat-shock protein (sHSPs) genes were more sensitive to the heat stress. Unlike the Kyoho grapevines, the Jumeigui grapevines showed rapid and dramatically deterioration in PS II activity and the expression of some heat response genes and HSP21, indicating that the Jumeigui grapevines could not counter the heat stress. These were some differences in PSII activity and the expression of heat response genes between the two cultivated conditions could be attributed to other environmental factors, inherent plant vigor, and the adaptation mechanism.


      PubDate: 2016-02-09T16:34:05Z
       
  • Characterization of wheat miRNAs and their target genes responsive to
           cadmium stress
    • Abstract: Publication date: April 2016
      Source:Plant Physiology and Biochemistry, Volume 101
      Author(s): ZongBo Qiu, BenZhai Hai, JunLi Guo, YongFang Li, Liang Zhang
      A increasing number of microRNAs have been shown to play important regulatory roles in plant responses to various metal stresses. However, little information about miRNAs especially miRNAs responsive to cadmium (Cd) stress is available in wheat. To investigate the role of miRNAs in responses to Cd stress, wheat seedlings were subjected to 250 μM Cd solution for 6, 12, 24 and 48 h, and analyses of morphological and physiological changes as well as the expression of five miRNAs and their corresponding targets were carried out. Our results demonstrated that miRNAs and their targets were differentially expressed in leaves and roots of wheat seedlings exposed to Cd stress. Furthermore, miR398 may involve in oxidative stress tolerance by regulating its target CSD to participate in Cd stress. Among ten miRNA-target pairs studied, nine pairs showed complex regulation relationship in leaves and roots of wheat seedlings exposed to Cd stress. These findings suggested that miRNAs are involved in the mediation of Cd stress signaling responses in wheat. The characterization of the miRNAs and the associated targets in responses to Cd exposure provides a framework for understanding the molecular mechanism of heavy metal tolerance in plants.


      PubDate: 2016-02-09T16:34:05Z
       
  • Volatiles released by endophytic Pseudomonas fluorescens promoting the
           growth and volatile oil accumulation in Atractylodes lancea
    • Abstract: Publication date: Available online 2 February 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Jia-Yu Zhou, Xia Li, Jiao-Yan Zheng, Chuan-Chao Dai
      Atractylodes lancea is a well-known, but endangered, Chinese medicinal plant whose volatile oils are its main active components. As the volatile oil content in cultivated A. lancea is much lower than that in the wild herb, the application of microbes or related elicitors to promote growth and volatile oil accumulation in the cultivated herb is an important area of research. This study demonstrates that the endophytic bacterium Pseudomonas fluorescens ALEB7B isolated from the geo-authentic A. lancea can release several nitrogenous volatiles, such as formamide and N,N-dimethyl-formamide, which significantly promote the growth of non-infected A. lancea. Moreover, the main bacterial volatile benzaldehyde significantly promotes volatile oil accumulation in non-infected A. lancea via activating plant defense responses. Notably, the bacterial nitrogenous volatiles cannot be detected in the A. lancea - P. fluorescens symbiont while the benzaldehyde can be detected, indicating the nitrogenous volatiles or their precursors may have been consumed by the host plant. This study firstly demonstrates that the interaction between plant and endophytic bacterium is not limited to the commonly known physical contact, extending the ecological functions of endophyte in the phytosphere and deepening the understandings about the symbiotic interaction.


      PubDate: 2016-02-09T16:34:05Z
       
  • Salt acclimation processes in wheat
    • Abstract: Publication date: April 2016
      Source:Plant Physiology and Biochemistry, Volume 101
      Author(s): Tibor Janda, Éva Darko, Sami Shehata, Viktória Kovács, Magda Pál, Gabriella Szalai
      Young wheat plants (Triticum aestivum L. cv. Mv Béres) were exposed to 0 or 25 mM NaCl for 11 days (salt acclimation). Thereafter the plants were irrigated with 500 mM NaCl for 5 days (salt stress). Irrigating the plants with a low concentration of NaCl successfully led to a reduction in chlorotic symptoms and in the impairment of the photosynthetic processes when the plants were exposed to subsequent high-dose salt treatment. After exposure to a high concentration of NaCl there was no difference in leaf Na content between the salt-acclimated and non-acclimated plants, indicating that salt acclimation did not significantly modify Na transport to the shoots. While the polyamine level was lower in salt-treated plants than in the control, salt acclimation led to increased osmotic potential in the leaves. Similarly, the activities of certain antioxidant enzymes, namely glutathione reductase, catalase and ascorbate peroxidase, were significantly higher in salt-acclimated plants. The results also suggest that while SOS1, SOS2 or NHX2 do not play a decisive role in the salt acclimation processes in young wheat plants; another stress-related gene, WALI6, may contribute to the success of the salt acclimation processes. The present study suggested that the responses of wheat plants to acclimation with low level of salt and to treatment with high doses of salt may be fundamentally different.


      PubDate: 2016-02-09T16:34:05Z
       
  • Editorial Board
    • Abstract: Publication date: February 2016
      Source:Plant Physiology and Biochemistry, Volume 99




      PubDate: 2016-02-09T16:34:05Z
       
  • Characterization of a multifunctional caffeoyl-CoA methyltransferase
           activated in grape berries upon drought stress
    • Abstract: Publication date: Available online 26 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Debora Giordano, Sofia Provenzano, Alessandra Ferrandino, Marco Vitali, Chiara Pagliarani, Federica Roman, Francesca Cardinale, Simone D. Castellarin, Andrea Schubert
      Drought stress affects anthocyanin accumulation and modification in vegetative and reproductive plant tissues. Anthocyanins are the most abundant flavonoids in grape (Vitis vinifera L.) coloured berry genotypes and are essential markers of grape winemaking quality. They are mostly mono- and di-methylated, such modifications increase their stability and improve berry quality for winemaking. Anthocyanin methylation in grape berries is induced by drought stress. A few caffeoyl-CoA O-methyltransferases (CCoAOMTs) active on anthocyanins have been described in grape. However, no drought-activated O-methyltransferases have been described in grape berries yet. In this study, we characterized VvCCoAOMT, a grapevine gene known to induce methylation of CoA esters in cultured grape cells. Transcript accumulation of VvCCoAOMT was detected in berry skins, and increased during berry ripening on the plant, and in cultured berries treated with ABA, concomitantly with accumulation of methylated anthocyanins, suggesting that anthocyanins may be substrates of this enzyme. Contrary as previously observed in cell cultures, biotic stress (Botrytis cinerea inoculation) did not affect VvCCoAOMT gene expression in leaves or berries, while drought stress increased VvCCoAOMT transcript in berries. The recombinant VvCCoAOMT protein showed in vitro methylating activity on cyanidin 3-O-glucoside. We conclude that VvCCoAOMT is a multifunctional O-methyltransferase that may contribute to anthocyanin methylation activity in grape berries, in particular under drought stress conditions.


      PubDate: 2016-01-30T16:01:58Z
       
  • Molecular Cloning and Characterization of a novel Bi-functional
           α-Amylase/Subtilisin Inhibitor from Hevea brasiliensis
    • Abstract: Publication date: Available online 26 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Orawan Bunyatang, Nion Chirapongsatonkul, Phuwadol Bangrak, Robert Henry, Nunta Churngchow
      A novel cDNA encoding a bi-functional α-amylase/subtilisin inhibitor (HbASI) was isolated from rubber (Hevea brasiliensis) leaves cultivar RRIM600. The HbASI had strong homology with the soybean trypsin inhibitor (Kunitz) family of protease inhibitors. Its putative amino acid sequence was similar to that of the α-amylase/subtilisin inhibitor from Ricinus communis (72% identity). Genomic sequencing indicated that the HbASI gene contained no introns. The messenger RNA of HbASI was detected in leaf, hypocotyl and root. The recombinant HbASI expressed extracellularly in Pichia pastoris exhibited inhibitory activity against α-amylase from Aspergillus oryzae, trypsin and subtilisin A. The HbASI gene was induced in the rubber leaves infected with a rubber tree pathogen, Phytophthora palmivora. It was also enhanced by salicylic acid (SA) treatment and mechanical wounding. In addition, the biological activity of the HbASI protein involving in the plant defence responses was also investigated. The HbASI at a concentration of 0.16 mg.mL-1 could inhibit the mycelium growth of P. palmivora. These data suggested that the HbASI protein might play a crucial role in defence against pathogen of rubber trees.


      PubDate: 2016-01-30T16:01:58Z
       
  • Diacylglycerol pyrophosphate binds and inhibits the
           glyceraldehyde-3-phosphate dehydrogenase in barley aleurone
    • Abstract: Publication date: Available online 27 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Paula Luján Astorquiza, Javier Usorach, Graciela Racagni, Ana Laura Villasuso
      The aleurona cell is a model that allows the study of the antagonistic effect of gibberellic acid (GA) and abscisic acid (ABA). Previous results of our laboratory demonstrated the involvement of phospholipids during the response to ABA and GA. ABA modulates the levels of diacylglycerol, phosphatidic acid and diacylglycerol pyrophosphate (DAG, PA, DGPP) through the activities of phosphatidate phosphatases, phospholipase D, diacylglycerol kinase and phosphatidate kinase (PAP, PLD, DGK and PAK). PA and DGPP are key phospholipids in the response to ABA, since both are capable of modifying the hydrolitic activity of the aleurona. Nevertheless, little is known about the mechanism of action of these phospholipids during the ABA signal. DGPP is an anionic phospholipid with a pyrophosphate group attached to diacylglycerol. The ionization of the pyrophosphate group may be important to allow electrostatic interactions between DGPP and proteins. To understand how DGPP mediates cell functions in barley aleurone, we used a DGPP affinity membrane assay to isolate DGPP-binding proteins from Hordeum vulgare, followed by mass spectrometric sequencing. A cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) was identified for being bound to DGPP. To validate our method, the relatively abundant GAPDH was characterized with respect to its lipid-binding properties, by fat western blot. GAPDH antibody interacts with proteins that only bind to DGPP and PA. We also observed that ABA treatment increased GAPDH abundance and enzyme activity. The presence of phospholipids during GAPDH reaction modulated the GAPDH activity in ABA treated aleurone. These data suggest that DGPP binds to GAPDH and this DGPP and GAPDH interaction provides new evidences in the study of DGPP-mediated ABA responses in barley aleurone.


      PubDate: 2016-01-30T16:01:58Z
       
  • Effects of salinity on the photosynthetic apparatus of two Paulownia lines
    • Abstract: Publication date: Available online 28 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Martin Stefanov, Ekaterina Yotsova, Georgi Rashkov, Katya Ivanova, Yuliana Markovska, Emilia L. Аpostolova
      The effects of soil salinity on the functional activity of photosynthetic apparatus and pigment composition of two Paulownia lines (Paulownia tomentosa x fortunei and Paulownia elongata x elongata) were investigated. PAM chlorophyll fluorescence measurements revealed that salinity leads to: (i) an increase of the photochemical quenching coefficient (qP) and the linear electron transport rate (ETR) in both lines of Paulownia, while the maximum quantum yield of the primary photochemistry of PSII in the dark adapted state (Fv/Fm) was unaffected; (ii) improved the efficiency of the photochemical energy conversion (ФPSII); (iii) an impact on the chlorophyll fluorescence decrease ratio (RFd), which correlates to the net CO2 assimilation rate; (iv) an impact on QA - reoxidation. The analysis of the kinetics of P700 + reduction upon turning off far-red irradiation revealed that salinization lead to a delay of the cyclic electron transport around PSI in both studied lines as the effect on this process is more pronounced in Paulownia tomentosa x fortunei than in (in comparison with) Paulownia elongata x elongata. The present experimental results suggested high salt tolerance of the studied lines Paulownia, but Paulownia tomentosa x fortunei is more tolerant to salinity than Paulownia elongata x elongata. Molecular mechanisms involved in the Paulownia response to the soil salinity are discussed.
      Graphical abstract image

      PubDate: 2016-01-30T16:01:58Z
       
  • Melatonin-induced CBF/DREB1s are essential for diurnal change of disease
           resistance and CCA1 expression in Arabidopsis
    • Abstract: Publication date: Available online 22 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Haitao Shi, Yunxie Wei, Chaozu He
      Melatonin (N-acetyl-5-methoxytryptamine) is an important regulator of circadian rhythms and immunity in animals. However, the diurnal changes of endogenous melatonin and melatonin-mediated diurnal change of downstream responses remain unclear in Arabidopsis. Using the publicly available microarray data, we found that the transcript levels of two melatonin synthesis genes (serotonin N-acetyltransferase (SNAT) and caffeate O-methyltransferase (COMT)) and endogenous melatonin level were regulated by diurnal cycles, with different magnitudes of change. Moreover, the transcripts of C-repeat-binding factors (CBFs)/Drought response element Binding 1 factors (DREB1s) were co-regulated by exogenous melatonin and diurnal changes, indicating the possible correlation among clock, endogenous melatonin level and AtCBFs expressions. Interestingly, diurnal change of plant immunity against Pst DC3000 and CIRCADIANCLOCK ASSOCIATED 1 (CCA1) expression were largely lost in AtCBFs knockdown line-amiR-1. Taken together, this study identifies the molecular pathway underlying the diurnal changes of immunity in Arabidopsis. Notably, the diurnal changes of endogenous melatonin may regulate corresponding changes of AtCBF/DREB1s expression and their underlying diurnal cycle of plant immunity and AtCCA1.


      PubDate: 2016-01-24T15:24:17Z
       
  • Salares versus coastal ecotypes of quinoa: salinity responses in Chilean
           landraces from contrasting habitats
    • Abstract: Publication date: Available online 22 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Karina B. Ruiz, Iris Aloisi, Stefano Del Duca, Valentina Canelo, Patrizia Torrigiani, Herman Silva, Stefania Biondi
      Quinoa (Chenopodium quinoa Willd.) is a highly salt-tolerant species subdivided into five ecotypes and exhibiting broad intra-specific differences in tolerance levels. In a greenhouse study, Chilean landraces belonging either to the salares (R49) or coastal lowlands (VI-1, Villarrica) ecotype with contrasting agro-ecological origins were investigated for their responses to high salinity. The effects of two levels of salinity, 100 (T1) and 300 (T2) mM NaCl, on plant growth and on some physiological parameters were measured. Leaf and root Na+ accumulation differed among landraces. T2 reduced growth and seed yield in all landraces with maximum inhibition relative to controls in R49. Salinity negatively affected chlorophyll and total polyphenol content (TPC) in VI-1 and Villarrica but not R49. Germination on saline or control media of seeds harvested from plants treated or not with NaCl was sometimes different; the best performing landrace was R49 insofar as 45-65% of seeds germinated on 500 mM NaCl-containing medium. In all landraces, average seedling root length declined strongly with increasing NaCl concentration, but roots of R49 were significantly longer than those of VI-1 and Villarrica up to 300 mM NaCl. Salt caused increases in seed TPC relative to controls, but radical scavenging capacity was higher only in seeds from T2 plants of R49. Total SDS-extractable seed proteins were resolved into distinct bands (10-70 kDa) with some evident differences between landraces. Salt-induced changes in protein patterns were landrace-specific. The responses to salinity of the salares landrace are discussed in relation to its better adaptation to an extreme environment.


      PubDate: 2016-01-24T15:24:17Z
       
  • Investigation of the effect of genotype and agronomic conditions on
           metabolomic profiles of selected strawberry cultivars with different
           sensitivity to environmental stress
    • Abstract: Publication date: Available online 22 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Ikram Akhatou, Raúl González-Domínguez, Ángeles Fernández-Recamales
      Strawberry is one of the most economically important and widely cultivated fruit crops across the world, so that there is a growing need to develop new analytical methodologies for the authentication of variety and origin, as well as the assessment of agricultural and processing practices.In this work, an untargeted metabolomic strategy based on gas chromatography mass spectrometry (GC-MS) combined with multivariate statistical techniques was used for the first time to characterize the primary metabolome of different strawberry cultivars and to study metabolite alterations in response to multipleagronomic conditions. For this purpose, we investigated three varieties of strawberries with different sensitivity to environmental stress (Camarosa, Festival and Palomar), cultivatedin soilless systemsusing various electrical conductivities, types of coverage and substrates. Metabolomic analysis revealed significant alterations in primary metabolites between the three strawberry cultivars grown under different crop conditions, including sugars (fructose, glucose), organic acids (malic acid, citric acid) and amino acids (alanine, threonine, aspartic acid), among others. Therefore, it could be concluded that GC-MS based metabolomics is a suitable tool to differentiate strawberry cultivars and characterize metabolomic changes associated with environmental and agronomic conditions.
      Graphical abstract image

      PubDate: 2016-01-24T15:24:17Z
       
  • Adaptive flexibility of enzymatic antioxidants SOD, APX and CAT to high
           light stress: the clonal perennial monocot Iris pumila as a study case
    • Abstract: Publication date: Available online 19 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Ana Vuleta, Sanja Manitašević Jovanović, Branka Tucić
      High solar radiation has been recognized as one of the main causes of the overproduction of reactive oxygen species (ROS) and oxidative stress in plants. To remove the excess of ROS, plants use different antioxidants and tune their activity and/or isoform number as required for given light conditions. In this study, the adaptiveness of light-induced variation in the activities and isoform patterns of key enzymatic antioxidants SOD, APX and CAT was tested in leaves of Iris pumila clonal plants from two natural populations inhabiting a sun exposed dune site and a forest understory, using a reciprocal-transplant experiment. At the exposed habitat, the mean enzymatic activity of total SODs was significantly greater than that in the shaded one, while the amount of the mitochondrial MnSOD was notably higher compared to the plastidic Cu/ZnSOD. However, the number of Cu/ZnSOD isoforms was greater in the forest understory relative to the exposed site (three vs. two, respectively). An inverse relationship recorded between the quantities of MnSOD and Cu/ZnSOD in alternative light habitats might indicate that the two enzymes compensate each other in maintaining intracellular ROS and redox balance. The adaptive population differentiation in APX activity was exclusively recorded in the open habitat, which indicated that the synergistic effect of high light and temperature stress could be the principal selective factor, rather than high light alone. The enzymatic activity of CAT was similar between the two populations, implicating APX as the primary H2O2 scavenger in the I. pumila leaves exposed to high light intensity.


      PubDate: 2016-01-20T15:13:11Z
       
  • Transcriptome analysis of the Taxodium ‘Zhongshanshan 405’
           roots in response to salinity stress
    • Abstract: Publication date: Available online 18 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Chaoguang Yu, Sheng Xu, Yunlong Yin
      Taxodium ‘Zhongshanshan’ is an interspecies hybrid of T. distichum and T. mucronatum, and has been widely planted in southeastern China. It has great ecological and economic potential. However, the scant genomic resources in genus Taxodium have greatly hindered further exploration of its underlying salinity-tolerance mechanism. To understand the genetic basis of its salt tolerance, we analyzed the transcriptomes of Taxodium ‘Zhongshanshan 405’ roots in response to salinity stress. RNA-seq was used to analyze transcriptome changes of ‘Zhongshanshan 405’ clone root treated with NaCl stress. After de novo assembly, 70,312 unigenes were achieved, and 41,059 of them were annotated. 9,038 differentially expressed genes (DEGs) were identified among the treatments, and 7,959 DEGs were found between salt-stressed roots and control, with 489 up-regulated and 570 down-regulated shared by all of the treatments. Genes related to transport, signal transductions as well as undescribed transcripts were among those DEGs in response to salt stress. Gene ontology classification analysis revealed that salt stress-related categories including ‘oxidoreductase activity’, ‘metal ion binding’, and ‘membrane’ were highly enriched among these DEGs. Moreover, the gene expression pattern of 12 unigenes revealed by quantitative real-time polymerase chain reaction (qRT-PCR) confirmed the RNA-Seq data. Our study not only provided the large-scale assessment of genomic resources of Taxodium but also guidelines for probing the molecular mechanism underlying ‘Zhongshanshan’ salt tolerance.


      PubDate: 2016-01-20T15:13:11Z
       
  • Reduction of the plastidial phosphorylase in potato (Solanum tuberosum L.)
           reveals impact on storage starch structure during growth at low
           temperature
    • Abstract: Publication date: Available online 20 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Tom Orawetz, Irina Malinova, Slawomir Orzechowski, Joerg Fettke
      Tubers of potato (Solanum tuberosum L.), one of the most important crops, are a prominent example for an efficient production of storage starch. Nevertheless, the synthesis of this storage starch is not completely understood. The plastidial phosphorylase (Pho1; EC 2.4.1.1) catalyzes the reversible transfer of glucosyl residues from glucose-1-phosphate to the non-reducing end of α-glucans with the release of orthophosphate. Thus, the enzyme is in principle able to act during starch synthesis. However, so far under normal growth conditions no alterations in tuber starch metabolism were observed. Based on analyses of other species and also from in vitro experiments with potato tuber slices it was supposed, that Pho1 has a stronger impact on starch metabolism, when plants grow under low temperature conditions. Therefore, we analyze the starch content, granule size, as well as the internal structure of starch granules isolated from potato plants grown under low temperatures. Besides wild type, transgenic potato plants with a strong reduction in the Pho1 activity were analyzed. No significant alterations in starch content and granule size were detected. In contrast, when plants were cultivated at low temperatures the chain length distributions of the starch granules were altered. Thus, the granules contained more short glucan chains. That was not observed in the transgenic plants, revealing that Pho1 in wild type is involved in the formation of the short glucan chains, at least at low temperatures.


      PubDate: 2016-01-20T15:13:11Z
       
  • Transgenic poplar expressing codA exhibits enhanced growth and abiotic
           stress tolerance
    • Abstract: Publication date: Available online 12 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Qingbo Ke, Zhi Wang, Chang Yoon Ji, Jae Cheol Jeong, Haeng-Soon Lee, Hongbing Li, Bingcheng Xu, Xiping Deng, Sang-Soo Kwak
      Glycine betaine (GB), a compatible solute, effectively stabilizes the structure and function of macromolecules and enhances abiotic stress tolerance in plants. We generated transgenic poplar plants (Populus alba × P. glandulosa) expressing a bacterial choline oxidase (codA) gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SC plants). Among the 13 SC plants generated, three lines (SC4, SC14 and SC21) were established based on codA transcript levels, tolerance to methyl viologen-mediated oxidative stress and Southern blot analysis. Growth was better in SC plants than in non-transgenic (NT) plants, which was related to elevated transcript levels of auxin-response genes. SC plants accumulated higher levels of GB under oxidative stress compared to the NT plants. In addition, SC plants exhibited increased tolerance to drought and salt stress, which was associated with increased efficiency of photosystem II activity. Finally, SC plants maintained lower levels of ion leakage and reactive oxygen species under cold stress compared to the NT plants. These observations suggest that SC plants might be useful for reforestation on global marginal lands, including desertification and reclaimed areas.


      PubDate: 2016-01-16T14:59:10Z
       
  • The contribution of stored malate and citrate to the substrate
           requirements of metabolism of ripening peach (Prunus persica L. Batsch)
           flesh is negligible. Implications for the occurrence of
           phosphoenolpyruvate carboxykinase and gluconeogenesis
    • Abstract: Publication date: Available online 14 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Franco Famiani, Daniela Farinelli, Stefano Moscatello, Alberto Battistelli, Richard C. Leegood, Robert P. Walker
      The first aim of this study was to determine the contribution of stored malate and citrate to the substrate requirements of metabolism in the ripening flesh of the peach (Prunus persica L. Batsch) cultivar Adriatica. In the flesh, stored malate accumulated before ripening could contribute little or nothing to the net substrate requirements of metabolism. This was because there was synthesis and not dissimilation of malate throughout ripening. Stored citrate could contribute a very small amount (about 5.8%) of the substrate required by metabolism when the whole ripening period was considered, and a maximum of about 7.5% over the latter part of ripening. The second aim of this study was to investigate why phosphoenolpyruvate carboxykinase (PEPCK) an enzyme utilised in gluconeogenesis from malate and citrate is present in peach flesh. The occurrence and localisation of enzymes utilised in the metabolism of malate, citrate and amino acids were determined in peach flesh throughout its development. Phosphoenolpyruvate carboxylase (essential for the synthesis of malate and citrate) was present in the same cells and at the same time as PEPCK and NADP-malic enzyme (both utilised in the dissimilation of malate and citrate). A hypothesis is presented to explain the presence of these enzymes and to account for the likely occurrence of gluconeogenesis.


      PubDate: 2016-01-16T14:59:10Z
       
  • Effect of polyamines on the grain filling of wheat under drought stress
    • Abstract: Publication date: Available online 14 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Yang Liu, Haiyan Liang, Xiaokang Lv, Didi Liu, Xiaoxia Wen, Yuncheng Liao
      Drought inhibits wheat grain filling. Polyamines (PAs) are closely associated with plant resistance due to drought and grain filling of cereals. However, little is known about the effect of PAs on the grain filling of wheat under drought stress. This study investigated whether and how PAs are involved in regulating wheat grain filling under drought stress. Two wheat genotypes differing in drought resistance were used, and endogenous PA levels were measured during grain filling under different water treatments. Additionally, external PAs were used, and the variation of hormone levels in grains was measured during grain filling under drought stress. The results indicated that spermidine (Spd) and spermine (Spm) relieve the inhibition caused by drought stress, and putrescine (Put) has the opposite effect. The higher activities of S-adenosylmethionine decarboxylase and Spd synthase in grains promotes the synthetic route from Put to Spd and Spm and notably increases the free Spd and Spm concentrations in grains, which promotes grain filling and drought resistance in wheat. The effect of PA on the grain filling of wheat under drought stress was closely related to the endogenous ethylene (ETH), zeatin (Z) + zeatin riboside (ZR) and abscisic acid (ABA). Spd and Spm significantly increased the Z+ZR and ABA concentrations and decreased the ETH evolution rate in grains, which promoted wheat grain filling under drought. Put significantly increased the ETH evolution rate, which led to excessive ABA accumulation in grains, subsequently aggravating the inhibition of drought on wheat grain filling. This means that the interaction of hormones, rather than the action of a single hormone, was involved in the regulation of wheat grain filling under drought.


      PubDate: 2016-01-16T14:59:10Z
       
  • Chloride stress triggers maturation and negatively affects the postharvest
           quality of persimmon fruit. Involvement of calyx ethylene production
    • Abstract: Publication date: Available online 14 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Cristina Besada, Rebeca Gil, Luis Bonet, Ana Quiñones, Diego Intrigliolo, Alejandra Salvador
      In recent years many hectares planted with persimmon trees in E Spain have been diagnosed with chloride toxicity. An effect of this abiotic stress on fruit quality has been reported in different crops. However, the impact of chloride stress on persimmon fruit quality is unknown. The harvest and postharvest quality of persimmons harvested from trees that manifest different intensities of chloride toxicity foliar symptoms was evaluated herein. Our results revealed that fruits from trees under chloride stress conditions underwent chloride accumulation in the calyx, which was more marked the greater the salt stress intensity trees were exposed to. Increased chloride concentrations in the calyx stimulated ethylene production in this tissue. In the fruits affected by slight and moderate chloride stress, calyx ethylene production accelerated the maturity process, as reflected by increased fruit colour and diminished fruit firmness. In the fruits under severe chloride stress, the high ethylene levels in the calyx triggered autocatalytic ethylene production in other fruit tissues, which led fruit maturity to drastically advance. In these fruits effectiveness of CO2 deastringency treatment was not complete and fruit softening enhanced during the postharvest period. Moreover, chloride stress conditions had a marked effect on reducing fruit weight, even in slightly stressed trees.
      Graphical abstract image

      PubDate: 2016-01-16T14:59:10Z
       
  • Downregulation of a barley (Hordeum vulgare) leucine-rich repeat,
           non-arginine-aspartate receptor-like protein kinase reduces expression of
           numerous genes involved in plant pathogen defense
    • Abstract: Publication date: Available online 15 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): David L. Parrott, Li Huang, Andreas M. Fischer
      Pattern recognition receptors represent a first line of plant defense against pathogens. Comparing the flag leaf transcriptomes of barley (Hordeum vulgare L.) near-isogenic lines varying in the allelic state of a locus controlling senescence, we have previously identified a leucine-rich repeat receptor-like protein kinase gene (LRR-RLK; GenBank accession: AK249842), which was strongly upregulated in leaves of early-as compared to late-senescing germplasm. Bioinformatic analysis indicated that this gene codes for a subfamily XII, non-arginine-aspartate (non-RD) LRR-RLK. Virus-induced gene silencing resulted in a two-fold reduction of transcript levels as compared to controls. Transcriptomic comparison of leaves from untreated plants, from plants treated with virus only without any plant sequences (referred to as 'empty virus' control), and from plants in which AK249842 expression was knocked down identified numerous genes involved in pathogen defense. These genes were strongly induced in 'empty virus' as compared to untreated controls, but their expression was significantly reduced (again compared to 'empty virus' controls) when AK249842 was knocked down, indicating that their expression partially depends on the LRR-RLK investigated here. Expression analysis, using datasets from BarleyBase/PLEXdb, demonstrated that AK249842 transcript levels are heavily influenced by the allelic state of the well-characterized mildew resistance a (Mla) locus, and that the gene is induced after powdery mildew and stem rust infection. Together, our data suggest that AK249842 is a barley pattern recognition receptor with a tentative role in defense against fungal pathogens, setting the stage for its full functional characterization.


      PubDate: 2016-01-16T14:59:10Z
       
  • Comparative photosynthetic and metabolic analyses reveal mechanism of
           improved cold stress tolerance in bermudagrass by exogenous melatonin
    • Abstract: Publication date: Available online 15 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Zhengrong Hu, Jibiao Fan, Yan Xie, Erick Amombo, Ao Liu, Margaret Gitau Mukami, A.B.M. Khaldun, Liang Chen, Jinmin Fu
      Melatonin (N-acetyl-5-methoxytryptamine) has been reported to participate in plant development and abiotic stress responses. The main objective of this study was to investigate the role of melatonin in the cold-sensitive (S) and the cold-tolerant (T) bermudagrass genotypes’ response to cold stress. The genotypes were treated with 100 μM melatonin and exposed to 4°C temperature for 3 days. In both genotypes, cold stress increased the endogenous melatonin levels, and more prominently in T than S. Physiological responses indicated that exogenous melatonin triggered antioxidant activities in both genotypes, while it alleviated cell damage in the T genotype response to cold stress. Melatonin treatment under cold stress increased fluorescence curve levels for both genotypes, and higher in T than S genotypes. In both genotypes, the alterations in photosynthetic fluorescence parameters after melatonin treatment highlighted the participation of melatonin in improving photosystem response to cold stress, particularly for the cold-tolerant genotype. The metabolic analyses revealed the alterations of 44 cold-responsive metabolites in the two genotypes, mainly including carbohydrates, organic acids and amino acids. After exogenous melatonin treatment under cold condition, there was high accumulation of metabolites in the cold-tolerant regimes than their cold-sensitive counterparts. Collectively, the present study revealed differential modulations of melatonin between the cold-sensitive and the cold-tolerant genotypes in response to cold stress. This was mainly by impacting antioxidant system, photosystem II, as well as metabolic homeostasis.


      PubDate: 2016-01-16T14:59:10Z
       
  • Biocontrol Potential of Trichoderma harzianum isolate T-aloe against
           Sclerotinia sclerotiorum in soybean
    • Abstract: Publication date: Available online 8 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Fuli Zhang, Honglian Ge, Fan Zhang, Ning Guo, Yucheng Wang, Long Chen, Xiue Ji, Chengwei Li
      Sclerotinia stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary is a major disease of soybean (Glycine max (L.) Merr.). At present, we revealed the three-way interaction between Trichoderma harzianum T-aloe, pathogen S. sclerotiorum and soybean plants in order to demonstrate biocontrol mechanism and evaluate biocontrol potential of T-aloe against S. sclerotiorum in soybean. In our experiments, T-aloe inhibited the growth of S. sclerotiorum with an efficiency of 56.3% in dual culture tests. T-aloe hyphae grew in parallel or intertwined with S. sclerotiorum hyphae and produced hooked contact branches, indicating mycoparasitism. Plate tests showed that T-aloe culture filtrate inhibited S. sclerotiorum growth with an inhibition efficiency of 51.2% and sclerotia production. T-aloe pretreatment showed growth-promoting effect on soybean plants. The activities of peroxidase, superoxide dismutase, and catalase increased, and the hydrogen peroxide (H2O2) as well as the superoxide radical (O2 -) content in soybean leaves decreased after T-aloe pretreatment in response to S. sclerotiorum pathogen challenge. T-aloe treatment diminished damage caused by pathogen stress on soybean leaf cell membrane, and increased chlorophyll as well as total phenol contents. The defense-related genes PR1, PR2, and PR3 were expressed in the leaves of T-aloe-treated plants. In summary, T-aloe displayed biocontrol potential against S. sclerotiorum. This is the first report of unraveling biocontrol potential of Trichoderma Spp. to soybean sclerotinia stem rot from the three-way interaction between the biocontrol agent, pathogen S. sclerotiorum and soybean plants.


      PubDate: 2016-01-12T14:51:00Z
       
  • Spatial and temporal distribution of genes involved in polyamine
           metabolism during tomato fruit development
    • Abstract: Publication date: Available online 5 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Georgios Tsaniklidis, Anastasios Kotsiras, Athanasios Tsafouros, Peter A. Roussos, Georgios Aivalakis, Panagiotis Katinakis, Costas Delis
      Polyamines are organic compounds involved in various biological roles in plants, including cell growth and organ development. In the present study, the expression profile, the accumulation of free polyamines and the transcript localisation of the genes involved in Put metabolism, such as Ornithine decarboxylase (ODC), Arginine decarboxylase (ADC) and copper containing Amine oxidase (CuAO), were examined during Solanum lycopersicum cv. Chiou fruit development and maturation. Moreover, the expression of genes coding for enzymes involved in higher polyamine metabolism, including Spermidine synthase (SPDS), Spermine synthase (SPMS), S-adenosylmethionine decarboxylase (SAMDC) and Polyamine oxidase (PAO), were studied. Most genes participating in PAs biosynthesis and metabolism exhibited an increased accumulation of transcripts at the early stages of fruit development. In contrast, CuAO and SPMS were mostly expressed later, during the development stages of the fruits where a massive increase in fruit volume occurs, while the SPDS1 gene exhibited a rather constant expression with a peak at the red ripe stage. Although Put, Spd and Spm were all exhibited decreasing levels in developing immature fruits, Put levels maxed late during fruit ripening. In contrast to Put both Spd and Spm levels continue to decrease gradually until full ripening. It is worth noticing that in situ RNA-RNA hybridisation is reported for the first time in tomato fruits. The localisation of ADC2, ODC1 and CuAO gene transcripts at tissues such as the locular parenchyma and the vascular bundles fruits, supports the theory that all genes involved in Put biosynthesis and catabolism are mostly expressed in fast growing tissues. The relatively high expression levels of CuAO at the ImG4 stage of fruit development (fruits with a diameter of 3 cm), mature green and breaker stages could possibly be attributed to the implication of polyamines in physiological processes taking place during fruit ripening.
      Teaser • Nucleotide sequence data are available in the NCBI database under accession number CuAO (AJ871578).

      PubDate: 2016-01-08T02:02:16Z
       
  • Natural allelic variations of TCS1 play a crucial role in caffeine
           biosynthesis of tea plant and its related species
    • Abstract: Publication date: Available online 4 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Ji-Qiang Jin, Ming-Zhe Yao, Chun-Lei Ma, Jian-Qiang Ma, Liang Chen
      Tea caffeine synthase 1 (TCS1) is an enzyme that catalyzes the methylation of N-3 and N-1 and considered to be the most critical enzyme in the caffeine biosynthetic pathway of tea plant. This study shows that TCS1 has six types of allelic variations, namely, TCS1a, TCS1b, TCS1c, TCS1d, TCS1e, and TCS1f, with a 252 bp insertion/deletion mutation in the 5’-untranslated region. Among tea plant and its related species, TCS1a is the predominant allele, and TCS1b–f are the rare alleles that mainly appear in few wild germplasms. The full-length cDNA sequences of three new alleles, namely, TCS1d, TCS1e, and TCS1f, were isolated from specific germplasms, and all of recombinant proteins have higher caffeine synthase (CS, EC 2.1.1.160) activity than theobromine synthase (TS, EC 2.1.1.159). Amino acid residue 269 is responsible for the difference in TCS activity and substrate recognition, which was demonstrated by using site-directed mutagenesis experiments. Furthermore, natural variations in TCS1 change the transcription levels. There are two molecular mechanisms controlling the caffeine biosynthesis in low-caffeine-accumulating tea germplasms, i.e., TCS1 allele with low transcription level or its encoded protein with only TS activity. Allelic variations of TCS1 play a crucial role in caffeine biosynthesis. Taken together, our work provides valuable foundation for a comprehensive understanding of the mechanism of caffeine biosynthesis in section Thea plants and useful guidance for effective breeding.


      PubDate: 2016-01-08T02:02:16Z
       
  • Histone Acetylation Influences the Transcriptional Activation of POX in
           Beta vulgaris L. and Beta maritima L. under salt stress
    • Abstract: Publication date: Available online 4 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Seher Yolcu, Filiz Ozdemir, Aybüke Güler, Melike Bor
      Acetylation of histone proteins is a type of chromatin modification which facilitates the activation of genes. Recent studies brought up the importance of this reversible and rapid process for the regulation of gene expression especially in plant defense against a variety of environmental stresses. Deciphering the exact mechanisms of chromatin modifications under abiotic stress conditions is important for improving crop plants’ performance and yield. In a previous study we compared the salt stress responses of Beta vulgaris (sugar beet) and Beta maritima (wild beet). In accordance with those results we suggested that chromatin remodeling can be an active process in the regulation of genes related to salt stress tolerance of these plants. Therefore we performed ChIP assay in control and salt stressed (250 and 500 mM NaCl) plants and compared the enrichment of acetylation in the associated chromatin sites. We found that the transcriptional activation of one peroxidase (POX) encoding gene was associated with the eleviated levels of acetylation in H3K9 and H3K27 sites. The acetylation patterns were remarkably different between two species in which the highest acetylation levels were found at H3K9 and H3K27 in wild beet and sugar beet respectively.


      PubDate: 2016-01-08T02:02:16Z
       
  • Spatial distribution and dynamics of sucrose metabolising enzymes in
           radiation induced mutants of sugarcane
    • Abstract: Publication date: Available online 5 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): S.J. Mirajkar, P. Suprasanna, E.R. Vaidya
      Sucrose metabolism in various source and sink organs of developing sugarcane (Saccharum officinarum L.) plant is accompanied with continuous synthesis and cleavage. In this regard, the involvements of four major enzymes viz. sucrose synthase (SS), sucrose phosphate synthase (SPS), soluble acid (SAI) and neutral invertases (NI) is considered crucial. In this study, we have analysed in vivo enzymatic activity of 12th month old field grown radiation-induced sugarcane mutants identified for sucrose accumulation. The mutants showed significant differences in the spatial enzymatic regulation in leaves, immature and mature internodes; SPS and SS activities were found highest in high sucrose accumulating mutants (AKTS-02 and AKTS-20) along with lower levels of SAI activity. Overall positive correlation of SPS, SS and negative correlation of SAI, NI activities with sucrose content of the respective tissue types was observed. The SPS activity was found strongly associated with sucrose content in leaves (r2= 0.558) and internodes (r2= 0.514), whereas, the SAI activity was found significant in leaves (r2= 0.379) and weakly associated in internodal tissues (r2= 0.248). However, the associations were found to be non-significant for SS and NI activities in both leaves and internodes. Despite this, the differences in the SPS and SAI activities (SPS-SAI) in leaves (r2= 0.828) and internodal tissues (r2= 0.619) had shown greater influence on net sucrose synthesis and accumulation. To summarize, our results suggest differential sugar metabolism in the induced mutants and that such contrasting mutant germplasm with a relatively uniform genetic makeup can be useful in molecular studies on sucrose accumulation.


      PubDate: 2016-01-08T02:02:16Z
       
  • Leaf malate and succinate accumulation are out of phase throughout the
           development of the CAM plant Ananas comosus
    • Abstract: Publication date: Available online 6 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): N. Rainha, V.P. Medeiros, C. Ferreira, A. Raposo, J.P. Leite, C. Cruz, C.A. Pacheco, D. Ponte, A.B. Silva
      In plants with crassulacean acid metabolism (CAM), organic acids, mainly malate are crucial intermediates for carbon fixation. In this research we studied the circadian oscillations of three organic anions (malate, citrate, and succinate) in Ananas comosus, assessing the effect of season and plant development stage. Seasonal and plant development dependencies were observed. The circadian oscillations of malate and citrate were typical of CAM pathways reported in the literature. Citrate content was quite stable (25-30 μmol.g-1 FW) along the day, with a seasonal effect. Succinate was shown to have both diurnal and seasonal oscillations and also a correlation with malate, since it accumulated during the afternoon when malate content was normally at a minimum, suggesting a possible mechanistic effect between both anions in CAM and/or respiratory metabolisms.


      PubDate: 2016-01-08T02:02:16Z
       
  • Modification of oil and glucosinolate content in canola seeds with altered
           expression of Brassica napus LEAFY COTYLEDON1
    • Abstract: Publication date: Available online 5 January 2016
      Source:Plant Physiology and Biochemistry
      Author(s): Nosheen Elahi, Robert W. Duncan, Claudio Stasolla
      Over the last few decades, research focusing on canola (Brassica napus L.) seed oil content and composition has expanded. Oil production and accumulation are influenced by genes participating in embryo and seed development. The Arabidopsis LEAFY COTYLEDON1 (LEC1) is a well characterized regulator of embryo development that also enhances the expression of genes involved in fatty acid (FA) synthesis. Brassica napus lines over-expressing or down-regulating BnLEC1 were successfully generated by Agrobacterium-mediated transformation. The constitutive expression of BnLEC1 in Brassica napus var. Polo, increased seed oil content by 7 - 16%, while the down-regulation of BnLEC1 in Brassica napus var. Topas reduced oil content by 9-12%. Experimental manipulation of BnLEC1 caused transcriptional changes in enzymes participating in sucrose metabolism, glycolysis, and FA biosynthesis, suggesting an enhanced carbon flux towards FA biosynthesis in tissues over-expressing BnLEC1. The increase in oil content induced by BnLEC1 was not accompanied by alterations in FA composition, oil nutritional value or glucosinolate (GLS) levels. Suppression of BnLEC1 reduced seed oil accumulation and elevated the level of GLS possibly through the transcriptional regulation of BnST5a (Sulphotransferase5a), the last GLS biosynthetic enzyme. Collectively, these findings demonstrate that experimental alterations of BnLEC1 expression can be used to influence oil production and quality in Brassica napus.


      PubDate: 2016-01-08T02:02:16Z
       
  • Pseudomonas putida attunes morphophysiological, biochemical and molecular
           responses in Cicer arietinum L. during drought stress and recovery
    • Abstract: Publication date: February 2016
      Source:Plant Physiology and Biochemistry, Volume 99
      Author(s): Shalini Tiwari, Charu Lata, Puneet Singh Chauhan, Chandra Shekhar Nautiyal
      Drought is one of the most important abiotic stresses that adversely affect plant growth and yield potential. However, some drought resistant rhizosphere competent bacteria are known to improve plant health and promote growth during abiotic stresses. Present study showed the role of Pseudomonas putida MTCC5279 (RA) in ameliorating drought stress on cv. BG-362 (desi) and cv. BG-1003 (kabuli) chickpea cultivars under in vitro and green house conditions. Polyethylene glycol-induced drought stress severely affected seed germination in both cultivars which was considerably improved on RA-inoculation. Drought stress significantly affected various growth parameters, water status, membrane integrity, osmolyte accumulation, ROS scavenging ability and stress-responsive gene expressions, which were positively modulated upon application of RA in both chickpea cultivars. Quantitative real-time (qRT)-PCR analysis showed differential expression of genes involved in transcription activation (DREB1A and NAC1), stress response (LEA and DHN), ROS scavenging (CAT, APX, GST), ethylene biosynthesis (ACO and ACS), salicylic acid (PR1) and jasmonate (MYC2) signalling in both chickpea cultivars exposed to drought stress and recovery in the presence or absence of RA. The observations imply that RA confers drought tolerance in chickpea by altering various physical, physiological and biochemical parameters, as well as by modulating differential expression of at least 11 stress-responsive genes. To the best of our knowledge, this is the first report on detailed analysis of plant growth promotion and stress alleviation in one month old desi and kabuli chickpea subjected to drought stress for 0, 1, 3 and 7 days and recovery in the presence of a PGPR.


      PubDate: 2016-01-04T01:31:35Z
       
  • Reduced arsenic accumulation in rice (Oryza sativa L.) shoot involves
           sulfur mediated improved thiol metabolism, antioxidant system and altered
           arsenic transporters
    • Abstract: Publication date: February 2016
      Source:Plant Physiology and Biochemistry, Volume 99
      Author(s): Garima Dixit, Amit Pal Singh, Amit Kumar, Seema Mishra, Sanjay Dwivedi, Smita Kumar, Prabodh Kumar Trivedi, Vivek Pandey, Rudra Deo Tripathi
      Arsenic (As) contamination in rice is at alarming level as majority of rice growing regions are As contaminated such as South East Asia. Restricting the As in aerial parts of rice plant may be an effective strategy to reduce As contamination in food chain. Sulfur (S), an essential element for plant growth and development, plays a crucial role in diminishing heavy metal toxicity. Current study is designed to investigate the role of S to mitigate As toxicity in rice under different S regimes. High S (5 mM) treatment resulted in enhanced root As accumulation as well as prevented its entry in to shoot. Results of thiol metabolism indicate that As was complexed in plant roots through enhanced synthesis of phytochelatins. High S treatment also reduced the expression of OsLsi1 and OsLsi2, the potent transporters of As in rice. High S treatment enhanced the activities of antioxidant enzymes and mitigated the As induced oxidative stress. Thus from present study it is evident that proper supply of S nutrition may be helpful in prevention of As accumulation in aerial parts of plant as well as As induced toxicity.


      PubDate: 2015-12-30T10:00:39Z
       
  • Dehydrins from wheat x Thinopyrum ponticum amphiploid increase salinity
           and drought tolerance under their own inducible promoters without growth
           retardation
    • Abstract: Publication date: Available online 29 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Yu-xiang Qin, Fangyuan Qin
      Dehydrins confer abiotic stress tolerance in seedlings, but few dehydrins have been studied by transgenic analysis under their own promoters in relation to abiotic stress tolerance. Also the inducible promoters for transgenic engineering are limited. In this study, we isolated from wheat three salt-induced YSK2 dehydrin genes and their promoters. The cDNA sequences were 711, 785, and 932 bp in length, encoding proteins containing 133, 166 and 231 amino acids, respectively, and were named TaDHN1, TaDHN2, and TaDHN3. TaDHN2 doesn’t contain introns, while the other two genes each contain one. Semi-quantitative reverse transcription PCR analysis revealed all three dehydrin genes are substantially induced by ABA and NaCl, but only TaDHN2 is induced in seedlings by PEG and by cold (4 °C). Regulatory sequences upstream of the first translation codon (775, 1615 and 889 bp) of the three dehydrin genes were also cloned. Cis-element prediction indicated the presence of ABRE and other abiotic-stress-related elements. Histochemical analysis using GUS expression demonstrated that all three promoters were induced by ABA, cold or NaCl. Ectopic over-expression of TaDHN1 or TaDHN3 in Arabidopsis under their own inducible promoters enhanced NaCl- and drought-stress tolerance without growth retardation.


      PubDate: 2015-12-30T10:00:39Z
       
  • Structural basis of the lack of endo-glucanase inhibitory activity of
           Lupinus albus γ-conglutin
    • Abstract: Publication date: February 2016
      Source:Plant Physiology and Biochemistry, Volume 99
      Author(s): Alessio Scarafoni, Alessandro Consonni, Stefano Pessina, Silvia Balzaretti, Jessica Capraro, Elisabetta Galanti, Marcello Duranti
      Lupin γ-conglutin and soybean BG7S are two legume seed proteins strongly similar to plant endo-β-glucanases inhibitors acting against fungal GH11 and GH12 glycoside hydrolase. However these proteins lack inhibitory activity. Here we describe the conversion of lupin γ-conglutin to an active inhibitor of endo-β-glucanases belonging to GH11 family. A set of γ-conglutin mutants was designed and expressed in Pichia pastoris, along with the wild-type protein. Unexpectedly, this latter was able to inhibit a GH11 enzyme, but not GH12, whereas the mutants were able to modulate the inhibition capacity. In lupin, γ-conglutin is naturally cleaved in two subunits, whereas in P. pastoris it is not. The lack of proteolytic cleavage is one of the reasons at the basis of the inhibitory activity of recombinant γ-conglutin. The results provide new insights about structural features at the basis of the lack of inhibitory activity of wild-type γ-conglutin and its legume homologues.


      PubDate: 2015-12-30T10:00:39Z
       
  • Heterologous complementation studies reveal the solute transport profiles
           of a two-member Nucleobase Cation Symporter 1 (NCS1) family in
           Physcomitrella patens
    • Abstract: Publication date: Available online 29 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Janet A. Minton, Micah Rapp, Amanda J. Stoffer, Neil P. Schultes, George S. Mourad
      As part of an evolution-function analysis, two Nucleobase Cation Symporter 1 (NCS1) from the moss Physcomitrella patens (PpNCS1A and PpNCS1B) are examined – the first such analysis of nucleobase transporters from early land plants. The solute specificity profiles for the moss NCS1 were determined through heterologous expression, growth and radiolabeled uptake experiments in NCS1-deficient Saccharomyces cerevisiae. Both PpNCS1A and 1B, share the same profiles as high affinity transporters of adenine and transport uracil, guanine, 8-azaguanine, 8-azaadenine, cytosine, 5-fluorocytosine, hypoxanthine, and xanthine. Despite sharing the same solute specificity profile, PpNCS1A and PpNCS1B move nucleobase compounds with different efficiencies. The broad nucleobase transport profile of PpNCS1A and 1B differs from the recently-characterized Viridiplantae NCS1 in breadth, revealing a flexibility in solute interactions with NCS1 across plant evolution.


      PubDate: 2015-12-30T10:00:39Z
       
  • Changes in biochemical compounds in Flesh and Peel from Prunus persica
           Fruits grown in Tunisia during two Maturation Stages
    • Abstract: Publication date: Available online 28 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Samia Dabbou, Carola Lussiana, Samira Maatallah, Laura Gasco, Hichem Hajlaloui, Guido Flamini
      Plants can synthesize tens to hundreds of thousands of primary and secondary metabolites with diverse biological properties and functions. Fatty acids (FA), phenolic compounds (PC) and volatile compounds (VC) of flesh and peel from three Prunus persica cultivars were evaluated at the Regional Centre of Agricultural Research - Experimental Farm (Sidi Bouzid, Tunisia) during two maturation stages. Palmitic, oleic and linoleic acids are the most abundant FA in Prunus persica cultivars. A genetic effect on FA composition was observed throughout the two sampling periods. Peel was rich in oleic acid with the highest content (31.3% on total FA) in 'O'Henry' cultivar at the commercial ripening date; flesh was rich in linoleic acid with the highest content (44.7% on total FA) in 'Sweet Cap' cultivar at the full ripening date. The monounsaturated/polyunsaturated fatty acids ratios were higher in the commercial ripe than in the full ripe fruits. The analysis of the composition of the VC led to the characterization of 98 different compounds, showing a very high variability among the cultivars. The full ripe fruit (peel and flesh) exhibited the highest total number of terpenoids. Commercial ripe peels were richest in the percentage of hydrocarbons. Comparing cultivars, 'Sweet Cap' cultivar showed the lowest contents of alcohols in peel and flesh of full ripe fruit but highest in peel of commercial ripe fruit, and lowest content of aldehydes in peel and flesh of commercial ripe fruit but highest in peel of ripe ones and the highest ones of lactones. Among PC, the highest contents were observed for o-diphenols and the values showed varietal influence. Total phenols contents decreased during ripening process (p<0.05) in both peel and flesh tissues, except found for 'Sweet Cap' cultivar. In conclusion, to achieve better FA composition and greater VC and PC production of the peach fruit, Prunus persica cultivars should be harvested at the commercial ripening date.
      Graphical abstract image

      PubDate: 2015-12-30T10:00:39Z
       
  • Salvaging effect of triacontanol on plant growth, thermotolerance,
           macro-nutrient content, amino acid concentration and modulation of defense
           hormonal levels under heat stress
    • Abstract: Publication date: Available online 24 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Muhammad Waqas, Raheem Shahzad, Abdul Latif Khan, Sajjad Asaf, Yoon-Ha Kim, Sang-Mo Kang, Saqib Bilal, Muhammad Hamayun, In-Jung Lee
      In this study, it was hypothesized that application of triacontanol, a ubiquitous saturated primary alcohol, at different times—before (TBHS), mid (TMHS), and after (TAHS) heat stress—will extend heat stress (HS) protection in mungbean. The effect of triacontanol on the levels of defense hormones abscisic acid (ABA) and jasmonic acid (JA) was investigated along with the plant growth promotion, nutrient and amino acid content with and without heat stress. Heat stress caused a prominent reduction in plant growth attributes, nutrient and amino acid content, which were attributed to the decreased level of ABA and JA. However, application of triacontanol, particularly in the TBHS and TMHS treatments, reversed the deleterious effects of HS by showing increased ABA and JA levels that favored the significant increase in plant growth attributes, enhanced nutrient content, and high amount of amino acid. TAHS, a short-term application of triacontanol, also significantly increased ABA and JA levels and thus revealed important information of its association with hormonal modulation. The growth-promoting effect of triacontanol was also confirmed under normal growth conditions. To the best of our knowledge, this study is the first to demonstrate the beneficial effects of triacontanol, with or without heat stress, on mungbean and its interaction with or regulation of the levels of defense hormones.


      PubDate: 2015-12-25T23:06:18Z
       
  • Molecular characterization and expression analysis of the mulberry Na+/H+
           exchanger gene family
    • Abstract: Publication date: Available online 20 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Boning Cao, Dingpei Long, Meng Zhang, Changying Liu, Zhonghuai Xiang, Aichun Zhao
      Na+/H+ exchangers (NHXs) have important roles in cellular pH, and Na+ and K+ homeostasis in plants. Mulberry is not only an important traditional economic woody plant known for its leaves, which are the exclusive food source of the silkworm Bombyx mori, but it can also adapt to many different adverse conditions, including saline environments. However, little is known about the NHXs in this important perennial tree. In this study, we identified and cloned seven putative NHX gene family members from Morus atropurpurea based on a genome-wide analysis of the Morus genome database. A phylogenetic analysis and genomic organization of mulberry NHXs suggested that the mulberry NHX family forms three distinct subgroups. Transcriptome data and real-time PCR of different mulberry varieties under normal culture conditions revealed that the mulberry NHX family has a different tissue-specific pattern in the two mulberry species. The MaNHX genes’ expression analyses under different stresses (salt and drought) and signal molecules (abscisic acid, salicylic acid, hydrogen peroxide and methyl jasmonate) revealed that MaNHXs not only could be induced by salt, drought and abscisic acid as describe in the literature, but were also induced by other signal molecules, which indicated that MaNHX members exhibited diverse and complicated expression patterns in different mulberry tissues under various abiotic stresses, phytohormones and plant signaling molecules. Our results provide some insights into new and emerging cellular and physiological functions of this group of H+-coupled cation exchangers, beyond their function in salt tolerance, and also provide the basis for further characterizations of MaNHXs’ physiological functions.


      PubDate: 2015-12-21T22:59:18Z
       
  • Sexually different morphological, physiological and molecular responses of
           Fraxinus mandshurica flowers to floral development and chilling stress
    • Abstract: Publication date: Available online 20 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Zhuzhu, Fenghui Qi, Chaofu Yan, Yaguang Zhan
      Fraxinus mandshurica is considered a dioecious hardwood, and the temporal separation of the maturation of the male and female flowers is one reason that F. mandshurica has become an endangered species in China. Rainfall and low temperature influence pollen formation and dispersal and the blooming of female flowers. Therefore, low fertilization efficiency strongly influences the population of F. mandshurica. Nevertheless, few studies have investigated the sex-specific morphological, physiological and molecular differentiation of F. mandshurica during flowering and its responses to low temperature. In this study, we investigated the sexual differences in the morphological, physiological, and biochemical parameters of F. mandshurica during flowering and determined the physiological and biochemical parameters and expression levels of related genes in response to low-temperature stress induced by exposure to 4°C (chilling stress) during pollen dispersal and fertilization. Our study supports the hypothesis that male flowers suffer more severe injuries while female flowers are more adaptable to environmental stress during flower development in F. mandshurica. The results showed higher physiological and biochemical levels of malondialdehyde, proline, and soluble sugar, as well as the expression of genes involved in calcium signaling, cold shock and DNA methylation in male flowers compared with female flowers, which suggested that male flowers suffer from more serious peroxidation than female flowers. In contrast, higher antioxidant capacity and FmaCAT expression were detected in female flowers, providing preliminary evidence that male flowers rapidly fade after pollination and further demonstrating that female flowers need a much stronger antioxidant enzyme system to maintain embryonic growth. Most peaks related to physiological and molecular responses were observed at 2-4 h and 8-10 h of exposure to chilling stress in the female and male flowers, respectively. This trend implies that female flowers have higher adaptability to low temperature during fertilization.


      PubDate: 2015-12-21T22:59:18Z
       
  • Comparative proteomic analysis of β-aminobutyric acid-mediated
           alleviation of salt stress in barley
    • Abstract: Publication date: Available online 18 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Agnieszka Mostek, Andreas Börner, Stanisław Weidner
      The non-protein amino acid β-aminobutyric acid (BABA) is known to induce plant resistance to a broad spectrum of biotic and abiotic stresses. This is the first study describing the effect of BABA seed priming on physiological and proteomic changes under salt stress conditions in barley (Hordeum vulgare). The aim of our study was to investigate the changes of fresh weight, dry weight and relative water content (RWC) as well as root proteome changes of two barley lines contrasting in salt tolerance (DH14, DH187) in response to salt-stress after seed priming in water or in 800 μM BABA. Seed priming with BABA significantly increased (p ≤ 0.05) RWC in both barley lines, which indicates considerably lower water loss in BABA-primed plants than in the non-primed control plants. Dry and fresh matter increased significantly in line DH187, whereas no changes were detected in line DH14. BABA-primed plants of both lines showed different proteomic patterns than the non-primed control plants. The root proteins exhibiting significant abundance changes (1.75-fold change, p ≤ 0.05) were separated by two-dimensional polyacrylamide gel electrophoresis (2D- PAGE). Thirty-one spots, representing 24 proteins, were successfully identified by MALDI-TOF/TOF mass spectrometry. The most prominent differences include the up-regulation of antioxidant enzymes (catalase, peroxidase and superoxide dismutase), PR proteins (chitinase, endo-1,3-β-glucosidase), and chaperones (cyclophilin, HSC70). Our results indicate that BABA induces defence and detoxification processes which may enable faster and more effective responses to salt stress, increasing the chances of survival under adverse environmental conditions.


      PubDate: 2015-12-21T22:59:18Z
       
  • New strategies for the use of Linum usitatissimum cell factories for the
           production of bioactive compounds
    • Abstract: Publication date: Available online 18 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Lorena Almagro, Pascual García-Pérez, Sarai Belchí-Navarro, Pedro Joaquín Sánchez-Pujante, M.A. Pedreño
      In this work, suspension-cultured cells of Linum usitatissimum L. were used to evaluate the effect of two types of cyclodextrins, β-glucan and (Z)-3-hexenol separately or in combination on phytosterol and tocopherol production. Suspension-cultured cells of L. usitatissimum were able to produce high levels of phytosterols in the presence of 50 mM methylated-β-cyclodextrins (1325,96 ± 107,06 μg.g dry weight-1) separately or in combination with β-glucan (1278,57 ± 190,10 μg.g dry weight-1) or (Z)-3-hexenol (1507,88 ± 173,02 μg.g dry weight-1), being cyclodextrins able to increase both the secretion and accumulation of phytosterols in the spent medium, whereas β-glucan and (Z)-3-hexenol themselves only increased its intracellular accumulation. Moreover, the phytosterol values found in the presence of hydroxypropylated-β-cyclodextrins were lower than those found in the presence of methylated-β-cyclodextrins in all cases studied. However, the results showed that the presence of methylated-β-cyclodextrins did not increase the tocopherols production and only an increase in tocopherol levels was observed when cells were elicited with 50 mM hydroxypropylated-β-cyclodextrins in combination with β-glucan (174 μg.g dry weight-1) or (Z)-3-hexenol (257 μg.g dry weight-1). Since the levels of tocopherol produced in the combined treatment were higher than the sum of the individual treatments, a synergistic effect between both elicitors was assumed. To sum up, flax cell cultures elicited with cyclodextrins alone or in combination with β-glucan or (Z)-3-hexenol were able produce phytosterols and tocopherols, and therefore, these elicited suspension-cultured cells of L. usitatissimum can provide an alternative system, which is at the same time more sustainable, economical and ecological for their production.


      PubDate: 2015-12-21T22:59:18Z
       
  • Characterization of glutamate decarboxylase from Synechocystis sp. PCC6803
           and its role in nitrogen metabolism
    • Abstract: Publication date: Available online 18 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Simab Kanwal, Aran Incharoendsakdi
      Glutamate decarboxylase (GAD) (EC 4.1.1.15), an enzyme responsible for the synthesis of γ -aminobutyric acid (GABA), from Synechocystis sp. PCC6803 was cloned and overexpressed in Escherichia coli BL21(DE3). The purified enzyme was expressed as a monomeric protein with a molecular mass of 53 and 55 kDa as determined by SDS-PAGE and gel filtration chromatography, respectively. The enzyme activity was pyridoxal 5/-phosphate dependent with an optimal activity at pH 6.0 and 30 °C. The catalytic properties of this enzyme were, K m = 19.6 mM; k cat = 100.7 s-1; and k cat /K m = 5.1 mM-1 s-1. The transcription levels of genes involved in nitrogen metabolism were up-regulated in the Δgad strain. The mutant showed approximately 4 - and 8 -fold increases in the transcript levels of kgd and gabdh encoding a novel α-ketoglutarate decarboxylase and γ -aminobutanal dehydrogenase, respectively. Overall results suggested that in Synechocystis lacking a functional GAD, the γ -aminobutanal dehydrogenase might serve as an alternative catalytic pathway for GABA synthesis.


      PubDate: 2015-12-21T22:59:18Z
       
  • Physiological and biochemical characterisation of watered and
           drought-stressed barley mutants in the HvDWARF gene encoding C6-oxidase
           involved in brassinosteroid biosynthesis
    • Abstract: Publication date: Available online 20 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Anna Janeczko, Damian Gruszka, Ewa Pociecha, Michał Dziurka, Maria Filek, Barbara Jurczyk, Hazem M. Kalaji, Maciej Kocurek, Piotr Waligórski
      Brassinosteroids (BR) are plant steroid hormones that were discovered more than thirty years ago, but their physiological function has yet to be fully explained. The aim of the study was to answer the question of whether/how disturbances in the production of BR in barley affects the plant’s metabolism and development under conditions of optimal watering and drought. Mutants with an impaired production of BR are one of the best tools in research aimed at understanding the mechanisms of action of these hormones. The study used barley cultivars with a normal BR synthesis (wild type) and semi-dwarf allelic mutants with an impaired activity of C6-oxidase (mutation in HvDWARF), which resulted in a decreased BR synthesis. Half of the plants were subjected to drought stress in the seedling stage and the other half were watered optimally. Plants with impaired BR production were characterised by a lower height and developmental retardation. Under both optimal watering and drought, BR synthesis disorders caused the reduced production of ABA and cytokinins, but not auxins. The BR mutants also produced less osmoprotectant (proline). The optimally watered and drought-stressed mutants accumulated less sucrose, which was accompanied by changes in the production of other soluble sugars. The increased content of fructooligosaccharide (kestose) in optimally watered mutants would suggest that BR is a negative regulator of kestose production. The decreased level of nystose in the drought-stressed mutants also suggests BR involvement in the regulation of the production of this fructooligosaccharide. The accumulation of the transcripts of genes associated with stress response (hsp90) was lower in the watered and drought-stressed BR-deficient mutants. In turn, the lower efficiency of photosystem II and the net photosynthetic rate in mutants was revealed only under drought conditions. The presented research allows for the physiological and biochemical traits of two BR-barley mutants to be characterised, which helps BR function to be understood. The knowledge can also be a good starting point for some breeding companies that are interested in introducing new semi-dwarf barley cultivars.
      Graphical abstract image

      PubDate: 2015-12-21T22:59:18Z
       
  • Endogenous hormone levels affect the regeneration ability of callus
           derived from different organs in barley
    • Abstract: Publication date: Available online 17 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Hiroshi Hisano, Takakazu Matsuura, Izumi C. Mori, Miki Yamane, Kazuhiro Sato
      Hordeum vulgare (barley) is an important agricultural crop worldwide. A simple and efficient transformation system is needed to analyze the functions of barley genes and generate lines with improved agronomic traits. Currently, Golden Promise and Igri are the most amenable barley cultivars to stable transformation. Here we evaluated the regeneration ratios and endogenous hormone levels of calli derived from various malting barley cultivars, including Golden Promise, Haruna Nijo, and Morex. We harvested samples not only from immature embryos, but also from different explants of juvenile plants, cotyledons, coleoptiles, and roots. The callus properties differed among genotypes and explant types. Calli derived from the immature embryos of Golden Promise, which showed the highest ratio of regeneration of green shoots, had the highest contents of indoleacetic acid, trans-zeatin, and cis-zeatin. By contrast, calli derived from the cotyledons of Morex and the immature embryos of Haruna Nijo had elevated levels of salicylic acid and abscisic acid, respectively. We thus propose that the former phytohormones are positively associated with the regeneration ability of callus but the later phytohormones are negatively associated.


      PubDate: 2015-12-17T22:23:39Z
       
  • Changes in nutrient distribution are part of the mechanism that promotes
           seed development under severe nutrient restriction
    • Abstract: Publication date: Available online 14 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Patricia Coello, Eleazar Martínez-Barajas
      When bean fruits are detached from a plant at 20 days after anthesis (DAA), the material accumulating in the pod is relocalized to the seeds. This mobilization is more active during the first five days after the fruits are removed, which allows some seeds to continue their development. In freshly removed fruits, 14C-sucrose was evenly distributed among seeds; however, in fruits that were removed three days before, the labeled sugar was concentrated in 1-2 seeds. In addition, in removed pods, embryos dissected from seeds that no longer continue development can assimilate and efficiently use sucrose for protein and starch synthesis. Our results support the hypothesis that most embryos in removed fruits are forced to stop developing by removal of the nutrient supply. We also observed that SnRK1 activity increased in embryos that were subjected to nutrient deprivation, supporting the role of SnRK1 in the metabolic adaptation to stress conditions.


      PubDate: 2015-12-17T22:23:39Z
       
  • Microarray-based gene expression analysis of strong seed dormancy in rice
           cv. N22 and less dormant mutant derivatives
    • Abstract: Publication date: Available online 9 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Tao Wu, Chunyan Yang, Baoxu Ding, Zhiming Feng, Qian Wang, Jun He, Jianhua Tong, Langtao Xiao, Ling Jiang, Jianmin Wan
      Seed dormancy in rice is an important trait related to the pre-harvest sprouting resistance. In order to understand the molecular mechanisms of seed dormancy, gene expression was investigated by transcriptome analysis using seeds of the strongly dormant cultivar N22 and its less dormant mutants Q4359 and Q4646 at 24 days after heading (DAH). Microarray data revealed more differentially expressed genes in Q4359 than in Q4646 compared to N22. Most genes differing between Q4646 and N22 also differed between Q4359 and N22. GO analysis of genes differentially expressed in both Q4359 and Q4646 revealed that some genes such as those for starch biosynthesis were repressed, whereas metabolic genes such as those for carbohydrate metabolism were enhanced in Q4359 and Q4646 seeds relative to N22. Expression of some genes involved in cell redox homeostasis and chromatin remodeling differed significantly only between Q4359 and N22. The results suggested a close correlation between cell redox homeostasis, chromatin remodeling and seed dormancy. In addition, some genes involved in ABA signaling were down-regulated, and several genes involved in GA biosynthesis and signaling were up-regulated. These observations suggest that reduced seed dormancy in Q4359 was regulated by ABA-GA antagonism. A few differentially expressed genes were located in the regions containing qSdn-1 and qSdn-5 suggesting that they could be candidate genes underlying seed dormancy. Our work provides useful leads to further determine the underling mechanisms of seed dormancy and for cloning seed dormancy genes from N22.


      PubDate: 2015-12-14T06:21:38Z
       
  • The interaction between iron nutrition, plant species and soil type shapes
           the rhizosphere microbiome
    • Abstract: Publication date: Available online 9 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Youry Pii, Luigimaria Borruso, Lorenzo Brusetti, Carmine Crecchio, Stefano Cesco, Tanja Mimmo
      Plant-associated microorganisms can stimulate plants growth and influence both crops yield and quality by nutrient mobilization and transport. Therefore, rhizosphere microbiome appears to be one of the key determinants of plant health and productivity. The roots of plants have the ability to influence its surrounding microbiology, the rhizosphere microbiome, through the creation of specific chemical niches in the soil mediated by the release of phytochemicals (i.e. root exudates) that depends on several factors, such as plants genotype, soil properties, plant nutritional status, climatic conditions. In the present research, two different crop species, namely barley and tomato, characterized by different strategies for Fe acquisition, have been grown in the RHIZOtest system using either complete or Fe-free nutrient solution to induce Fe starvation. Afterward, plants were cultivated for 6 days on two different calcareous soils. Total DNA was extracted from rhizosphere and bulk soil and 454 pyrosequencing technology was applied to V1–V3 16S rRNA gene region. Approximately 5000 sequences were obtained for each sample. The analysis of the bacterial population confirmed that the two bulk soils showed a different microbial community. The presence of the two plant species, as well as the nutritional status (Fe-deficiency and Fe-sufficiency), could promote a differentiation of the rhizosphere microbiome, as highlighted by non-metric multidimensional scaling (NMDS) analysis. Alphaproteobacteria, Actinobacteria, Chloracidobacteria, Thermoleophilia, Betaproteobacteria, Saprospirae, Gemmatimonadetes, Gammaproteobacteria, Acidobacteria were the most represented classes in all the samples analyzed even though their relative abundance changed as a function of the soil, plant species and nutritional status. To our knowledge, this research demonstrate for the first time that different plants species with a diverse nutritional status can promote the development of a peculiar rhizosphere microbiome, depending on the growth substrate.


      PubDate: 2015-12-14T06:21:38Z
       
  • Modulation of Pb-induced stress in Prosopis shoots through an
           interconnected network of signaling molecules, phenolic compounds and
           amino acids
    • Abstract: Publication date: Available online 11 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Somaieh Zafari, Mohsen Sharifi, Najmeh Ahmadian Chashmi, Luis A.J. Mur
      Lead (Pb) is a hazardous heavy metal present in the environment which elicits oxidative stress in plants. To characterize the physiological and biochemical basis of Pb tolerance, Prosopis farcta seedlings were exposed to Hoagland’s solutions at six different Pb concentrations (0, 80, 160, 320, 400 and 480 μM) for different periods of time. As expected, application of Pb significantly increased hydrogen peroxide (H2O2) content. In response, P. farcta deployed the antioxidative defence mechanisms with significantly higher activities of superoxide dismutase (SOD), enzymes related to H2O2 removal, and also the increases in proline as a solute marker of stress. Increases were observed in nitric oxide (NO) production which could also act in triggering defense functions to detoxify Pb. Enhanced phenylalanine ammonia-lyase (PAL) activity at early days of exposure to Pb was correlated with increases in phenolic compounds. Significant increases in phenolic acids and flavonoids; daidzein, vitexin, ferulic acid and salicylic acid were observed with Pb treatment. Furthermore, the stress effects were followed by changes in free amino acid content and composition. Aspartic acid and glycine content was increased but glutamic acid significantly decreased. It is likely that stress signal transduction by NO and H2O2 mediated defence responses to Pb by coordination of antioxidative system and metabolic pathways of phenylpropanoid and amino acids.
      Graphical abstract image

      PubDate: 2015-12-14T06:21:38Z
       
  • Identification and Expression Analysis of Heat Shock Transcription Factors
           in the Wild Chinese Grapevine (Vitis pseudoreticulata)
    • Abstract: Publication date: Available online 2 December 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Yang Hu, Yong-Tao Han, Kai Zhang, Feng-Li Zhao, Ya-Juan Li, Yi Zheng, Yue-Jin Wang, Ying-Qiang Wen
      Heat shock transcription factors (Hsfs) are known to play pivotal roles in the adaptation of plants to heat stress and other stress stimuli. While grapevine (Vitis vinifera L.) is one of the most important fruit crops worldwide, little is known about the Hsf family in Vitis spp. Here, we identified nineteen putative Hsf genes (VviHsfs) in Vitis spp based on the 12× grape genome (V. vinifera L.). Phylogenetic analysis revealed three classes of grape Hsf genes (classes A, B, and C). Additional comparisons between grape and Arabidopsis thaliana demonstrated that several VviHsfs genes occurred in corresponding syntenic blocks of Arabidopsis. Moreover, we examined the expression profiles of the homologs of the VviHsfs genes (VpHsfs) in the wild Chinese Vitis pseudoreticulata accession Baihe-35-1, which is tolerant to various environmental stresses. Among the nineteen VpHsfs, ten VpHsfs displayed lower transcript levels under non-stress conditions and marked up-regulation during heat stress treatment; several VpHsfs also displayed altered expression levels in response to cold, salt, and hormone treatments, suggesting their versatile roles in response to stress stimuli. In addition, eight VpHsf-GFP fusion proteins showed differential subcellular localization in V. pseudoreticulata mesophyll protoplasts. Taken together, our data may provide an important reference for further studies of Hsf genes in Vitis spp.


      PubDate: 2015-12-04T10:21:16Z
       
 
 
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