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Journal Cover Plant Physiology and Biochemistry
  [SJR: 1.167]   [H-I: 84]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0981-9428
   Published by Elsevier Homepage  [3039 journals]
  • Genome-wide transcriptome profiling of black poplar (Populus nigra L.)
           under boron toxicity revealed candidate genes responsible in boron uptake,
           transport and detoxification
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Kubilay Yıldırım, Senem Uylaş
      Boron (B) is an essential nutrient for normal growth of plants. Despite its low abundance in soils, it could be highly toxic to plants in especially arid and semi-arid environments. Poplars are known to be tolerant species to B toxicity and accumulation. However, physiological and gene regulation responses of these trees to B toxicity have not been investigated yet. Here, B accumulation and tolerance level of black poplar clones were firstly tested in the current study. Rooted cutting of these clones were treated with elevated B toxicity to select the most B accumulator and tolerant genotype. Then we carried out a microarray based transcriptome experiment on the leaves and roots of this genotype to find out transcriptional networks, genes and molecular mechanisms behind B toxicity tolerance. The results of the study indicated that black poplar is quite suitable for phytoremediation of B pollution. It could resist 15 ppm soil B content and >1500 ppm B accumulation in leaves, which are highly toxic concentrations for almost all agricultural plants. Transcriptomics results of study revealed totally 1625 and 1419 altered probe sets under 15 ppm B toxicity in leaf and root tissues, respectively. The highest induction were recorded for the probes sets annotated to tyrosine aminotransferase, ATP binding cassette transporters, glutathione S transferases and metallochaperone proteins. Strong up regulation of these genes attributed to internal excretion of B into the cell vacuole and existence of B detoxification processes in black poplar. Many other candidate genes functional in signalling, gene regulation, antioxidation, B uptake and transport processes were also identified in this hyper B accumulator plant for the first time with the current study.

      PubDate: 2016-09-25T09:15:02Z
       
  • Subcellular location of Arabidopsis thaliana subfamily a1
           β-galactosidases and developmental regulation of transcript
           levels of their coding genes
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): María Moneo-Sánchez, Lucía Izquierdo, Ignacio Martín, Emilia Labrador, Berta Dopico
      The aim of this work is to gain insight into the six members of the a1 subfamily of the β-galactosidases (BGAL) from Arabidopsis thaliana. First, the subcellular location of all these six BGAL proteins from a1 subfamily has been established in the cell wall by the construction of transgenic plants producing the enhanced green fluorescent protein (eGFP) fused to the BGAL proteins. BGAL12 is also located in the endoplasmic reticulum. Our study of the AtBGAL transcript accumulation along plant development indicated that all AtBGAL transcript appeared in initial stages of development, both dark- and light-grown seedlings, being AtBGAL1, AtBGAL2 and AtBGAL3 transcripts the predominant ones in the latter condition, mainly in the aerial part and with levels decreasing with age. The high accumulation of transcript of AtBGAL4 in basal internodes and in leaves at the end of development, and their strong increase after treatment both with BL and H3BO3 point to an involvement of BGAL4 in cell wall changes leading to the cease of elongation and increased rigidity. The changes of AtBGAL transcript accumulation in relation to different stages and conditions of plant development, suggest that each of the different gene products have a plant-specific function and provides support for the proposed function of the subfamily a1 BGAL in plant cell wall remodelling for cell expansion or for cell response to stress conditions.

      PubDate: 2016-09-25T09:15:02Z
       
  • Drought increases cowpea (Vigna unguiculata [L.] Walp.) susceptibility to
           cowpea severe mosaic virus (CPSMV) at early stage of infection
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Rodolpho G.G. Silva, Ilka M. Vasconcelos, Thiago F. Martins, Anna L.N. Varela, Pedro F.N. Souza, Ana K.M. Lobo, Fredy D.A. Silva, Joaquim A.G. Silveira, Jose T.A. Oliveira
      The physiological and biochemical responses of a drought tolerant, virus-susceptible cowpea genotype exposed to drought stress (D), infected by Cowpea severe mosaic virus (CPSMV) (V), and to these two combined stresses (DV), at 2 and 6 days post viral inoculation (DPI), were evaluated. Gas exchange parameters (net photosynthesis, transpiration rate, stomatal conductance, and internal CO2 partial pressure) were reduced in D and DV at 2 and 6 DPI compared to control plants (C). Photosynthesis was reduced by stomatal and biochemical limitations. Water use efficiency increased at 2 DPI in D, DV, and V, but at 6 DPI only in D and DV compared to C. Photochemical parameters (effective quantum efficiency of photosystem II and electron transport rate) decreased in D and DV compared to C, especially at 6 DPI. The potential quantum efficiency of photosystem II did not change, indicating reversible photoinhibition of photosystem II. In DV, catalase decreased at 2 and 6 DPI, ascorbate peroxidase increased at 2 DPI, but decreased at 6 DPI. Hydrogen peroxide increased at 2 and 6 DPI. Peroxidase increased at 6 DPI and chitinase at 2 and 6 DPI. β-1,3-glucanase decreased in DV at 6 DPI compared to V. Drought increased cowpea susceptibility to CPSMV at 2 DPI, as verified by RT-PCR. However, at 6 DPI, the cowpea plants overcome this effect. Likewise, CPSMV increased the negative effects of drought at 2 DPI, but not at 6 DPI. It was concluded that the responses to combined stresses are not additive and cannot be extrapolated from the study of individual stresses.

      PubDate: 2016-09-25T09:15:02Z
       
  • Growth and photosynthetic limitation analysis of the Cd-accumulator
           Salicornia ramosissima under excessive cadmium concentrations and optimum
           salinity conditions
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Jesús Alberto Pérez-Romero, Susana Redondo-Gómez, Enrique Mateos-Naranjo
      Cadmium (Cd) is a non-essential element for plants, and its excess impairs plant performance. Physiological impacts of Cd excess are well known in non-tolerant plants, however this information is scarce for Cd-tolerant plants. A glasshouse experiment was designed to investigate the effect of five different Cd levels (0, 0.05, 0.20, 0.65 and 1.35 mM Cd) on the growth, photosynthetic apparatus (PSII chemistry), gas exchange characteristics, photosynthetic pigments profiles, water relations and nutritional balance of the Cd-accumulator Salicornia ramosissima. Ours results confirmed the accumulation capacity of S. ramosissima, as indicated the bioaccumulation factor (BC) greater than 1.0 for all Cd levels. Furthermore, after 21 days of treatment S. ramosissima growth was not highly affected by Cd. Total photosynthetic limitation increased from 38% at 0.05 mM Cd to 70% at 1.35 mM Cd. CO2 diffusion restriction imposed the main contribution to total photosynthetic limitation. Mesophyll conductance reduction was of major importance (with between 69 and 86%), followed by stomatal conductance (with between 9 and 20%). Maximum carboxylation rate (V c,max), remained stable until 0.2 mM Cd, and chlorophyll fluorescence parameters (Fv/Fm, qP) and pigments concentrations were not significantly decreased by increased Cd supply. Finally, S. ramosissima water relations (intrinsic water use efficiency and relative water content) and nutritional level did not highly vary between Cd treatments. Thus, our finding suggested that Cd tolerance S. ramosissima is in certain degree supported by the tolerance of its carbon assimilation enzyme (RuBisCO) and with the high functionality and integrity of the PSII reaction center under Cd excess.

      PubDate: 2016-09-25T09:15:02Z
       
  • GhCaM7-like, a calcium sensor gene, influences cotton fiber elongation and
           biomass production
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Yuan Cheng, Lili Lu, Zhaoen Yang, Zhixia Wu, Wenqiang Qin, Daoqian Yu, Zhongying Ren, Yi Li, Lingling Wang, Fuguang Li, Zuoren Yang
      Calcium signaling regulates many developmental processes in plants. Calmodulin (CaM) is one of the most conserved calcium sensors and has a flexible conformation in eukaryotes. The molecular functions of CaM are unknown in cotton, which is a major source of natural fiber. In this study, a Gossypium hirsutum L.CaM7-like gene was isolated from upland cotton. Bioinformatics analysis indicated that the GhCaM7 -like gene was highly conserved as compared with Arabidopsis AtCaM7. The GhCaM7 -like gene showed a high expression level in elongating fibers. Expression of β-glucuronidase was observed in trichomes on the stem, leaf and root in transgenic Arabidopsis plants of a PRO GhCaM7-like :GUS fusion. Silencing of the GhCaM7- like gene resulted in decreased fiber length, but also caused reduction in stem height, leaf dimensions, seed length and 100-seed weight, in comparison with those of the control. Reduced expression of the GhCaM7-like gene caused decreased Ca2+ influx in cells of the leaf hypodermis and stem apex, and down-regulation of GhIQD1 (IQ67-domain containing protein), GhAnn2 (Annexins) and GhEXP2 (Expansin). These results indicate that the GhCaM7 -like gene plays a vital role in calcium signaling pathways, and may regulate cotton fiber elongation and biomass production by affecting Ca2+ signatures and downstream signaling pathways of CaM.

      PubDate: 2016-09-25T09:15:02Z
       
  • Proteomic comparison of near-isogenic barley (Hordeum vulgare L.)
           germplasm differing in the allelic state of a major senescence QTL
           identifies numerous proteins involved in plant pathogen defense
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Katelyn E. Mason, Jonathan K. Hilmer, Walid S. Maaty, Benjamin D. Reeves, Paul A. Grieco, Brian Bothner, Andreas M. Fischer
      Senescence is the last developmental phase of plant tissues, organs and, in the case of monocarpic senescence, entire plants. In monocarpic crops such as barley, it leads to massive remobilization of nitrogen and other nutrients to developing seeds. To further investigate this process, a proteomic comparison of flag leaves of near-isogenic late- and early-senescing barley germplasm was performed. Protein samples at 14 and 21 days past anthesis were analyzed using both two-dimensional gel-based and label-free quantitative mass spectrometry-based (‘shotgun’) proteomic techniques. This approach identified >9000 barley proteins, and one-third of them were quantified. Analysis focused on proteins that were significantly (p < 0.05; difference ≥1.5-fold) upregulated in early-senescing line ‘10_11’ as compared to late-senescing variety ‘Karl’, as these may be functionally important for senescence. Proteins in this group included family 1 pathogenesis-related proteins, intracellular and membrane receptors or co-receptors (NBS-LRRs, LRR-RLKs), enzymes involved in attacking pathogen cell walls (glucanases), enzymes with possible roles in cuticle modification, and enzymes involved in DNA repair. Additionally, proteases and elements of the ubiquitin-proteasome system were upregulated in line ‘10_11’, suggesting involvement of nitrogen remobilization and regulatory processes. Overall, the proteomic data highlight a correlation between early senescence and upregulated defense functions. This correlation emerges more clearly from the current proteomic data than from a previously performed transcriptomic comparison of ‘Karl’ and ‘10_11’. Our findings stress the value of studying biological systems at both the transcript and protein levels, and point to the importance of pathogen defense functions during developmental leaf senescence.
      Graphical abstract image

      PubDate: 2016-09-25T09:15:02Z
       
  • Responses of photosynthesis, nitrogen and proline metabolism to salinity
           stress in Solanum lycopersicum under different levels of nitrogen
           supplementation
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Madhulika Singh, Vijay Pratap Singh, Sheo Mohan Prasad
      In the present study, effect of different levels of nitrogen (N0, deprived; N25, sub-optimum; N75, optimum and N150, supra-optimum) in Solanum lycopersicum L. seedlings under NaCl (NaCl1, 0.3 g kg−1 sand and NaCl2, 0.5 g kg−1sand) stress was investigated. Biomass accumulation, pigments, K+ concentration, nitrate and nitrite contents were declined by NaCl in dose dependent manner. As compared to control (N75 without NaCl), fresh weight declined by 4% and 11%, and dry weight by 7 and 13% when seedlings were grown under N75+NaCl1 and N75+NaCl2 combinations, respectively. Furthermore, fluorescence parameters (JIP-test): the size and number of active reaction centres of photosynthetic apparatus (Fv/F0), efficiency of water splitting complex (F0/Fv), quantum yield of primary photochemistry (φP0 or Phi_P0), yield of electron transport per trapped excitation (Ψ0 or Psi_0), the quantum yield of electron transport (φE0), and performance index of PS II (PIABS) and parameters related to energy fluxes per reaction centre (ABS/RC, TR0/RC, ET0/RC and DI0/RC) were also affected by NaCl. However, toxic effect of NaCl on photosystem II photochemistry was ameliorated by N. The lower dose (NaCl1) of NaCl exerts damaging effect on oxidation side of PS II, while higher dose (NaCl2) damages PS II reaction centre and its reduction side. Moreover, control seedlings (N75 without NaCl) when exposed to NaCl1 and NaCl2 exhibited a significant enhancement in respiration rate by 6 and 16%, Na+ accumulation by 111 and 169% in shoot, and 141 and 223% in root and ammonium contents by 19 and 34% respectively. Nitrate and ammonium assimilating enzymes such as nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) and glutamate synthase (GOGAT) were adversely affected by NaCl stress while glutamate dehydrogenase (GDH) showed reverse trend. N addition caused further enhancement in free proline, and activity of Δ1-pyrroline-5-carboxylate synthetase (P5CS), while activity of proline dehydrogenase (ProDH) decreased. The results indicate that different levels of N significantly modulated NaCl-induced damaging effects in tomato seedlings. Furthermore, the results suggest that after N addition Na+, nitrite, nitrate, ammonium contents, nitrogen metabolic enzymes, proline content, and activity of P5CS are favourably regulated, which might be associated with mitigation of NaCl stress and effect was more pronounced with supra-optimum level of N (N150).

      PubDate: 2016-09-21T09:11:31Z
       
  • Malbec grape (Vitis vinifera L.) responses to the environment: Berry
           phenolics as influenced by solar UV-B, water deficit and sprayed abscisic
           acid
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Rodrigo Alonso, Federico J. Berli, Ariel Fontana, Patricia Piccoli, Rubén Bottini
      High-altitude vineyards receive elevated solar ultraviolet-B (UV-B) levels so producing high quality berries for winemaking because of induction in the synthesis of phenolic compounds. Water deficit (D) after veraison, is a commonly used tool to regulate berry polyphenols concentration in red wine cultivars. Abscisic acid (ABA) plays a crucial role in the acclimation to environmental factors/signals (including UV-B and D). The aim of the present study was to evaluate independent and interactive effects of high-altitude solar UV-B, moderate water deficit and ABA applications on Vitis vinifera cv. Malbec berries. The experiment was conducted during two growing seasons with two treatments of UV-B (+UV-B and –UV-B), watering (+D and –D) and ABA (+ABA and –ABA), in a factorial design. Berry fresh weight, sugar content, fruit yield, phenolic compounds profile and antioxidant capacity (ORAC) were analyzed at harvest. Previous incidence of high UV-B prevented deleterious effects of water deficit, i.e. berry weight reduction and diminution of sugar accumulation. High UV-B increased total phenols (mainly astilbin, quercetin and kaempferol) and ORAC, irrespectively of the combination with other factors. Fruit yield was reduced by combining water deficit and high UV-B or water deficit and ABA. Two applications of ABA were enough to induced biochemical changes increasing total anthocyanins, especially those with higher antioxidant capacity.
      Graphical abstract image

      PubDate: 2016-09-21T09:11:31Z
       
  • Role of sugars under abiotic stress
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Fareen Sami, Mohammad Yusuf, Mohammad Faizan, Ahmad Faraz, Shamsul Hayat
      Sugars are the most important regulators that facilitate many physiological processes, such as photosynthesis, seed germination, flowering, senescence, and many more under various abiotic stresses. Exogenous application of sugars in low concentration promote seed germination, up regulates photosynthesis, promotes flowering, delayed senescence under various unfavorable environmental conditions. However, high concentration of sugars reverses all these physiological process in a concentration dependent manner. Thus, this review focuses the correlation between sugars and their protective functions in several physiological processes against various abiotic stresses. Keeping in mind the multifaceted role of sugars, an attempt has been made to cover the role of sugar-regulated genes associated with photosynthesis, seed germination and senescence. The concentration of sugars determines the expression of these sugar-regulated genes. This review also enlightens the interaction of sugars with several phytohormones, such as abscisic acid, ethylene, cytokinins and gibberellins and its effect on their biosynthesis under abiotic stress conditions.

      PubDate: 2016-09-16T09:07:12Z
       
  • Overexpression of a glyoxalase gene, OsGly I, improves abiotic stress
           tolerance and grain yield in rice (Oryza sativa L.)
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Zhengming Zeng, Fangjie Xiong, Xiaohong Yu, Xiaoping Gong, Juntao Luo, Yudong Jiang, Haochi Kuang, Bijun Gao, Xiangli Niu, Yongsheng Liu
      Glyoxalase I (Gly I) is a component of the glyoxalase system which is involved in the detoxification of methylglyoxal, a byproduct of glycolysis. In the present study, a gene of rice (Oryza sativa L., cv. Nipponbare) encoding Gly I was cloned and characterized. The quantitative real-time PCR analysis indicated that rice Gly I (OsGly I) was ubiquitously expressed in root, stem, leaf, leaf sheath and spikelet with varying abundance. OsGly I was markedly upregulated in response to NaCl, ZnCl2 and mannitol in rice seedlings. For further functional investigation, OsGly I was overexpressed in rice using Agrobacterium-mediated transformation. Transgenic rice lines exhibited increased glyoxalase enzyme activity, decreased methylglyoxal level and improved tolerance to NaCl, ZnCl2 and mannitol compared to wild-type plants. Enhancement of stress tolerance in transgenic lines was associated with reduction of malondialdehyde content which was derived from cellular lipid peroxidation. In addition, the OsGly I-overexpression transgenic plants performed higher seed setting rate and yield. Collectively, these results indicate the potential of bioengineering the Gly I gene in crops.

      PubDate: 2016-09-16T09:07:12Z
       
  • NtPHYB1K326, a homologous gene of Arabidopsis PHYB, positively regulates
           the content of phenolic compounds in tobacco
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Jiehong Zhao, Jie Han, Jie Zhang, Zhenhua Li, Jing Yu, Shizhou Yu, Yushuang Guo, Yongfu Fu, Xiaomei Zhang
      Polyphenols are important secondary metabolites and bioactive compounds in plants. Light is a vital abiotic factor that greatly impacts the content of polyphenols in plants. In spite of their importance the mechanism of polyphenol regulation still remains unknown in tobacco. A phytochrome B homolog, NtPHYB1 K326 , was isolated from Nicotiana tabacum cv. K326 to investigate the role of light receptors in the regulation of polyphenol metabolism in tobacco leaves. Furthermore, role of NtPHYB1 K326 in polyphenol metabolism was analyzed by over-expression and RNAi-silencing approaches. Consistent and complemented results indicated involvement of NtPHYB1 K326 in the regulation of polyphenol metabolism in tobacco leaves. Moreover, high levels of NtPHYB1 K326 transcripts favor the accumulation of chlorogenic acid and its isomers, the key polyphenol component in tobacco leaves. Transcriptome analysis was also carried out for exploring the regulation mechanism of NtPHYB1 K326 in the polyphenol metabolism. Compared with WT, 1665 and 1421 differentially-expressed genes were found in NtPHYB1 K326 -GFP and NtPHYB1 K326 -RNAi transgenic lines, respectively. Among these, about 30 genes were related to phenylpropanoid pathway, which is predominantly involved in synthesis of polyphenols. Further evidences from quantitative RT-PCR confirmed that NtPHYB1 K326 may control phenylpropanoid pathway through regulating the transcription of PAL4 (phenylalanine ammonialyase 4), 4CL1 (4-coumarate:coenzyme A ligase 1) and COMT (caffeic acid 3-O-methyltransferase) genes.

      PubDate: 2016-09-16T09:07:12Z
       
  • Generous hosts: What makes Madagascar periwinkle (Catharanthus roseus) the
           perfect experimental host plant for fastidious bacteria'
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Nabil Killiny
      Although much attention has been paid to the metabolism and biosynthesis of monoterpene alkaloids in Catharanthus roseus, its value as an experimental host for a variety of agriculturally and economically important phytopathogenic bacteria warrants further study. In the present study, we evaluated the chemical composition of the phloem and xylem saps of C. roseus to infer the nutritional requirements of phloem- and xylem-limited phytopathogens. Periwinkle phloem sap consisted of a rich mixture of sugars, organic acids, amino acids, amines, fatty acids, sugar acids and sugar alcohols while xylem contained similar compounds in lesser concentrations. Plant sap analysis may lead to a better understanding of the biology of fastidious Mollicutes and their complex nutritional requirements, and to successful culture of phytoplasmas and other uncultured phloem-restricted bacteria such as Candidatus Liberibacter asiaticus, the causal agent of huanglongbing in citrus.

      PubDate: 2016-09-11T08:50:25Z
       
  • The involvement of ROS producing aldehyde oxidase in plant response to
           Tombusvirus infection
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Timur M. Yergaliyev, Zhadyrassyn Nurbekova, Gulzhamal Mukiyanova, Alua Akbassova, Maxim Sutula, Sayan Zhangazin, Assyl Bari, Zhanerke Tleukulova, Malika Shamekova, Zhaksylyk K. Masalimov, Rustem T. Omarov
      The influence of Tomato bushy stunt virus (TBSV) infection on the activity and isoformic composition of aldehyde oxidase and catalase in Nicotiana benthamiana plants was investigated. It was shown that the infection of plants with TBSV results in enhancement of leaf aldehyde oxidase (AO) isoforms AO2 and AO3. Significantly enhanced levels of superoxide radical producing activity of AO isoforms were also detected. This is the first demonstration of involvement of plant AO in defense mechanisms against viral infection. In addition, the infection caused an increased accumulation of hydrogen peroxide, compared to mock-inoculated plants. The virus infection resulted in increased activity of catalase (CAT) and superoxide dismutase (SOD) in roots and leaves of N. benthamiana. Moreover, activation of two additional CAT isoforms was observed in the leaves of plants after virus inoculation. Our findings indicate that the virus infection significantly affects enzymes responsible for the balance of ROS accumulation in plant tissue in response to pathogen attack.

      PubDate: 2016-09-11T08:50:25Z
       
  • Long- and short-term effects of boron excess to root form and function in
           two tomato genotypes
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Maria Polsia Princi, Antonio Lupini, Caterina Longo, Anthony J. Miller, Francesco Sunseri, Maria Rosa Abenavoli
      Boron (B) is an essential plant nutrient, but when present in excess it is toxic. Morphological measurements were made to assess the impact of B toxicity on the growth of two different tomato hybrids, Losna and Ikram. Contrasting long and short-term B responses in these tomato hybrids, were observed. Losna showed less toxicity symptoms, maintaining higher growth and showing much less B content in both root and shoot tissues compared to Ikram. Root morphological differences did not explain the tolerance between the two hybrids. Under excess B supply, a significant inhibition on net nitrate uptake rate was observed in Ikram, but not in Losna. This effect may be explained by a decrease of nitrate transporter transcripts in Ikram, which was not measured in Losna. There was a different pattern of B transporter expression in two tomatoes and this can explain the contrasting tolerance observed. Indeed, Losna may be able to exclude or efflux B resulting in less accumulation in the shoot. Particularly, SlBOR4 expression showed significant differences between the tomato hybrids, with higher expression in Losna explaining the improved B-tolerance.

      PubDate: 2016-09-11T08:50:25Z
       
  • Overexpression of CuZnSOD and APX enhance salt stress tolerance in sweet
           potato
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Hui Yan, Qiang Li, Sung-Chul Park, Xin Wang, Ya-ju Liu, Yun-gang Zhang, Wei Tang, Meng Kou, Dai-fu Ma
      Abiotic stresses cause accumulation of reactive oxygen species (ROS) in plants, CuZnSOD and APX are first line defenses against ROS caused by oxidative stress. In this study, CuZnSOD and APX were transferred into salt sensitive sweet potato (cv. Xushu 55–2) under control of stress inducible SWPA2 promoter and tolerance to salt stress was evaluated. When 100 mM NaCl was used to treat stem cuttings, transgenic plants showed enhanced tolerance compared to wild type (WT) plants. Rooting was significantly retarded in WT plants whereas all transgenic plants had significantly enhanced root growth under salt stress. Integration of SOD gene was confirmed by southern blot analysis, and the copy number ranged from 1 to 3. The expression levels of CuZnSOD and APX in transgenic plants were significantly increased up to 13.3 and 7.8 folds to WT under salinity conditions, respectively. SOD and APX activity and ROS staining showed enzyme activities of transgenic plants were increased under salt stress. These results show that CuZnSOD and APX have important roles in enhancing the salt tolerance of sweet potato.

      PubDate: 2016-09-11T08:50:25Z
       
  • Cloning and characterization of TaMBD6 homeologues encoding
           methyl-CpG-binding domain proteins in wheat
    • Abstract: Publication date: December 2016
      Source:Plant Physiology and Biochemistry, Volume 109
      Author(s): Ruijie Shi, Jiahui Zhang, Jingyuan Li, Ketao Wang, Haiying Jia, Lin Zhang, Putong Wang, Jun Yin, Fanrong Meng, Yongchun Li
      DNA methylation is a major epigenetic marker in plants that plays a crucial role in transcriptional and developmental regulation. The DNA methylation ‘code’ is thought to be ‘read’ by a set of proteins containing methyl-CpG-binding domain (MBD). However, little is known about MBD genes in common wheat (Triticum aestivum L.). Here, we report the isolation and characterization of TaMBD6 and its homeologues (TaMBD6_A, TaMBD6_B, and TaMBD6_D) in hexaploid wheat. The cDNA was quite different among the three homeologues and InDel mutations were detected in 5′-UTR and coding region. Two types of TRs (tandem repeats) -- TR1 (57 bp) and TR2 (39 bp) -- occurred in the coding region. TaMBD6_B harbored five copies of TR1 and two copies of TR2. In contrast, TaMBD6_A lacked 30 bp between the 2nd and 3rd copy of TR1, while TaMBD6_D was missing two copies of TR1 but had three copies of TR2. TaMBD6_A, TaMBD6_B, and TaMBD6_D encoded 435, 446, and 420 amino acids, respectively. Structural analysis of TaMBD6 protein indicated that each of the three homeologues had an identical MBD domain at the N-terminal, as well as a typical nuclear localization signal. Although genomics analysis showed that two introns were included, the length of the first intron varied from 3100 bp to 3471 bp and their sequences were very different. Expression analysis demonstrated that the transcription level of TaMBD6 began to increase gradually in developing grains at 15 days after pollination while decreasing significantly in endosperm and embryo tissues during germination. Expression of TaMBD6 appeared to be positively correlated with starch metabolism in the endosperm but was negatively correlated with embryo formation and sprouting. We were also interested to learn that TaMBD6 homeologues were differentially expressed in developing wheat plants and that their expression patterns were variously affected by vernalization treatment. Further investigation revealed that TaMBD6 was induced by prolonged chilling, indicating that the protein is potentially involved in regulating the developmental transition from vegetative to reproductive stages. Although the homeologues generally showed similar differential expression patterns, TaMBD6_D and TaMBD6_B contribute more to the processes of grain development and germination while TaMBD6_A is predominant in mature plants.

      PubDate: 2016-09-11T08:50:25Z
       
  • Nickel tolerance, accumulation and subcellular distribution in the
           halophytes Sesuvium portulacastrum and Cakile maritima
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Emna Fourati, Mariem Wali, Katarina Vogel-Mikuš, Chedly Abdelly, Tahar Ghnaya
      It has been shown that halophytes are able to successfully cope with heavy metal toxicity, suggesting their possible use for remediation of metal contaminated soils. In this work, Ni tolerance and accumulation in two halophytes, Sesuvium portulacastrum (L.) L. and Cakile maritima Scop. was investigated. Seedlings of both species were subjected hydroponically during 21 days to 0, 25, 50, and 100 μM of NiCl2. The growth and photosynthesis parameters revealed that S. portulacastrum tolerates Ni better than C. maritima. The photosynthesis activity, chlorophyll content and photosystem II integrity were less impacted in Ni-treated S. portulacastrum as compared to C. maritima, although, Ni accumulated in higher concentrations in the shoots of S. portulacastrum (1050 μg g−1 DW) than in those of C. maritima (550 μg g−1 DW). The subcellular fractionation of Ni in the shoots of both species showed that C. maritima accumulated about 65% of Ni in the soluble fraction, while 28% was associated with the cell walls. In S. portulacastrum 44% of the total cellular Ni was seen in the soluble fraction and 43% was bound to the cell walls. It can be concluded that S. portulacastrum tolerates Ni better than C. maritima, most probably due to a better ability to sequester Ni in the cell walls, restricting its accumulation in the soluble fraction.

      PubDate: 2016-08-04T07:12:21Z
       
  • Interactive effects of phosphorus and Pseudomonas putida on chickpea
           (Cicer arietinum L.) growth, nutrient uptake, antioxidant enzymes and
           organic acids exudation
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Dania Israr, Ghulam Mustafa, Khalid Saifullah Khan, Muhammad Shahzad, Niaz Ahmad, Sajid Masood
      Phosphorus (P) availability in alkaline soils of arid and semi-arid regions is a major constraint for decreased crop productivity. Use of plant growth promoting rhizobacteria (PGPR) may enhance plant growth through the increased plant antioxidation activity. Additionally, PGPR may increase nutrient uptake by plants as a result of induced root exudation and rhizosphere acidification. The current study was aimed to investigate combined effects of P and Pesudomonas putida (PGPR) on chickpea growth with reference to antioxidative enzymatic activity and root exudation mediated plant nutrient uptake, particularly P. Half of the seeds were soaked in PGPR solution, whereas others in sterile water and latter sown in soils. Plants were harvested 8 weeks after onset of experiment and analyzed for leaf nutrient contents, antioxidant enzymes activities and organic acids concentrations. Without PGPR, P application (+P) increased various plant growth attributes, plant uptake of P and Ca, soil pH, citric acid and oxalic acid concentrations, whereas decreased the leaf POD enzymatic activity as compared to the P-deficiency. PGPR supply both under −P and +P improved the plant growth, plant uptake of N, P, and K, antioxidative activity of SOD and POD enzymes and concentrations of organic acids, whereas reduced the rhizosphere soil pH. Growth enhancement by PGPR supply was related to higher plant antioxidation activity as well as nutrient uptake of chickpea including P as a result of root exudation mediated rhizosphere acidification.

      PubDate: 2016-08-04T07:12:21Z
       
  • Phosphorylation of phosphoenolpyruvate carboxykinase (PEPCK) and
           phosphoenolpyruvate carboxylase (PEPC) in the flesh of fruits
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Robert P. Walker, Andrea Paoletti, Richard C. Leegood, Franco Famiani
      This study determined whether phosphoenolpyruvate carboxykinase (PEPCK) and phosphoenolpyruvate carboxylase (PEPC) are phosphorylated in the flesh of a range of fruits. This was done by incubating fruit flesh with 32P[P] (where 32P[P] = 32PO4 3−), then PEPCK and PEPC were immunoprecipitated from extracts using specific antisera. The incorporation of 32P[P] into these enzymes was then determined by autoradiography of SDS-PAGE gels. Both enzymes were subject to phosphorylation in vivo in the flesh of grape, tomato, cherry and plum. PEPCK was also subject to phosphorylation in vivo in developing grape seeds. Proteolytic cleavage of PEPCK showed that it was phosphorylated at a site(s) located on its N-terminal extension. Potentially phosphorylation of these enzymes could contribute to the coordinate regulation of their activities in the flesh of fruits and in developing seeds.

      PubDate: 2016-08-04T07:12:21Z
       
  • Effects of growth temperature and carbon dioxide enrichment on soybean
           seed components at different stages of development
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Guangli Xu, Shardendu Singh, Jinyoung Barnaby, Jeffrey Buyer, Vangimalla Reddy, Richard Sicher
      Soybean plants were grown to maturity in controlled environment chambers and at the onset of flowering three temperature treatments were imposed that provided optimum [28/24 °C], low [22/18 °C] or high [36/32 °C] chamber air temperatures. In addition, plants were treated continuously with either 400 or 800 μmol mol−1 CO2. Seeds were harvested at 42, 53, 69 and 95 days after planting (i.e., final maturity). This study quantified 51 metabolites in developing soybean seeds, plus total lipids and proteins were measured at maturity. About 80% of measured soluble carbohydrates, amines and organic acids decreased to low levels in mature seeds, although important exceptions were raffinose, ribose/arabinose, citrate and all eight fatty acids. This suggested that the metabolism of young seeds supported lipid and protein synthesis. A total of 35 and 9 metabolites differed among temperature and CO2 treatments, respectively, and treatment effects were predominately observed on the first and second samplings. However, shikimate, pinitol and oleate were increased by high temperature treatments in mature seeds. The above results indicated that CO2 enrichment primarily altered metabolite levels during the initial stages of seed development and this was likely due to enhanced photosynthate formation in leaves.
      Graphical abstract image

      PubDate: 2016-08-04T07:12:21Z
       
  • Identification and validation of reference genes for quantitative
           real-time PCR studies in Hedera helix L.
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Hua-peng Sun, Fang Li, Qin-mei Ruan, Xiao-hong Zhong
      Reference gene evaluation and selection are necessary steps in gene expression analysis, especially in new plant varieties, through reverse transcription quantitative real-time PCR (RT-qPCR). Hedera helix L. is an important traditional medicinal plant recorded in European Pharmacopoeia. Research on gene expression in H. helix has not been widely explored, and no RT-qPCR studies have been reported. Thus, it is important and necessary to identify and validate suitable reference genes to for normalizing RT-qPCR results. In our study, 14 candidate protein-coding reference genes were selected. Their expression stability in five tissues (root, stem, leaf, petiole and shoot tip) and under seven abiotic stress conditions (cold, heat, drought, salinity, UV-C irradiation, abscisic acid and methyl jasmonate) were evaluated using geNorm and NormFinder. This study is the first to evaluate the stability of reference genes in H. helix. The results show that different reference genes should be chosen for normalization on the basis of various experimental conditions. F-box was more stable than the other selected genes under all analysis conditions except ABA treatment; 40S was the most stable reference gene under ABA treatment; in contrast, EXP and UBQ were the most unstable reference genes. The expressions of HhSE and Hhβ-AS, which are two genes related to the biosynthetic pathway of triterpenoid saponins, were also examined for reference genes in different tissues and under various cold stress conditions. The validation results confirmed the applicability and accuracy of reference genes. Additionally, this study provides a basis for the accurate and widespread use of RT-qPCR in selecting genes from the genome of H. helix.

      PubDate: 2016-07-29T06:30:45Z
       
  • RPN1a negatively regulates ABA signaling in Arabidopsis
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Dashi Yu, Xiushan Li, Xiaoying Zhao, Changqing Du, Jia Chen, Chiyu Li, Mengsi Sun, Long Wang, Jianzhong Lin, Dongying Tang, Feng Yu, Xuanming Liu
      The 26S proteasome selectively regulates key abscisic acid (ABA) signaling proteins, but the physiological functions and mechanisms of RPN1a (a subunit of the 26S proteasome) in ABA signaling remain largely unknown. In this study, we found that the mRNA expression of RPN1a was suppressed by ABA treatment, and that RPN1a protein was expressed abundantly in guard cells. In the presence of ABA, rpn1a mutants showed rapid stomatal closure, low water loss, delayed germination, and inhibited root elongation. In addition, the transcripts of key ABA signaling genes, including ABI5, RD22, RD29A, and RD29B, were upregulated in rpn1a mutant plants in response to ABA. Furthermore, the ABI5 protein level was higher in rpn1a mutants subjected to ABA treatment. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that RPN1a interacts with ABI1. Overall, these findings suggest that RPN1a negatively regulates ABA signaling in Arabidopsis.

      PubDate: 2016-07-29T06:30:45Z
       
  • Osmotic stress alters UV-based oxidative damage tolerance in a heterocyst
           forming cyanobacterium
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Germán Pérez, Soledad Doldán, Paola Scavone, Omar Borsani, Pilar Irisarri
      Cyanobacteria are successful in diverse habitats due to their adaptation strategies. Their mechanisms to cope with individual stresses have been studied. However, the response to combined stress conditions as found in nature remains unclear. With this aim, we studied the dual effect of 24h-osmotic and 3h-UV irradiation on the cyanobacterium Calothrix BI22. Our approach included the study of redox homeostasis, oxidative damage, reactive oxygen species production-consumption processes and photosynthetic activity. Superoxide in vivo determination with confocal image processing showed the highest accumulation under UV. However, no lipoperoxidation occurred due to a high SOD activity. This cyanobacterium was less prepared to cope with the osmotic stress assayed. Under this condition, O2 photoevolution decreased abruptly and oxidative damage was produced by reactive species other than superoxide. In this situation the cellular control of the amount of ROS failed to prevent oxidative damage and photosynthesis was seriously disturbed in spite of maximum quantum photosynthetic efficiency remained unchanged. Calothrix BI22 presented the more severe oxidative damage when both stressors were applied. The osmotic stress disentangled the mechanisms developed by this cyanobacterium to deal with 3h-UV irradiation alone.

      PubDate: 2016-07-29T06:30:45Z
       
  • Comparison of polyamine metabolism in tomato plants exposed to different
           concentrations of salicylic acid under light or dark conditions
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Zoltán Takács, Péter Poór, Irma Tari
      In this study the effect of exogenous 0.1 mM and 1 mM salicylic acid (SA) treatments were investigated on polyamine (PA) metabolism in tomato (Solanum lycopersicum L. cv. Ailsa Craig) leaves in illuminated or dark environments. The former proved to be sublethal and the latter lethal concentration for tomato leaf tissues. While PA biosynthetic genes, arginine- and ornitine decarboxylases or spermidine- and spermine synthases were highly up-regulated by 1 mM SA, the enzymes participating in PA catabolism, diamine- (DAOs, EC 1.4.3.6) and polyamine oxidases (PAOs, EC 1.5.3.3) displayed higher transcript abundance and enzyme activity at 0.1 mM SA. As a result, putrescine and spermine content but not that of spermidine increased after 1 mM SA application, which proved to be higher in the dark than in the light. H2O2 content produced on the effect of 1 mM SA was significantly higher than at 0.1 mM SA in the light. Since there was no coincidence between H2O2 accumulation and terminal PA catabolism, reactive oxygen species produced by photosynthesis and by other sources had more pronounced effect on H2O2 generation at tissue level than DAOs and PAOs. Accordingly, H2O2 in the absence of NO accumulation contributed to the initiation of defence reactions after 0.1 mM SA treatment, while high SA concentration generated simultaneous increase in H2O2 and NO production in the light, which induced cell death within 24 h in illuminated leaves. However, the appearance of necrotic lesions was delayed in the absence of NO if these plants were kept in darkness.

      PubDate: 2016-07-29T06:30:45Z
       
  • Genome-wide analysis of the fructose 1,6-bisphosphate aldolase (FBA) gene
           family and functional characterization of FBA7 in tomato
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Bingbing Cai, Qiang Li, Yongchao Xu, Long Yang, Huangai Bi, Xizhen Ai
      Fructose 1,6-bisphosphate aldolase (FBA) is a key enzyme in plants that is involved in glycolysis, gluconeogenesis, and the Calvin cycle. FBA genes play significant roles in biotic and abiotic stress responses and also regulate growth and development. Despite the importance of FBA genes, little is known about it in tomato. In this study, we identified 8 FBA genes in tomato and classified them into 2 subgroups based on a phylogenetic tree, gene structures, and conserved motifs. Five (SlFBA1, 2, 3, 4 and 5) and three (SlFBA6, 7, and 8) SlFBA proteins were predicted to be localized in chloroplasts and cytoplasm, respectively. The phylogenetic analysis of FBAs from tomato, Arabidopsis, rice, and other organisms suggested that SlFBA shared the highest protein homology with FBAs from other plants. Synteny analysis indicated that segmental duplication events contributed to the expansion of the tomato FBA family. The expression profiles revealed that all SlFBAs were involved in the response to low and high temperature stresses. SlFBA7 overexpression increased the expression and activities of other main enzymes in Calvin cycle, net photosynthetic rate (Pn), seed size and stem diameter. SlFBA7 overexpression enhanced tolerances in seed germination under suboptimal temperature stresses. Taken together, comprehensive analyses of SlFBAs would provide a basis for understanding of evolution and function of SlFBA family.

      PubDate: 2016-07-29T06:30:45Z
       
  • Molecular cloning and functional characterization of DkMATE1 involved in
           proanthocyanidin precursor transport in persimmon (Diospyros kaki Thunb.)
           fruit
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Sichao Yang, Yun Jiang, Liqing Xu, Katsuhiro Shiratake, Zhengrong Luo, Qinglin Zhang
      Persimmon fruits accumulate a large amount of proanthocyanidins (PAs) in “tannin cells” during development that cause the sensation of astringency due to coagulation of oral proteins. Pollination-constant non-astringent (PCNA) is a spontaneous mutant persimmon phenotype that loses its astringency naturally on the tree at maturity; while the more common non-PCNA fruits remain rich in PAs until they are fully ripened. Here, we isolated a DkMATE1 gene encoding a Multidrug And Toxic Compound Extrusion (MATE) family protein from the Chinese PCNA (C-PCNA) ‘Eshi 1’. Expression patterns of DkMATE1 were positively correlated with the accumulation of PAs in different types of persimmons fruits during fruit development. An analysis of the inferred amino acid sequences and phylogenetic relationships indicated that DkMATE1 is a putative PA precursor transporter, and subcellular localization assays revealed that DkMATE1 is localized in the vacuolar membrane. Ectopic expression of the DkMATE1 in Arabidopsis tt12 mutant supported that DkMATE1 could complement its biological function in transporting epicatechin 3′-O-glucoside as a PAs precursor from the cytoplasm to vacuole. Furthermore, the transient over-expression and silencing of DkMATE1 in ‘Mopanshi’ persimmon leaves resulted in a significant increase and a decrease in PA content, respectively. The analysis of cis-elements in DkMATE1 promoter regions indicated that DkMATE1 might be regulated by DkMYB4, another well-known structural gene in persimmon. Overall, our results show that DkMATE1 may be an essential PA precursor membrane transporter that plays an important role in PA biosynthesis in persimmon.

      PubDate: 2016-07-29T06:30:45Z
       
  • Effect of nitrogen deficiency on ascorbic acid biosynthesis and recycling
           pathway in cucumber seedlings
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Xue Zhang, Hong Jun Yu, Xiao Meng Zhang, Xue Yong Yang, Wen Chao Zhao, Qiang Li, Wei Jie Jiang
      L-Ascorbic acid (AsA, ascorbate) is one of the most abundant natural antioxidants, and it is an important factor in the nutritional quality of cucumber. In this work, key enzymes involved in the ascorbic acid biosynthesis and recycling pathway in cucumber seedlings under nitrogen deficiency were investigated at the levels of transcription and enzyme activity. The activities of myo-inositol oxygenase (MIOX) and transcript levels of MIOXs increased dramatically, while the activities of ascorbate oxidase (AO) and glutathione reductase (GR) and transcript levels of AOs and GR2 decreased significantly in N-limited leaves, as did the ascorbate concentration, in nitrogen-deficient cucumber seedlings. The activities of other enzymes and transcript levels of other genes involved in the ascorbate recycling pathway and ascorbate synthesis pathways decreased or remained unchanged under nitrogen deficiency. These results indicate that nitrogen deficiency induced genes involved in the ascorbate-glutathione recycling and myo-inositol pathway in cucumber leaves. Thus, the AO, GR and MIOX involved in the pathways might play roles in AsA accumulation.

      PubDate: 2016-07-29T06:30:45Z
       
  • Silybin content and overexpression of chalcone synthase genes in Silybum
           marianum L. plants under abiotic elicitation
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Hoda A.S. El-Garhy, Salah Khattab, Mahmoud M.A. Moustafa, Rania Abou Ali, Ahmed Z. Abdel Azeiz, Abeer Elhalwagi, Fadia El Sherif
      Silymarin, a Silybum marianum seed extract containing a mixture of flavonolignans including silybin, is being used as an antihepatotoxic therapy for liver diseases. In this study, the enhancing effect of gamma irradiation on plant growth parameters of S. marianum under salt stress was investigated. The effect of gamma irradiation, either as a single elicitor or coupled with salinity, on chalcone synthase (CHS) gene expression and silybin A + B yield was also evaluated. The silybin A + B content in S. marianum fruits was estimated by liquid chromatography–mass spectrometry (LC-MS/MS). An increase in silybin content was accompanied by up-regulation of the CHS1, CHS2 and CHS3 genes, which are involved in the silybin biosynthetic pathway. The highest silybin A + B production (0.77 g/100 g plant DW) and transcript levels of the three studied genes (100.2-, 91.9-, and 24.3-fold increase, respectively) were obtained with 100GY gamma irradiation and 4000 ppm salty water. The CHS2 and CHS3 genes were partially sequenced and submitted to the NCBI database under the accession numbers KT252908.1 and KT252909.1, respectively. Developing new approaches to stimulate silybin biosynthetic pathways could be a useful tool to potentiate the use of plants as renewable resources of medicinal compounds.

      PubDate: 2016-07-25T14:31:29Z
       
  • Kinetic commitment in the catalysis of glutamine synthesis by GS1 from
           Arabidopsis using 14N/15N and solvent isotope effects
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Caroline Mauve, Nicolas Giraud, Edouard R.A. Boex-Fontvieille, Ingrid Antheaume, Illa Tea, Guillaume Tcherkez
      Glutamine synthetase (GS, EC 6.3.1.2) catalyzes the production of glutamine from glutamate, ammonium and ATP. Although being essential in plants for N assimilation and recycling, kinetic commitments and transition states of the reaction have not been clearly established yet. Here, we examined 12C/13C, 14N/15N and H2O/D2O isotope effects in Arabidopsis GS1 catalysis and compared to the prokaryotic (Escherichia coli) enzyme. A14N/15N isotope effect (15 V/K ≈ 1.015, with respect to substrate NH4 +) was observed in the prokaryotic enzyme, indicating that ammonium utilization (deprotonation and/or amidation) was partially rate-limiting. In the plant enzyme, the isotope effect was inverse (15 V/K = 0.965), suggesting that the reaction intermediate is involved in an amidation-deamidation equilibrium favoring 15N. There was no 12C/13C kinetic isotope effect (13 V/K = 1.000), suggesting that the amidation step of the catalytic cycle involves a transition state with minimal alteration of overall force constants at the C-5 carbon. Surprisingly, the solvent isotope effect was found to be inverse, that is, with a higher turn-over rate in heavy water (D V ≈ 0.5), showing that restructuration of the active site due to displacement of H2O by D2O facilitates the processing of intermediates.

      PubDate: 2016-07-25T14:31:29Z
       
  • 24-Epibrassinolide ameliorates salt stress effects in the symbiosis
           Medicago truncatula-Sinorhizobium meliloti and regulates the nodulation in
           cross-talk with polyamines
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Miguel López-Gómez, Javier Hidalgo-Castellanos, Carmen Lluch, José A. Herrera-Cervera
      Brassinosteroids (BRs) are steroid plant hormones that have been shown to be involved in the response to salt stress in cross-talk with other plant growth regulators such as polyamines (PAs). In addition, BRs are involved in the regulation of the nodulation in the rhizobium-legume symbiosis through the alteration of the PAs content in leaves. In this work, we have studied the effect of exogenous 24-epibrassinolide (EBL) in the response to salinity of nitrogen fixation in the symbiosis Medicago truncatula-Sinorhizobium meliloti. Foliar spraying of EBL restored the growth of plants subjected to salt stress and provoked an increment of the nitrogenase activity. In general, PAs levels in leaves and nodules decreased by the salt and EBL treatments, however, the co-treatment with NaCl and EBL augmented the foliar spermine (Spm) concentration. This increment of the Spm levels was followed by a reduction of the membrane oxidative damage and a diminution of the proline accumulation. The effect of BRs on the symbiotic interaction was evaluated by the addition of 0.01, 0.1 and 0.5 μM EBL to the growing solution, which provoked a reduction of the nodule number and an increment of the PAs levels in shoot. In conclusion, foliar treatment with EBL had a protective effect against salt stress in the M. truncatula-S. meliloti symbiosis mediated by an increment of the Spm levels. Treatment of roots with EBL incremented PAs levels in shoot and reduced the nodule number which suggests a cross-talk between PAs and BRs in the nodule suppression and the protection against salt stress.

      PubDate: 2016-07-25T14:31:29Z
       
  • Silicon addition to soybean (Glycine max L.) plants alleviate zinc
           deficiency
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): M Blanca Pascual, Virginia Echevarria, M José Gonzalo, Lourdes Hernández-Apaolaza
      It is well established the beneficial role of silicon (Si) in alleviating abiotic stress. However, it remains poorly understood the mechanisms of the Si-mediated protection against metal deficiency, especially the zinc (Zn) one. Recently, it has been proposed that Si may act by an interaction with this biometal in the root apoplast contributing to its movement through the plant, as in the case of Fe deficiency. In the present work, the effect of initial or continuous Si doses in soybean Zn deficient plants has been studied. For that purpose, plants grown in hydroponic culture were treated with different Si doses (0.0, 0.5 and 1.0 mM) under Zn limiting conditions. SPAD index in leaves, several growth parameters, mineral content in the whole plant and the formation of Zn pools in roots were determined. An initial addition of 0.5 mM of Si to the nutrient solution led to an enhancement of plants growth, Zn and Si content in leaves, and a higher storage of Zn in the root apoplast. The results suggest that this treatment enhanced Zn accumulation on roots and its movement to shoots when needed, mitigating Zn deficiency symptoms.

      PubDate: 2016-07-20T14:06:51Z
       
  • Purification of recombinant tissue plasminogen activator (rtPA) protein
           from transplastomic tobacco plants
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Maryam Abdoli Nasab, Mokhtar Jalali Javaran, Rosa M. Cusido, Javier Palazon
      Plants are low cost platforms for the production of recombinant proteins, but their complexity renders the purification of plant recombinant proteins more difficult than proteins expressed in yeast or bacteria. Plastid transformation enables high-level expression of foreign genes and the accumulation of recombinant proteins in plastid organelles. Histidine (His) tags are widely used for affinity purification of recombinant proteins in a nickel column. The human tissue-type plasminogen activator (tPA) is one of the most important pharmaceutical recombinant proteins involved in the breakdown of blood clots in different parts of the body. The truncated form of the tissue plasminogen activator (K2S) has a longer plasma half-life, better diffusion into the clot, and higher fibrinolytic activity. In a construct designed to insert the K2S gene in the tobacco chloroplast, the sequence of six histidines and a factor Xa protease site was fused to the C-terminus of the K2S protein. The presence and amount of tPA recombinant protein in transplastomic tobacco plants was estimated by ELISA analysis using a specific antibody. The protein was purified from total soluble protein, insoluble protein aggregates and the protein was extracted from the isolated chloroplast using nickel resin and a chromatography column. After digestion of the purified protein with factor Xa, the presence of the purified tPA protein was confirmed by western blot analysis.

      PubDate: 2016-07-20T14:06:51Z
       
  • Arabidopsis thaliana MRP1 (AtABCC1) nucleotide binding domain contributes
           to arsenic stress tolerance with serine triad phosphorylation
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Ayan Raichaudhuri
      Multidrug resistance protein AtMRPs belong to the ATP binding cassette (ABC) transporter super family. ABC proteins are membrane proteins involved in the transport of a broad range of amphipathic organic anions across membranes. MRPs (ABCCs) are one of the highly represented subfamilies of ABC transporters. Plant MRPs also transport various glutathione conjugates across membranes. Arabidopsis thaliana MRP1 is already known to be involved in vacuolar storage of folates. Using heterologously expressed AtMRP1 in yeast and its C-terminal nucleotide binding domain (NBD2) in E scherichia coli, it has been shown that Casein kinase II (CKII) mediated phosphorylation is a potential regulator of AtMRP1 function. AtMRP1 showed enhanced tolerance towards arsenite As(III) in yeast. CKIIII/CKII mediated phosphorylation of AtMRP1 was found to be involved in As(III) mediated signaling. AtMRP1-NBD2 and its serine mutants showed distinct change in secondary structure in the presence of arsenite and methotrexate (MTX) controlled by serine triad phosphorylation. Results showed that AtMRP1 is important for vacuolar accumulation of antifolates as well as tolerance against arsenic, both of which involved phosphorylation in the serine triads at the C terminal NBD of AtMRP1. The experiments provide an important insight into the role of AtMRP1 serine triad phosphorylation under AsIII stress conditions.

      PubDate: 2016-07-20T14:06:51Z
       
  • Different metabolite profile and metabolic pathway with leaves and roots
           in response to boron deficiency at the initial stage of citrus rootstock
           growth
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Xiaochang Dong, Guidong Liu, Xiuwen Wu, Xiaopei Lu, Lei Yan, Riaz Muhammad, Asad Shah, Lishu Wu, Cuncang Jiang
      Boron (B) is a microelement required for higher plants, and B deficiency has serious negative effect on metabolic processes. We concentrated on the changes in metabolite profiles of trifoliate orange leaves and roots as a consequence of B deficiency at the initial stage of growth by gas chromatography-mass spectrometry (GC-MS)-based metabolomics. Enlargement and browning of root tips were observed in B-deficient plants, while any obvious symptom was not recorded in the leaves after 30 days of B deprivation. The distinct patterns of alterations in metabolites observed in leaves and roots due to B deficiency suggest the presence of specific organ responses to B starvation. The accumulation of soluble sugars was occurred in leaves, which may be attributed to down-regulated pentose phosphate pathway (PPP) and amino acid biosynthesis under B deficiency, while the amount of most amino acids in roots was increased, indicating that the effects of B deficiency on amino acids metabolism in trifoliate orange may be a consequence of disruptions in root tissues and decreased protein biosynthesis. Several important products of shikimate pathway were also significantly affected by B deficiency, which may be related to abnormal growth of roots induced by B deficiency. Conclusively, our results revealed a global perspective of the discriminative metabolism responses appearing between B-deprived leaves and roots and provided new insight into the relationship between B deficiency symptom in roots and the altered amino acids profiling and shikimate pathway induced by B deficiency during seedling establishment.

      PubDate: 2016-07-20T14:06:51Z
       
  • Genome-wide identification, characterization and expression profiling of
           LIM family genes in Solanum lycopersicum L.
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Khadiza Khatun, Arif Hasan Khan Robin, Jong-In Park, Nasar Uddin Ahmed, Chang Kil Kim, Ki-Byung Lim, Min-Bae Kim, Do-Jin Lee, Ill Sup Nou, Mi-Young Chung
      LIM domain proteins, some of which have been shown to be actin binding proteins, are involved in various developmental activities and cellular processes in plants. To date, the molecular defense-related functions of LIM family genes have not been investigated in any solanaceous vegetable crop species. In this study, we identified 15 LIM family genes in tomato (Solanum lycopersicum L.) through genome-wide analysis and performed expression profiling in different organs of tomato, including fruits at six different developmental stages. We also performed expression profiling of selected tomato LIM genes in plants under ABA, drought, cold, NaCl and heat stress treatment. The encoded proteins of the 15 tomato LIM genes were classified into two main groups, i.e., proteins similar to cysteine-rich proteins and plant-specific DAR proteins, based on differences in functional domains and variability in their C-terminal regions. The DAR proteins contain a so far poorly characterized zinc-finger-like motif that we propose to call DAR-ZF. Six of the 15 LIM genes were expressed only in flowers, indicating that they play flower-specific roles in plants. The other nine genes were expressed in all organs and at various stages of fruit development. SlβLIM1b was expressed relatively highly at the later stage of fruit development, but three other genes, SlWLIM2a, SlDAR2 and SlDAR4, were expressed at the early stage of fruit development. Seven genes were induced by ABA, five by cold, seven by drought, eight by NaCl and seven by heat treatment respectively, indicating their possible roles in abiotic stress tolerance. Our results will be useful for functional analysis of LIM genes during fruit development in tomato plants under different abiotic stresses.

      PubDate: 2016-07-20T14:06:51Z
       
  • Genome-wide identification and domain organization of lectin domains in
           cucumber
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Liuyi Dang, Els J.M. Van Damme
      Lectins are ubiquitous proteins in plants and play important roles in a diverse set of biological processes, such as plant defense and cell signaling. Despite the availability of the Cucumis sativus L. genome sequence since 2009, little is known with respect to the occurrence of lectins in cucumber. In this study, a total of 146 putative lectin genes belonging to 10 different lectin families were identified and localized in the cucumber genome. Domain architecture analysis revealed that most of these lectin gene sequences contain multiple domains, where lectin domains are linked with other domains, as such creating chimeric lectin sequences encoding proteins with dual activities. This study provides an overview of lectin motifs in cucumber and will help to understand their potential biological role(s).

      PubDate: 2016-07-20T14:06:51Z
       
  • The effect of kinetin on wheat seedlings exposed to boron
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Ahmet Eser, Tülin Aydemir
      The objective of this study was to examine relationship between boron (B) induced oxidative stress and antioxidant system in boron sensitive and tolerant wheat cultivars Bezostaya and Kutluk, and also to investigate whether Kinetin (KN) enhances the level of antioxidant system, relative growth, concentration of hydrogen peroxide (H2O2), malondialdehyde (MDA) and proline and chlorophyll content in both cultivars exposed to B stress. B treatments diminished growth and chlorophyll content whereas, it enhanced accumulation of H2O2, MDA and proline, and various antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and lipoxygenase (LOX) in the shoot and root of both cultivars. However, the follow-up application of KN to the B stressed plants improved growth and chlorophyll content and further enhanced the mentioned antioxidant enzymes and level of H2O2, MDA and proline. This study thus suggests that KN improves B tolerance of the studied cultivars grown under B toxicity.

      PubDate: 2016-07-20T14:06:51Z
       
  • Metabolomic profiling of the halophyte Prosopis strombulifera shows sodium
           salt- specific response
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Analía Llanes, Vicent Arbona, Aurelio Gómez-Cadenas, Virginia Luna
      Primary and secondary metabolite profiles were analyzed in roots and leaves of the halophytic shrub Prosopis strombulifera in response to control plants (no salt added in the growing media) and to lowering the osmotic potential to −1.0, −1.9, and −2.6 MPa generated by NaCl, Na2SO4, and the iso-osmotic combination of them at 24 h after reaching such potential. A rapid production of metabolites in response to sodium salt was found, which was correlated with modifications in growth parameters. Analysis of polar metabolite profiles by GC-MS rendered a total of 108 significantly altered compounds including 18 amino acids, 19 secondary metabolites, 23 carbohydrates, 13 organic acids, 4 indole acids, among others. Primary metabolites showed a differential response under the salt treatments, which was dependent on salt type and concentration, organ and age of plants. Most of identified compounds showed the strongest accumulation at the highest salt concentration assayed for Na2SO4-treated plants, which was correlated with damaging effects of sulfate anion on plant growth. Roots of NaCl-treated plants showed a higher number of altered metabolites (analyzed by UPLC-ESI-QqTOF-MS) compared to other treatments, while leaves of Na2SO4-treated plants showed the highest number of altered signals. A low degree of overlapping between secondary metabolites altered in roots and leaves of NaCl and Na2SO4-treated plants was found. However, when both NaCl and Na2SO4 salts were present plants always showed a lower number of altered metabolites. Three compounds were tentatively identified: tryptophan, lysophosphatidylcoline and 13-hydroxyoctadecadienoic acid. Increasing knowledge on P. strombulifera metabolism will contribute to unravel the underlying biochemical mechanism of salt tolerance.
      Graphical abstract image

      PubDate: 2016-07-20T14:06:51Z
       
  • Proteomic analysis of JAZ interacting proteins under methyl jasmonate
           treatment in finger millet
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Saswati Sen, Sangeeta Kundu, Samir Kr. Dutta
      Jasmonic acid (JA) signaling pathway in plants is activated against various developmental processes as well as biotic and abiotic stresses. The Jasmonate ZIM-domain (JAZ) protein family, the key regulator of plant JA signaling pathway, also participates in phytohormone crosstalk. This is the first study revealing the in vivo interactions of finger millet (Eleusine coracana (L.) Gaertn.) JAZ protein (EcJAZ) under methyl jasmonate (MJ) treatment. The aim of the study was to explore not only the JA signaling pathway but also the phytohormone signaling crosstalk of finger millet, a highly important future crop. From the MJ-treated finger millet seedlings, the EcJAZ interacting proteins were purified by affinity chromatography with the EcJAZ-matrix. Twenty-one proteins of varying functionalities were successfully identified by MALDI-TOF-TOF Mass spectrometry. Apart from the previously identified JAZ binding proteins, most prominently, EcJAZ was found to interact with transcription factors like NAC, GATA and also with Cold responsive protein (COR), etc. that might have extended the range of functionalities of JAZ proteins. Moreover, to evaluate the interactions of EcJAZ in the JA-co-receptor complex, we generated ten in-silico models containing the EcJAZ degron and the COI1-SKP1 of five monocot cereals viz., rice, wheat, maize, Sorghum and Setaria with JA-Ile or coronatine. Our results indicated that the EcJAZ protein of finger millet could act as the signaling hub for the JA and other phytohormone signaling pathways, in response to a diverse set of stressors and developmental cues to provide survival fitness to the plant.

      PubDate: 2016-07-16T13:59:19Z
       
  • MYC2, MYC3, and MYC4 function redundantly in seed storage protein
           accumulation in Arabidopsis
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Chenhao Gao, Shuanghui Qi, Kaige Liu, Dong Li, Changyu Jin, Zhuowei Li, Gengqing Huang, Jiangbo Hai, Meng Zhang, Mingxun Chen
      Basic helix-loop-helix transcription factors (TFs), namely MYC2, MYC3, and MYC4, interact with Jasmonate Zim-domain proteins and are their direct targets. These TFs have been shown to function synergistically to control Arabidopsis growth and development. Our results showed similar MYC2, MYC3, and MYC4 expression patterns during Arabidopsis seed development, which remained relatively high during seed mid-maturation. MYC2, MYC3, and MYC4 acted redundantly in seed size, weight control, and in regulating seed storage protein accumulation. Triple mutants produced the largest seeds and single and double mutants’ seeds were much larger than those of wild type. The weight of triple mutants’ seeds was significantly higher than that of wild-type seeds, which was accompanied by an increase in seed storage protein contents. Triple mutants’ seeds presented a marked decrease in 2S amounts relative to those in wild-type seeds. Liquid chromatography tandem mass spectra sequencing results indicated that both the relative abundance and the peptide number of CRA1 and CRU3 were greatly increased in triple mutants compared to wild type. The expression of 2S1–2S5 decreased and that of CRA1 and CRU3 increased in triple mutants relative to those in wild types during seed development, which might have contributed to the low 2S and high 12S contents in triple mutants. Our results contribute to understanding the function of MYC2, MYC3, and MYC4 on seed development, and provide promising targets for genetic manipulations of protein-producing crops to improve the quantity and quality of seed storage proteins.

      PubDate: 2016-07-16T13:59:19Z
       
  • Identification of structural elements involved in fine-tuning of the
           transport activity of the rice ammonium transporter OsAMT1;3
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Dongli Hao, Shunying Yang, Yanan Huang, Yanhua Su
      Ammonium transporters (AMTs) are major routes for plant uptake of the NH4 +-form nitrogen. Plant AMTs mediate predominantly the uptake of NH4 + and to a lesser extent, its organic analog methylammonium (MeA+). Mutagenesis studies on potential phosphorylation residues have achieved solid recognition that alteration of the phosphorylation status can result in allosteric regulation and impair the functionality of plant AMTs. However, molecular insights to the fine-tuning of a functional ammonium transporter remain less clear. In this report, we demonstrate that the rice root expressed OsAMT1;3 (Oryza sativa ammonium transporter 1;3) functions as a typical high-affinity NH4 + transporter and is weakly permeable to MeA+ using growth assays in NH4 + uptake defective yeast cells and electrophysiological measurements in Xenopus oocytes. Upon screening of six point mutations generated with the transporter, we identified two amino acid residues involved in the functional modulation of OsAMT1;3. The H199E mutation caused loss of transport activity whereas other five mutations retained the functionality of OsAMT1;3. Furthermore, the L56F mutation enabled respectively 5- and 3.5 -fold increased capability for NH4 + and MeA+ uptake with several-fold decreased affinity (K m ) and accelerated V max values. Surprisingly, yeast cells expressing the L56F mutation shown increased Na+ toxicity leading to a speculation that enhanced Na+ permeation occurred with this mutation. The phenomenon was further supported by the observation of significant Na+ uptake current in oocytes. Our results seemingly support a speculation that the L56F mutation of OsAMT1;3 widens the substrate passage tunnel and allows enhanced permeability to NH4 + and larger ions MeA+ and Na+.

      PubDate: 2016-07-16T13:59:19Z
       
  • Impact of cadmium stress on two maize hybrids
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Zuzana Vatehová, Anna Malovíková, Karin Kollárová, Danica Kučerová, Desana Lišková
      Some physiological parameters and composition of the root cell walls of two maize hybrids (monocots), the sensitive Novania and the tolerant Almansa were studied after treatment with cadmium cations. After 10 days of Cd2+ treatment (1 × 10−5 M and 5 × 10−5 M), plant growth inhibition, in the sensitive hybrid in particular, as well as a certain alteration in root structure and pigment content were observed. The Cd2+ accumulation was ten times higher in the roots than in the shoots. Chemical analyses and atomic absorption spectroscopy proved that Cd2+ modified the composition of the root cell walls by a significant increase in the content of alkali-soluble polysaccharide fractions, particularly in the tolerant hybrid. An increase in the content of phenolic compounds, mainly in the tolerant hybrid, and a decrease in protein content were observed in the presence of Cd2+ in the alkali fractions. The results indicate that the changes in the cell wall polysaccharide fractions and their proportion to lignin and cellulose are obviously involved in the tolerance and/or defence against Cd2+ of the maize hybrids studied.
      Graphical abstract image

      PubDate: 2016-07-16T13:59:19Z
       
  • Involvement of vacuolar processing enzyme SlVPE5 in post-transcriptional
           process of invertase in sucrose accumulation in tomato
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Ning Wang, Narendra Duhita, Toru Ariizumi, Hiroshi Ezura
      Enhancing the flavor of fruits plays a fundamental role in improving fruit quality, and volatile compositions as well as acid and sugar accumulation are significant factors that have an impact on the acceptability of sensory responses by human beings. Vacuoles in plants not only function as cell compartments that store amino acids, sugars and other metabolites but also act as lytic organelles where vacuolar proteins are post-translationally processed into mature forms or degraded by the action of vacuolar processing enzyme (VPE). We have previously characterized VPE genes (SlVPE1-5) during fruit development in tomato and discovered that the VPE enzyme activity negatively interfered with sugar accumulation in mature fruits. Comparative proteomic analysis demonstrated that acid invertase was one of the molecular targets of SlVPE5, which is involved in the hydrolysis of sucrose. This study also showed that decreased VPE enzyme activity due to suppression of SlVPE5 by RNAi strategy (RNAi-SlVPE5) accompanied with decreased enzyme activity of acid invertase. Further, we identified the enzyme activity of acid invertase was not well correlated with mRNA levels in the RNAi-SlVPE5 line. These results suggest that SlVPE5 regulates post-transcriptional processing through de novo synthesis of the acid invertase protein to suppress enzyme activity, thereby eventually ensuring sucrose hydrolysis.

      PubDate: 2016-07-16T13:59:19Z
       
  • Magnesium decreases leaf scald symptoms on rice leaves and preserves their
           photosynthetic performance
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): S.D. Tatagiba, F.M. DaMatta, F.A. Rodrigues
      The aim of this study was to investigate the effect of magnesium (Mg) on the photosynthetic gas exchange parameters ([net CO2 assimilation rate (A), stomatal conductance (g s), and internal CO2 concentration (C i)], chlorophyll (Chl) fluorescence a parameters {minimal fluorescence (F 0), maximum fluorescence (F m), maximum quantum yield of photosystem II (F v/F m), photochemical quenching coefficient (q p), yield of photochemistry [Y(II)], yield of regulated energy dissipation [Y(NPQ)] and yield of non-regulated dissipation losses [Y(NO)]} as well as on the concentrations of chloroplastidic pigments in rice plants grown in a nutrient solution containing 0.5 or 1.5 mM of Mg (-Mg or + Mg plants, respectively) and non-inoculated or inoculated with Monographella albescens. A higher Mg supply decreased the leaf scald symptoms in addition to partially preserving the photosynthetic performance of rice leaves challenged with M. albescens. Photosynthetic impairments were associated with photochemical and biochemical dysfunctions at the chloroplast level. The images of Chl a fluorescence evidenced increases in both the Y(II) and q p coupled with decreases in Y(NPQ) associated with a higher Mg supply regardless of inoculation, suggesting increased electron transport rates and lower energy dissipation as heat. Notably, as the leaf scald developed, the use of light energy through photochemical reactions was continuously lost, especially for the inoculated -Mg plants. Interestingly, the lower values for F 0, F m, and F v/F m for -Mg plants were associated with greater photochemical dysfunctions and a progressive loss of photosynthetic pigments during the infection process of M. albescens. The underlying mechanism through which Mg can affect rice resistance against M. albescens remains to be fully elucidated.

      PubDate: 2016-07-12T13:44:21Z
       
  • Sulphur interferes with selenium accumulation in Tartary buckwheat plants
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Aleksandra Golob, Drena Gadžo, Vekoslava Stibilj, Mirha Djikić, Teofil Gavrić, Ivan Kreft, Mateja Germ
      Tartary buckwheat (Fagopyrum tataricum Gaertn.) and common buckwheat (Fagopyrum esculentum Moench.) plants grown in the field were treated foliarly with 126 μM solutions of selenate and/or sulphate in order to study the effect of sulphur (S) on selenium (Se) concentration in plants. In both species, the concentration of Se in all plant parts was similar in control and S treated plants. In Tartary buckwheat the concentration of Se was higher in S and Se treated plants than in plants treated with Se alone. S was shown to enhance Se accumulation in Tartary buckwheat. It was also shown that it is possible to produce grain and herb of Tartary and common buckwheat containing appropriate amounts of Se for food without affecting the yield of the plants.
      Graphical abstract image

      PubDate: 2016-07-12T13:44:21Z
       
  • Molecular characterization of biotic and abiotic stress-responsive MAP
           kinase genes, IbMPK3 and IbMPK6, in sweetpotato
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Ho Soo Kim, Sung-Chul Park, Chang Yoon Ji, Seyeon Park, Jae Cheol Jeong, Haeng-Soon Lee, Sang-Soo Kwak
      Plants are continually exposed to numerous environmental stresses. To decrease damage caused by these potentially detrimental factors, various stress-related signaling cascades are activated in plants. One such stress-responsive signaling pathway, the mitogen-activated protein kinase (MAPK) module, plays a critical role in diverse plant stress responses. Here, we functionally characterized biotic and abiotic stress-responsive MAPK genes, IbMPK3 and IbMPK6, from sweetpotato. IbMPK3/6 contain totally 11 MAPK conserved subdomains and the phosphorylating motif TEY. Bacterially expressed IbMPK3/6 could be autophosphorylated in vitro, and these proteins phosphorylated universal kinase substrate, such as myelin basic protein. IbMPK3/6 transcripts were expressed in leaf, stem, and root of sweetpotato cultivars with storage roots of various colors. IbMPK3 and IbMPK6 were induced by various biotic/abiotic stress treatments. Furthermore, the kinase activity of IbMPK3/6 was induced during early NaCl, SA, H2O2, and ABA treatment. IbMPK3/6 were predominantly localized to the nucleus. To determine the biological functions of IbMPK3/6, we transiently expressed the IbMPK genes in tobacco (Nicotiana benthamiana) leaves, which resulted in enhanced tolerance to bacterial pathogen and increased expression of pathogenesis-related (PR) genes. These data demonstrate that IbMPK3 and IbMPK6 play significant roles in plant responses to environmental stress.

      PubDate: 2016-07-12T13:44:21Z
       
  • Expression of a repressor form of the Arabidopsis thaliana transcription
           factor TCP16 induces the formation of ectopic meristems
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Nora G. Uberti-Manassero, Ezequiel R. Coscueta, Daniel H. Gonzalez
      Plants that express a fusion of the Arabidopsis thaliana class I TCP transcription factor TCP16 to the EAR repressor domain develop several phenotypic alterations, including rounder leaves, short petioles and pedicels, and delayed elongation of sepals, petals and anthers. In addition, these plants develop lobed cotyledons and ectopic meristems. Ectopic meristems are formed on the adaxial side of cotyledon petioles and arise from a cleft that is formed at this site. Analysis of the expression of reporter genes indicated that meristem genes are reactivated at the site of emergence of ectopic meristems, located near the bifurcation of cotyledon veins. The plants also show increased transcript levels of the boundary-specific CUP-SHAPED COTYLEDON (CUC) genes. The results suggest that TCP16 is able to modulate the induction of meristematic programs and the differentiation state of plant cells.

      PubDate: 2016-07-12T13:44:21Z
       
  • The molecular cloning and functional characterization of MdMYC2, a bHLH
           transcription factor in apple
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Jian-Ping An, Hao-Hao Li, Lai-Qing Song, Ling Su, Xin Liu, Chun-Xiang You, Xiao-Fei Wang, Yu-Jin Hao
      The basic helix-loop-helix (bHLH) Leu zipper transcription factor MYC2 is an important regulator in the Jasmonic acid (JA) signaling pathway. In this study, the apple MdMYC2 gene was isolated and cloned on the basis of its homology with Arabidopsis thaliana MYC2. Quantitative real time PCR (qRT-PCR) analysis demonstrated that MdMYC2 transcripts were induced by Methyl Jasmonate (MeJA) treatment and wounding. The MdMYC2 protein interacted with itself and bound the G-Box motif of the AtJAZ3 gene. MdMYC2 interacted with the MdJAZ2 protein, which is a repressor protein in the JA signaling pathway. Furthermore, we obtained transgenic apple calli that either overexpressed or suppressed the MdMYC2 gene. Expression analysis with qRT-PCR demonstrated that the transcript levels of JA-regulated anthocyanin biosynthetic genes, such as MdDFR, MdUF3GT, MdF3H and MdCHS, were markedly up-regulated in the MdMYC2 overexpressing calli and down-regulated in the suppressing calli compared with the WT control. As a result, the overexpressing calli produced more anthocyanin, and the suppressing calli produced less. Finally, the MdMYC2 gene was ectopically expressed in Arabidopsis. Both phenotypic investigation and expression analysis demonstrated that the MdMYC2 transgenic Arabidopsis lines were more sensitive to MeJA than the WT control. Together, these results indicate that the apple MdMYC2 gene plays a vital role in the JA response.

      PubDate: 2016-07-12T13:44:21Z
       
  • Physiological and biochemical characterization of two Amaranthus species
           under Cr(VI) stress differing in Cr(VI) tolerance
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Gausiya Bashri, Parul Parihar, Rachana Singh, Samiksha Singh, Vijay Pratap Singh, Sheo Mohan Prasad
      The present study was undertaken to evaluate Cr(VI) toxicity tolerance in two Amaranthus species viz. Amaranthus viridis and Amaranthus cruentus exposed to hexavalent chromium [Cr(VI)] stress. To ascertain this, both Amaranthus species were grown under various concentrations (0, 10 and 50 μM) of Cr(VI) in the hydroponic system. After 7 days of Cr(VI) treatment, various traits such as growth, Cr accumulation, photochemistry of photosystem II (PS II) (JIP-test), oxidative stress and antioxidant defense system were analyzed. Cr(VI) treatments caused inhibition in growth and PS II photochemistry, which was accompanied with increased accumulation of Cr that results into enhanced generation of reactive oxygen species (ROS): O2 − and H2O2, which subsequently induced the peroxidation of lipids and leakage of electrolyte in both the Amaranthus species. Cr(VI) accumulation, lipid peroxidation and electrolyte leakage were more pronounced in A. viridis than in A. cruentus. On the other hand, A. cruentus seedlings showed higher activities of enzymatic antioxidants: SOD, POD, CAT and GST, and non-enzymatic antioxidants: cysteine and non-protein thiols (NP-SH) levels than A. viridis. The overall results suggest that A. cruentus is more tolerant than A. viridis due to its higher antioxidant defense system that protected seedlings under Cr(VI) stress.

      PubDate: 2016-07-07T12:49:49Z
       
  • Genome-wide characterization of pectin methyl esterase genes reveals
           members differentially expressed in tolerant and susceptible wheats in
           response to Fusarium graminearum
    • Abstract: Publication date: November 2016
      Source:Plant Physiology and Biochemistry, Volume 108
      Author(s): Alessandra Zega, Renato D’Ovidio
      Pectin methyl esterase (PME) genes code for enzymes that are involved in structural modifications of the plant cell wall during plant growth and development. They are also involved in plant-pathogen interaction. PME genes belong to a multigene family and in this study we report the first comprehensive analysis of the PME gene family in bread wheat (Triticum aestivum L.). Like in other species, the members of the TaPME family are dispersed throughout the genome and their encoded products retain the typical structural features of PMEs. qRT-PCR analysis showed variation in the expression pattern of TaPME genes in different tissues and revealed that these genes are mainly expressed in flowering spikes. In our attempt to identify putative TaPME genes involved in wheat defense, we revealed a strong variation in the expression of the TaPME following Fusarium graminearum infection, the causal agent of Fusarium head blight (FHB). Particularly interesting was the finding that the expression profile of some PME genes was markedly different between the FHB-resistant wheat cultivar Sumai3 and the FHB-susceptible cultivar Bobwhite, suggesting a possible involvement of these PME genes in FHB resistance. Moreover, the expression analysis of the TaPME genes during F. graminearum progression within the spike revealed those genes that responded more promptly to pathogen invasion.

      PubDate: 2016-07-07T12:49:49Z
       
 
 
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