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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  [2800 journals]
  • Different responses of low grain-Cd-accumulating and high
           grain-Cd-accumulating rice cultivars to Cd stress
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Feijuan Wang, Min Wang, Zhouping Liu, Yan Shi, Tiqian Han, Yaoyao Ye, Ning Gong, Junwei Sun, Cheng Zhu
      Cadmium (Cd) is a major heavy metal pollutant which is highly toxic to plants and animals. The accumulation of Cd in rice grains is a major agricultural problem in regions with Cd pollution. A hydroponics experiment using low grain-Cd-accumulating rice (xiushui 11) and high grain-Cd-accumulating rice (xiushui 110) was carried out to characterize the different responses of rice cultivars to Cd stress. We found that xiushui 11 was more tolerant to Cd than xiushui 110, and xiushui 11 suffered less oxidative damage. Cell walls played an important role in limiting the amount of Cd that entered the protoplast, especially in xiushui 11. Cd stored in organelles as soluble fractions, leading to greater physiological stress of Cd detoxification. We found that Cd can disturb the ion homeostasis in rice roots because Cd2+ and Ca2+ may have a similar uptake route. Xiushui 11 had a faster root-to-shoot transport of Cd, and the expression level of OsPCR1 gene which was predicted related with Cd accumulation in rice was consist with the Cd transport of root-to-shoot in rice and maintain the greater Cd tolerance of xiushui 11. These results suggest there are different Cd detoxification and accumulation mechanisms in rice cultivars.
      Graphical abstract image

      PubDate: 2015-08-29T16:22:52Z
       
  • Analysis of expression and inhibitory activity of a TrcC-6 phytocystatin
           present in developing and germinating seeds of triticale
           (×Triticosecale Wittm.)
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Joanna Simińska, Sławomir Orzechowski, Wiesław Bielawski
      Storage proteins of cereal seeds are processed during accumulation and degraded during germination primarily by cysteine proteinases. One of the mechanisms controlling the activity of these enzymes is the synthesis of specific inhibitors named phytocystatins. Here we present the complete gene sequence of a triticale ( × Triticosecale Wittm.) phytocystatin, TrcC-6, which encodes a 152-amino acid protein with a putative 25-amino acid signal peptide. This protein has a calculated molecular mass of 16.2 kDa, and was assigned to phylogenetic group B of phytocystatins. Because TrcC-6 transcripts are present in triticale seeds, we hypothesized that this phytocystatin regulates storage protein accumulation and degradation. Therefore, changes in gene expression during the entire period of seed development and germination were examined. TrcC-6 transcripts and TrcC-6 protein levels increased during the maturation of seeds and remained high during the first hours of germination. This enabled us to conclude that TrcC-6 likely regulates seed germination by the regulation of storage protein hydrolysis. For the analysis of TrcC-6 inhibitory activity, recombinant protein was expressed in Escherichia coli BL21 (DE3) and purified. Recombinant TrcC-6 proved to be a potent inhibitor of cysteine proteinases. It inhibited the in vitro activity of papain (EC 3.4.22.2) and ficin (EC 3.4.22.3). Furthermore, native PAGE analysis revealed that recombinant TrcC-6 inhibits the activity of endogenous cysteine proteinases present in germinating seeds of triticale. Based on these results, TrcC-6 is likely one of the important factors that regulate cysteine proteinase activity during the accumulation and mobilization of storage proteins.


      PubDate: 2015-08-25T16:03:43Z
       
  • Systemic and local regulation of phosphate and nitrogen transporter genes
           by arbuscular mycorrhizal fungi in roots of winter wheat (Triticum
           aestivum L.)
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Jianfeng Duan, Hui Tian, Rhae A. Drijber, Yajun Gao
      Previous studies have reported that the expression of phosphate (Pi) or nitrogen (N) transporter genes in roots of plants could be regulated by arbuscular mycorrhizal (AM) fungi, but little is known whether the regulation is systemic or not. The present study investigated the systemic and local regulation of multiple phosphate and nitrogen transporter genes by four AM fungal species belonging to four genera in the roots of winter wheat. A split-root culture system with AM inoculated (MR) and non-inoculated root compartments (NR) was used to investigate the systemic or local responses of phosphate and nitrogen transporter genes to colonization by four AM fungi in the roots of wheat. The expression of four Pi transporter, five nitrate transporter, and three ammonium transporter genes was quantified using real-time PCR. Of the four AM fungi tested, all locally increased expression of the AM-inducible Pi transporter genes, and most locally decreased expression of a Pi-starvation inducible Pi transporter gene. The addition of N in soil increased the expression of either Pi starvation inducible Pi transporters or AM inducible Pi transporters. Inoculation with AM fungi either had no effect, or could locally or systemically down-regulate expression of nitrogen transporter genes depending on gene type and AM fungal species.


      PubDate: 2015-08-25T16:03:43Z
       
  • Suppressed expression of choline monooxygenase in sugar beet on the
           accumulation of glycine betaine
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Nana Yamada, Hiroyuki Takahashi, Kunihide Kitou, Kosuke Sahashi, Hideto Tamagake, Yoshito Tanaka, Teruhiro Takabe
      Glycine betaine (GB) is an important osmoprotectant and synthesized by two-step oxidation of choline. Choline monooxygenase (CMO) catalyzes the first step of the pathway and is believed to be a rate limiting step for GB synthesis. Recent studies have shown the importance of choline-precursor supply for GB synthesis. In order to investigate the role of CMO for GB accumulation in sugar beet (Beta vulgaris), transgenic plants carrying the antisense BvCMO gene were developed. The antisense BvCMO plants showed the decreased activity of GB synthesis from choline compared to wild-type (WT) plants which is well related to the suppressed level of BvCMO protein. However, GB contents were similar between transgenic and WT plants with the exception of young leaves and storage roots. Transgenic plants showed enhanced susceptibility to salt stress than WT plants. These results suggest the importance of choline-precursor-supply for GB accumulation, and young leaves and storage root are sensitive sites for GB accumulation.


      PubDate: 2015-08-25T16:03:43Z
       
  • Decreased seed oil production in FUSCA3 Brassica napus mutant plants
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Nosheen Elahi, Robert W. Duncan, Claudio Stasolla
      Canola (Brassica napus L.) oil is extensively utilized for human consumption and industrial applications. Among the genes regulating seed development and participating in oil accumulation is FUSCA3 (FUS3), a member of the plant-specific B3-domain family of transcription factors. To evaluate the role of this gene during seed storage deposition, three BnFUSCA3 (BnFUS3) TILLING mutants were generated. Mutations occurring downstream of the B3 domain reduced silique number and repressed seed oil level resulting in increased protein content in developing seeds. BnFUS3 mutant seeds also had increased levels of linoleic acid, possibly due to the reduced expression of ω-3 FA DESATURASE (FAD3). These observed phenotypic alterations were accompanied by the decreased expression of genes encoding transcription factors stimulating fatty acid (FA) synthesis: LEAFY COTYLEDON1 and 2 (LEC1 and 2) ABSCISIC ACID-INSENSITIVE 3 (BnABI3) and WRINKLED1 (WRI1). Additionally, expression of genes encoding enzymes involved in sucrose metabolism, glycolysis, and FA modifications were down-regulated in developing seeds of the mutant plants. Collectively, these transcriptional changes support altered sucrose metabolism and reduced glycolytic activity, diminishing the carbon pool available for the synthesis of FA and ultimately seed oil production. Based on these observations, it is suggested that targeted manipulations of BnFUS3 can be used as a tool to influence oil accumulation in the economically important species B. napus.


      PubDate: 2015-08-25T16:03:43Z
       
  • Silicon nanoparticles (SiNp) alleviate chromium (VI) phytotoxicity in
           Pisum sativum (L.) seedlings
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Durgesh Kumar Tripathi, Vijay Pratap Singh, Sheo Mohan Prasad, Devendra Kumar Chauhan, Nawal Kishore Dubey
      The present study was aimed to investigate the effect of silicon nanoparticles (SiNp) against Cr (VI) phytotoxicity in pea seedlings. Results show that Cr(VI, 100 μM) significantly (P < 0.05) declined growth of pea which was accompanied by the enhanced level of Cr. Additionally, photosynthetic pigments and chlorophyll fluorescence parameters like Fv/Fm, Fv/F0 and qP were decreased while NPQ significantly (P < 0.05) increased under Cr(VI) treatment. Superoxide radical, hydrogen peroxide and malondialdehyde (MDA-lipid peroxidation) contents were enhanced by Cr(VI). Activities of antioxidant enzymes like superoxide dismutase and ascorbate peroxidase were increased by Cr (VI) while activities of catalase, glutathione reductase and dehydroascorbate reductase were inhibited significantly (P < 0.05). Micro and macronutrients also show decreasing trends (except S) under Cr(VI) treatment. However, addition of SiNp together with Cr(VI) protects pea seedlings against Cr(VI) phytotoxicity hence improved growth was noticed. In conclusion, the results of this study show that Cr(VI) causes negative impact on pea seedlings, however; SiNp protects pea seedlings against Cr(VI) phytotoxicity by reducing Cr accumulation and oxidative stress, and up-regulating antioxidant defense system and nutrient elements.


      PubDate: 2015-08-25T16:03:43Z
       
  • Roles of DgD14 in regulation of shoot branching in chrysanthemum
           (Dendranthema grandiflorum ‘Jinba’)
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Chao Wen, Lin Xi, Bin Gao, Keyong Wang, Suhui Lv, Yaping Kou, Nan Ma, Liangjun Zhao
      Shoot branching plays an important role in determining plant architecture. Strigolactones (SLs) negatively regulate shoot branching, and can respond to conditions of low or absent phosphate or nitrogen. The D14 gene is a probable candidate as an SL receptor in rice, petunia, and Arabidopsis. To investigate the roles of D14 in shoot branching of chrysanthemum, we isolated the D14 homolog DgD14. Functional analysis showed that DgD14 was a nuclear-localized protein, and restored the phenotype of Arabidopsis d14-1. Exogenous SL (GR24) could down-regulate DgD14 expression, but this effect could be overridden by apical auxin application. Decapitation could down-regulate DgD14 expression, but this effect could be restored by exogenous auxin. In addition, DgD14 transcripts produced rapid responses in shoot and root under conditions of phosphate absence, but only a mild variation in bud and stem with low nitrogen treatment. Indistinct reductions of P levels in shoot were observed in plants grown under low nitrogen conditions. The absence of phosphate and low levels of nitrogen negatively affected plant growth. These results demonstrate that P levels in shoot had a close relationship with phosphate, whereas nitrogen did not directly regulate DgD14 expression in shoot. Taken together, these results demonstrated that DgD14 was the functional strigolactone signaling component in chrysanthemum.


      PubDate: 2015-08-25T16:03:43Z
       
  • MhNCED3 in Malus hupehensis Rehd. induces NO generation under osmotic
           stress by regulating ABA accumulation
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Wei-wei Zhang, Hong-qiang Yang, Shu-zhen You, Kun Ran
      Abscisic acid (ABA) biosynthesis has been widely characterized in plants, whereas the effects of ABA biosynthesis on nitric oxide (NO) generation in osmotic stress are less well understood. In this study, Malus hupehensis Rehd. 9-cis-epoxycarotenoid dioxygenase gene (MhNCED3) which is the key gene in ABA biosynthesis was transformed into wild type (WT) and 129B08/nced3 mutant (AtNCED3 deficient), respectively, and two transgenic Arabidopsis lines were obtained. The transgenic Arabidopsis lines displayed higher endogenous ABA content, NO generation rate, AtNIA1 transcript level and nitrate reductase (NR) activity than WT and 129B08/nced3 mutant. Ectopic expression of MhNCED3 reduced the electrolyte leakage and relieved Arabidopsis damage caused by 20% PEG on the growth and development. The ABA content, NO generation rate, AtNIA1 expression and NR activity increased after 20% PEG treatment, importantly, their increases amplitude relative to that in control were higher in two transgenic lines. Additionally, during the treatment for the four genotype Arabidopsis, the time of ABA contents reaching the highest peak was earlier than the time of NO generation, AtNIA1 expression and NR activity reaching their highest peak. These results show that NCED gene indirectly induced endogenous NO generation in osmotic-stressed Arabidopsis partially contributing to the up-regulation of AtNIA1 expression and NR activity.


      PubDate: 2015-08-25T16:03:43Z
       
  • POLYAMINE OXIDASE2 of Arabidopsis contributes to ABA mediated plant
           developmental processes
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Rinukshi Wimalasekera, Frank Schaarschmidt, Riccardo Angelini, Alessandra Cona, Parasklevi Tavladoraki, Günther F.E. Scherer
      Polyamines (PA) are catabolised by two groups of amine oxidases, the copper-binding amine oxidases (CuAOs) and the FAD-binding polyamine oxidases (PAOs). Previously, we have shown that CuAO1 is involved in ABA associated growth responses and ABA- and PA-mediated rapid nitric oxide (NO) production. Here we report the differential regulation of expression of POLYAMINE OXIDASE2 of Arabidopsis (AtPAO2) in interaction with ABA, nitrate and ammonium. Without ABA treatment germination, cotyledon growth and fresh weight of pao2 knockdown mutants as well as PAO2OX over-expressor plants were comparable to those of the wild type (WT) plants irrespective of the N source. In the presence of ABA, in pao2 mutants cotyledon growth and fresh weights were more sensitive to inhibition by ABA while PAO2OX over-expressor plants showed a rather similar response to WT. When NO3 − was the only N source primary root lengths and lateral root numbers were lower in pao2 mutants both without and with exogenous ABA. PAO2OX showed enhanced primary and lateral root growth in media with NO3 − or NH4 +. Vigorous root growth of PAO2OX and the hypersensitivity of pao2 mutants to ABA suggest a positive function of AtPAO2 in root growth. ABA-induced NO production in pao2 mutants was lower indicating a potential contributory function of AtPAO2 in NO-mediated effects on root growth.


      PubDate: 2015-08-25T16:03:43Z
       
  • Editorial Board
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95




      PubDate: 2015-08-20T15:40:11Z
       
  • Physiological responses in roots of the grapevine rootstock 140 Ruggeri
           subjected to Fe deficiency and Fe-heme nutrition
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Sandra López-Rayo, Michele Di Foggia, Erica Rodrigues Moreira, Silvia Donnini, Giuseppe Bombai, Gianfranco Filippini, Annamaria Pisi, Adamo D. Rombolà
      Iron (Fe)-heme containing fertilizers can effectively prevent Fe deficiency. This paper aims to investigate root physiological responses after a short period of Fe-heme nutrition and Fe deficiency under two pH conditions (with or without HEPES) in the Fe chlorosis-tolerant grapevine rootstock 140 Ruggeri. Organic acids in root exudates, Fe reduction capacity, both roots and root exudates contributions, together with other physiological parameters associated to plant Fe status were evaluated in plants grown in hydroponics. Analyses of root tips by SEM, and Raman and IR spectra of the precipitates of Fe-heme fertilizers were performed. The physiological responses adopted by the tolerant 140 Ruggeri to the application of Fe-heme indicated an increased Fe reduction capacity of the roots. This is the first report showing oxalic, tartaric, malic and ascorbic as major organic acids in Vitis spp. root exudates. Plants reacted to Fe deficiency condition exuding a higher amount of ascorbic acid in the rhizosphere. The presence of HEPES in the medium favoured the malic acid exudation. The lowest concentration of oxalic acid was found in exudates of plants subjected to Fe-heme and could be associated to a higher accumulation in their root tips visualized by SEM analysis.


      PubDate: 2015-08-16T09:33:12Z
       
  • The effect of choline-stabilized orthosilicic acid on microelements and
           silicon concentration, photosynthesis activity and yield of tomato grown
           under Mn stress
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Tomasz Kleiber, Mario Calomme, Klaudia Borowiak
      The aim of experiments was to assess the efficiency of choline-stabilized orthosilicic acid (ch-OSA; complex of orthosilicic acid with choline and a bioavailable source of silicon) application under increasing manganese (Mn) stress on the micronutritional composition and yielding of tomato (Solanum lycopersicum L. cvs. ‘Alboney F1’ and ‘Emotion F1’). Plants were grown in rockwool with the application of a nutrient solution varied the Mn concentrations (in mg dm−3): 9.6 and 19.2 which cause strong oxidative stress of plants comparing with optimal concentration of that microelement in nutrient solution. The effect of ch-OSA application (at Si concentration of 0.3 mg dm−3 nutrient solution) was investigated at both Mn-levels. Increasing Mn stress modified the concentration of microelements and silicon (Si) in tomato leaves. Application of ch-OSA also influenced the concentration of nutrients, but the determined changes were generally multidirectional and varied depending on Mn-level and cultivar. Under the increasing Mn stress a significant downward trend was observed for the mean concentration of Fe (in both cultivars) in fruits – but changes of Mn, Zn and Cu were varied depend on cultivar. In the case of cv. ‘Alboney F1’ ch-OSA application caused an increase the mean concentrations of Fe, Zn and Cu, while in the case of cv. ‘Emotion F1’ the reduction of mean concentrations of Zn and Cu was recorded. Ch-OSA treatment did not influence on the Mn concentrations in fruits. A beneficial role of ch-OSA was also found in photosynthesis activity. This was especially valid for lower levels of Mn. Application of ch-OSA improved significantly the marketable yield of tomato under stress by a low Mn level.


      PubDate: 2015-08-16T09:33:12Z
       
  • Plastoquinone redox state modifies plant response to pathogen
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Michał Nosek, Andrzej Kornaś, Elżbieta Kuźniak, Zbigniew Miszalski
      The role of PQ (plastoquinione) redox state in establishment of response to pathogen infection (Botrytis cinerea) was tested along the regulation of main antioxidative enzymes (superoxide dismutase – SOD, catalase – CAT) and photochemistry of PSII (photosystem II) in Mesembryanthemum crystallinum plants performing C3 and CAM (Crassulacean acid metabolism) carbon metabolism. The redox state of PQ was modified by two inhibitors of photosynthetic electron transport resulting in a more oxidised (3-(3,4-dichlorophenyl)-1,1-dimethylurea; DCMU) or reduced (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone; DBMIB) PQ redox state simulating darkness and high light conditions, respectively. Irrespective of the type of treatment (mock inoculation or pathogen inoculation) SOD activity depended on the PQ pool. Our results suggest that regarding changes in infection-induced CAT activity, plants developed response that is vital for hypersensitive-like (HR-like) response establishment only when PQ pool generated signal was similar to that in light presence (DBMIB pre-treatment). When PQ pool generated signal was similar to darkness, CAT activity response remained stress-independent, similarly to SOD. Fluorescence parameters of PSII, Qp (photochemical quenching coefficient) and NPQ (non-photochemical quenching) were affected only in the tissues treated with DCMU in stress-independent manner. We suggest that in case of abiotic and biotic stresses signals emerging from PQ pool indirectly orchestrate plant response and carbon metabolism affects this regulatory pathway.


      PubDate: 2015-08-12T09:30:50Z
       
  • Comprehensive analysis and expression profile of the homeodomain leucine
           zipper IV transcription factor family in tomato
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Yanna Gao, Shenghua Gao, Cheng Xiong, Gang Yu, Jiang Chang, Zhibiao Ye, Changxian Yang
      Homeodomain leucine zipper IV (HD-ZIP IV) proteins are plant-specific transcription factors that play important roles in development of epidermal cell layers and cuticle formation. The functions of two HD-ZIP IV family genes, CD2 and Wo, have been well characterized in tomato (Solanum lycopersicum). CD2 and Wo are involved in cuticle biosynthesis and trichome formation, respectively. In this study, we identified 13 novel tomato HD-ZIP IV (SlHDZIV) genes. We analyzed the structures, chromosome locations, phylogeny, protein motifs, and expression profiles of these SlHDZIV genes. Gene structure analysis revealed that a module of 11 exons and 10 introns existed in the SlHDZIV genes. These genes were asymmetrically distributed on chromosomes, except on chromosome 4 and 5. Segmental duplication possibly contributed to the expansion of tomato HD-ZIP IV genes. The expression profiles of these genes revealed their broad expression pattern and high expression in young leaves and flowers. Each gene responded to more than one of different phytohormones [abscisic acid, ethephon, 4-(indolyl)-butyric acid, jasmonic acid, salicylic acid, gibberellic acid, and 6-benzylaminopurine] and four abiotic stress treatments (cold, heat, salt, and drought). This study provided significant insights into the diverse roles of SlHDZIV genes in tomato growth and development.


      PubDate: 2015-08-12T09:30:50Z
       
  • De novo assembly and characterization of germinating lettuce seed
           transcriptome using Illumina paired-end sequencing
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Shu-Jun Liu, Shun-Hua Song, Wei-Qing Wang, Song-Quan Song
      At supraoptimal temperature, germination of lettuce (Lactuca sativa L.) seeds exhibits a typical germination thermoinhibition, which can be alleviated by sodium nitroprusside (SNP) in a nitric oxide-dependent manner. However, the molecular mechanism of seed germination thermoinhibition and its alleviation by SNP are poorly understood. In the present study, the lettuce seeds imbibed at optimal temperature in water or at supraoptimal temperature with or without 100 μM SNP for different periods of time were used as experimental materials, the total RNA was extracted and sequenced, we gained 147,271,347 raw reads using Illumina paired-end sequencing technique and assembled the transcriptome of germinating lettuce seeds. A total of 51,792 unigenes with a mean length of 849 nucleotides were obtained. Of these unigenes, a total of 29,542 unigenes were annotated by sequence similarity searching in four databases, NCBI non-redundant protein database, SwissProt protein database, euKaryotic Ortholog Groups database, and NCBI nucleotide database. Among the annotated unigenes, 22,276 unigenes were assigned to Gene Ontology database. When all the annotated unigenes were searched against the Kyoto Encyclopedia of Genes and Genomes Pathway database, a total of 8,810 unigenes were mapped to 5 main categories including 260 pathways. We first obtained a lot of unigenes encoding proteins involved in abscisic acid (ABA) signaling in lettuce, including 11 ABA receptors, 94 protein phosphatase 2Cs and 16 sucrose non-fermenting 1-related protein kinases. These results will help us to better understand the molecular mechanism of seed germination, thermoinhibition of seed germination and its alleviation by SNP.


      PubDate: 2015-08-12T09:30:50Z
       
  • Stress-responsive expression patterns and functional characterization of
           cold shock domain proteins in cabbage (Brassica rapa) under abiotic stress
           conditions
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Min Ji Choi, Ye Rin Park, Su Jung Park, Hunseung Kang
      Although the functional roles of cold shock domain proteins (CSDPs) have been demonstrated during the growth, development, and stress adaptation of Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa), and wheat (Triticum aestivum), the functions of CSDPs in other plants species, including cabbage (Brassica rapa), are largely unknown. To gain insight into the roles of CSDPs in cabbage under stress conditions, the genes encoding CSDPs in cabbage were isolated, and the functional roles of CSDPs in response to environmental stresses were analyzed. Real-time RT-PCR analysis revealed that the levels of BrCSDP transcripts increased during cold, salt, or drought stress, as well as upon ABA treatment. Among the five BrCSDP genes found in the cabbage genome, one CSDP (BRU12051), named BrCSDP3, was unique in that it is localized to the chloroplast as well as to the nucleus. Ectopic expression of BrCSDP3 in Arabidopsis resulted in accelerated seed germination and better seedling growth compared to the wild-type plants under high salt or dehydration stress conditions, and in response to ABA treatment. BrCSDP3 did not affect the splicing of intron-containing genes and processing of rRNAs in the chloroplast. BrCSDP3 had the ability to complement RNA chaperone-deficient Escherichia coli mutant cells under low temperatures as well as DNA- and RNA-melting abilities, suggesting that it possesses RNA chaperone activity. Taken together, these results suggest that BrCSDP3, harboring RNA chaperone activity, plays a role as a positive regulator in seed germination and seedling growth under stress conditions.


      PubDate: 2015-08-12T09:30:50Z
       
  • Nitric oxide modulates Lycopersicon esculentum C-repeat binding factor 1
           (LeCBF1) transcriptionally as well as post-translationally by
           nitrosylation
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Prakriti Kashyap, Ankita Sehrawat, Renu Deswal
      Nitric oxide (NO) production increases in the cold stress. This cold enhanced NO manifests its effect either by regulating the gene expression or by modulating proteins by NO based post-translational modifications (PTMs) including S-nitrosylation. CBF (C-repeat binding factor) dependent cold stress signaling is most studied cold stress-signaling pathway in plants. SNP (sodium nitroprusside, a NO donor) treatment to tomato seedlings showed four fold induction of LeCBF1 (a cold inducible CBF) transcript in cold stress. S-nitrosylation as PTM of CBF has not been analyzed till date. In silico analysis using GPS-SNO 1.0 software predicted Cys 68 as the probable site for nitrosylation in LeCBF1. The 3D structure and motif prediction showed it to be present in the beta hairpin loop and hence available for S-nitrosylation. LeCBF1 was cloned and expressed in Escherichia coli. LeCBF1 accumulated in the inclusion bodies, which were solubilized under denaturing conditions and purified after on column refolding by Ni-NTA His tag affinity chromatography. Purified LeCBF1 resolved as a 34 kDa spot with a slightly basic pI (8.3) on a 2-D gel. MALDI-TOF mass spectrometry identified it as LeCBF1 and western blotting using anti-LeCBF1 antibodies confirmed its purification. Biotin switch assay and neutravidin affinity chromatography showed LeCBF1 to be S-nitrosylated in presence of GSNO (NO donor) as well as endogenously (without donor) in cold stress treated tomato seedlings. Dual regulation of LeCBF1 by NO at both transcriptional as well as post-translational level (by S-nitrosylation) is shown for the first time.


      PubDate: 2015-08-08T09:21:04Z
       
  • Metabolic cross-talk between pathways of terpenoid backbone biosynthesis
           in spike lavender
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Isabel Mendoza-Poudereux, Erika Kutzner, Claudia Huber, Juan Segura, Wolfgang Eisenreich, Isabel Arrillaga
      The metabolic cross-talk between the mevalonate (MVA) and the methylerythritol phosphate (MEP) pathways in developing spike lavender (Lavandula latifolia Med) was analyzed using specific inhibitors and on the basis of 13C-labeling experiments. The presence of mevinolin (MEV), an inhibitor of the MVA pathway, at concentrations higher than 0.5 μM significantly reduced plant development, but not the synthesis of chlorophylls and carotenoids. On the other hand, fosmidomycin (FSM), an inhibitor of the MEP pathway, at concentrations higher than 20 μM blocked the synthesis of chlorophyll, carotenoids and essential oils, and significantly reduced stem development. Notably, 1.2 mM MVA could recover the phenotype of MEV-treated plants, including the normal growth and development of roots, and could partially restore the biosynthesis of photosynthetic pigments and, to a lesser extent, of the essential oils in plantlets treated with FSM. Spike lavender shoot apices were also used in 13C-labeling experiments, where the plantlets were grown in the presence of [U–13C6]glucose. GC-MS-analysis of 1,8-cineole and camphor indicated that the C5-precursors, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) of both monoterpenes are predominantly biosynthesized via the methylerythritol phosphate (MEP) pathway. However, on the basis of the isotopologue profiles, a minor contribution of the MVA pathway was evident that was increased in transgenic spike lavender plants overexpressing the 3-hydroxy-3-methylglutaryl CoA reductase (HMGR), the first enzyme of the MVA pathway. Together, these findings provide evidence for a transport of MVA-derived precursors from the cytosol to the plastids in leaves of spike lavender.


      PubDate: 2015-08-08T09:21:04Z
       
  • Expression profiles of genes related to carbohydrate metabolism provide
           new insights into carbohydrate accumulation in seeds and seedlings of
           Ricinus communis in response to temperature
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Paulo R. Ribeiro, Wilco Ligterink, Henk W.M. Hilhorst
      Ricinus communis possesses a specific metabolic signature to adjust growth and developmental processes in response to temperature: carbohydrates are accumulated at low temperatures, whereas amino acids are accumulated at elevated temperatures. Our objective was to assess tissue-specific changes in transcript levels of genes related with carbohydrate biosynthesis and catabolism in response to temperature. For that, we measured transcript levels of genes encoding enzymes involved in starch biosynthesis, starch catabolism, and gluconeogenesis in R. communis leaves, roots, and seeds grown at 20 °C and 35 °C. Transcript levels of genes involved in starch catabolism were higher in leaves grown at 20 °C than at 35 °C, but up-regulation of genes involved in starch biosynthesis seems to compensate for this and, therefore, are the likely explanation for higher levels of starch in leaves grown at 20 °C. Higher levels of soluble carbohydrates in leaves grown at 20 °C may be caused by a coordinated increase in transcript level of genes associated with starch catabolism and gluconeogenesis pathways. In roots, transcript levels of genes associated with starch catabolism and gluconeogenesis seem to be enhanced at elevated temperatures. Higher levels of starch in seeds germinated at low temperatures is associated with higher transcript levels of genes involved in starch biosynthesis. Similarly, higher transcript levels of RcPEPCK and RcFBPase are most likely causal for fructose and glucose accumulation in seeds germinated at 20 °C. This study provides important insights in the understanding of the plasticity of R. communis in response to temperature that may apply to other species as well.
      Graphical abstract image

      PubDate: 2015-08-08T09:21:04Z
       
  • Ultraviolet-B radiation applied to detached peach fruit: A study of free
           radical generation by EPR spin trapping
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): C. Sgherri, C. Scattino, C. Pinzino, P. Tonutti, A.M. Ranieri
      In peaches, phenolic compounds are the major sources of antioxidants, and cyanidin-3-O-glucoside is the main anthocyanin present, above all in the skin. Anthocyanin content has been shown to increase after UV-B irradiation, which may be very harmful for all biological organisms due to the induction of the generation of reactive oxygen species (ROS). Peach fruits (cv. ‘Suncrest’) were exposed during post-harvest to supplemental ultraviolet-B radiation. A spin-trapping technique was used to monitor the generation of free radicals under UV-B, and 5-(diethoxy-phosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) was used as the spin trap. The flesh of peaches was essentially unaffected by the treatment, whereas the skin was responsive at the end of the treatment, accumulating ascorbate, flavonoids, cyanidin-3-O-glucoside, and showing a higher antioxidant activity. The levels of stable free radicals were also lower at the end of treatment. Carbon-centred radicals contributed the most to the total amounts of free radicals, whereas hydroxyl radicals and oxygen-centred free radicals contributed minimally. The carbon-centred free radical identified was the same as the one obtained after irradiation of authentic cyanidin-3-O-glucoside. During UV-B treatment cyanidin-3-O-glucoside increased and was capable of radicalization protecting the other organic molecules of the cell from oxidation. ROS, among which hydroxyl radicals, were thus maintained to minimal levels. This ability of cyanidin-3-O-glucoside displayed the mechanism underlined the tolerance to UV-B irradiation indicating that shelf life can be prolonged by the presence of anthocyanins. Thus, UV-B technique results a good approach to induce antioxidant production in peach fruits increasing their nutraceutical properties.
      Graphical abstract image

      PubDate: 2015-08-08T09:21:04Z
       
  • Aquaporins in Coffea arabica L.: Identification, expression, and impacts
           on plant water relations and hydraulics
    • Abstract: Publication date: October 2015
      Source:Plant Physiology and Biochemistry, Volume 95
      Author(s): Matilda Miniussi, Lorenzo Del Terra, Tadeja Savi, Alberto Pallavicini, Andrea Nardini
      Plant aquaporins (AQPs) are involved in the transport of water and other small solutes across cell membranes, and thus play major roles in the regulation of plant water balance, as well as in growth regulation and response to abiotic stress factors. Limited information is currently available about the presence and role of AQPs in Coffea arabica L., despite the economic importance of the species and its vulnerability to drought stress. We identified candidate AQP genes by screening a proprietary C. arabica transcriptome database, resulting in the identification of nine putative aquaporins. A phylogenetic analysis based on previously characterized AQPs from Arabidopsis thaliana and Solanum tuberosum allowed to assign the putative coffee AQP sequences to the Tonoplast (TIP) and Plasma membrane (PIP) subfamilies. The possible functional role of coffee AQPs was explored by measuring hydraulic conductance and aquaporin gene expression on leaf and root tissues of two-year-old plants (C. arabica cv. Pacamara) subjected to different experimental conditions. In a first experiment, we tested plants for root and leaf hydraulic conductance both before dawn and at mid-day, to check the eventual impact of light on AQP activity and plant hydraulics. In a second experiment, we measured plant hydraulic responses to different water stress levels as eventually affected by changes in AQPs expression levels. Our results shed light on the possible roles of AQPs in the regulation of C. arabica hydraulics and water balance, opening promising research lines to improve the sustainability of coffee cultivation under global climate change scenarios.


      PubDate: 2015-08-04T03:52:02Z
       
  • Additional diterpenes from Physcomitrella patens synthesized by copalyl
           diphosphate/kaurene synthase (PpCPS/KS)
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Xin Zhan, Søren Spanner Bach, Nikolaj Lervad Hansen, Christina Lunde, Henrik Toft Simonsen
      The bifunctional diterpene synthase, copalyl diphosphate/kaurene synthase from the moss Physcomitrella patens (PpCPS/KS), catalyses the formation of at least four diterpenes, including ent-beyerene, ent-sandaracopimaradiene, ent-kaur-16-ene, and 16-hydroxy-ent-kaurene. The enzymatic activity has been confirmed through generation of a targeted PpCPS/KS knock-out mutant in P. patens via homologous recombination, through transient expression of PpCPS/KS in Nicotiana benthamiana, and expression of PpCPS/KS in E. coli. GC-MS analysis of the knock-out mutant shows that it lacks the diterpenoids, supporting that all are products of PpCPS/KS as observed in N. benthamiana and E. coli. These results provide additional knowledge of the mechanism of this bifunctional diterpene synthase, and are in line with proposed reaction mechanisms in kaurene biosynthesis.


      PubDate: 2015-08-04T03:52:02Z
       
  • Is salt stress tolerance in Casuarina glauca Sieb. ex Spreng. associated
           with its nitrogen-fixing root-nodule symbiosis' An analysis at the
           photosynthetic level
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Paula Batista-Santos, Nuno Duro, Ana P. Rodrigues, José N. Semedo, Paula Alves, Mário da Costa, Inês Graça, Isabel P. Pais, Paula Scotti-Campos, Fernando C. Lidon, António E. Leitão, Katharina Pawlowski, Ana I. Ribeiro-Barros, José C. Ramalho
      Casuarina glauca is an actinorhizal tree which establishes root-nodule symbiosis with N2-fixing Frankia bacteria. This plant is commonly found in saline zones and is widely used to remediate marginal soils and prevent desertification. The nature of its ability to survive in extreme environments and the extent of Frankia contribution to stress tolerance remain unknown. Thus, we evaluated the ability of C. glauca to cope with salt stress and the influence of the symbiosis on this trait. To this end, we analysed the impact of salt on plant growth, mineral contents, water relations, photosynthetic-related parameters and non-structural sugars in nodulated vs. non-nodulated plants. Although the effects on photosynthesis and stomatal conductance started to become measurable in the presence of 200 mM NaCl, photochemical (e.g., photosynthetic electron flow) and biochemical (e.g., activity of photosynthetic enzymes) parameters were only strongly impaired when NaCl levels reached 600 mM. These results indicate the maintenance of high tissue hydration under salt stress, probably associated with enhanced osmotic potential. Furthermore, the maintenance of photosynthetic assimilation potential (Amax), together with the increase in the quantum yield of down-regulated energy dissipation of PSII (YNPQ), suggested a down-regulation of photosynthesis instead of photo-damaging effects. A comparison of the impact of increasing NaCl levels on the activities of photosynthetic (RubisCO and ribulose-5 phosphate kinase) and respiratory (pyruvate kinase and NADH-dependent malate dehydrogenase) enzymes vs. photosynthetic electron flow and fluorescence parameters, revealed that biochemical impairments are more limiting than photochemical damage. Altogether, these results indicate that, under controlled conditions, C. glauca tolerates high NaCl levels and that this capacity is linked to photosynthetic adjustments.


      PubDate: 2015-08-04T03:52:02Z
       
  • Molecular cloning, expression profiles and characterization of a
           glutathione reductase in Hevea brasiliensis
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Zhi Deng, Manman Zhao, Hui Liu, Yuekun Wang, Dejun Li
      Glutathione reductase (GR; EC 1.8.1.7) is an important oxidoreductase that can protect organisms against various oxidative stresses. In this study, a new GR gene, named as HbGR2, was isolated from Hevea brasiliensis. The HbGR2 cDNA contained a 1674-bp open reading frame encoding 557 amino acids and the deduced HbGR2 protein showed high identities to the chloroplastic GRs from other plant species. HbGR2 was localized in the chloroplasts of tobacco mesophyll protoplasts. The cis-acting regulatory elements related to stress or hormone responses were predicted in the promoter region of HbGR2. The results from real-time RT-PCR analyses showed that HbGR2 was expressed throughout different tissues and developmental stages of leaves. Besides being related to tapping panel dryness (TPD), HbGR2 was regulated by several treatments including ethephon (ET), methyl jasmonate (MeJA), drought, low temperature, high salt, wounding and hydrogen peroxide (H2O2). The Escherichia coli (E. coli) cells overexpressing HbGR2 markedly increased their tolerance and survival at high concentrations of H2O2, suggesting that HbGR2 might play an important role in oxidative stress response in Hevea brasiliensis.


      PubDate: 2015-07-30T20:58:20Z
       
  • New constitutive latex osmotin-like proteins lacking antifungal activity
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Cleverson D.T. Freitas, Maria Z.R. Silva, Frederico Bruno-Moreno, Ana C.O. Monteiro-Moreira, Renato A. Moreira, Márcio V. Ramos
      Proteins that share similar primary sequences to the protein originally described in salt-stressed tobacco cells have been named osmotins. So far, only two osmotin-like proteins were purified and characterized of latex fluids. Osmotin from Carica papaya latex is an inducible protein lacking antifungal activity, whereas the Calotropis procera latex osmotin is a constitutive antifungal protein. To get additional insights into this subject, we investigated osmotins in latex fluids of five species. Two potential osmotin-like proteins in Cryptostegia grandiflora and Plumeria rubra latex were detected by immunological cross-reactivity with polyclonal antibodies produced against the C. procera latex osmotin (CpOsm) by ELISA, Dot Blot and Western Blot assays. Osmotin-like proteins were not detected in the latex of Thevetia peruviana, Himatanthus drasticus and healthy Carica papaya fruits. Later, the two new osmotin-like proteins were purified through immunoaffinity chromatography with anti-CpOsm immobilized antibodies. Worth noting the chromatographic efficiency allowed for the purification of the osmotin-like protein belonging to H. drasticus latex, which was not detectable by immunoassays. The identification of the purified proteins was confirmed after MS/MS analyses of their tryptic digests. It is concluded that the constitutive osmotin-like proteins reported here share structural similarities to CpOsm. However, unlike CpOsm, they did not exhibit antifungal activity against Fusarium solani and Colletotrichum gloeosporioides. These results suggest that osmotins of different latex sources may be involved in distinct physiological or defensive events.


      PubDate: 2015-07-30T20:58:20Z
       
  • Protective effect of UV-A radiation during acclimation of the
           photosynthetic apparatus to UV-B treatment
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Michal Štroch, Zuzana Materová, Daniel Vrábl, Václav Karlický, Ladislav Šigut, Jakub Nezval, Vladimír Špunda
      We examined the acclimation response of the photosynthetic apparatus of barley (Hordeum vulgare L.) to a combination of UV-A and UV-B radiation (UVAB) and to UV-B radiation alone. Our aim was to evaluate whether UV-A radiation prevents UV-B-induced damage to the photosynthetic apparatus and whether UV-A pre-acclimation is required to mitigate the negative influence of UV-B radiation. Barley plants were grown from seeds under low photosynthetically active radiation (50 μmol m−2 s−1) either in the absence or presence of UV-A radiation (UVA− and UVA+ plants, respectively). After 8 days of development, plants were exposed simultaneously to UV-A and UV-B radiation for the next 6 days. Additionally, UVA− plants were exposed to UV-B radiation alone. The UVA+ plants had a higher CO2 assimilation rate near the light-saturation region (AN) and a higher content of both total chlorophylls (Chls) and total carotenoids than the UVA− plants. Chls content, AN, the potential quantum yield of photosystem II (PSII) photochemistry (FV/FM), the capacity of light-induced thermal energy dissipation and the efficiency of excitation energy transfer within PSII remained the same or even increased in both UVA+ and UVA− plants after UVAB treatment. On the contrary, exposure of UVA− plants to UV-B radiation itself led to a reduction in all these characteristics. We revealed that the presence of UV-A radiation during UVAB treatment not only mitigated but completely eliminated the negative effect of UV-B radiation on the functioning of the photosynthetic apparatus and that UV-A pre-acclimation was not crucial for development of this UV-A-induced resistance against UV-B irradiation.


      PubDate: 2015-07-30T20:58:20Z
       
  • Role of phytosterols in drought stress tolerance in rice
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): M.S. Sujith Kumar, Kishwar Ali, Anil Dahuja, Aruna Tyagi
      Phytosterols are integral components of the membrane lipid bilayer in plants. They regulate membrane fluidity to influence its properties, functions and structure. An increase in accumulation of phytosterols namely campesterol, stigmasterol and β-sitosterol was observed in rice as seedlings matured. The levels of the major phytosterol, β-sitosterol in N22 (drought tolerant) rice seedlings was found to increase proportionately with severity of drought stress. Its levels were 145, 216, 345 and 364 μg/g FW after subjecting to water stress for 3, 6, 9 and 12 days respectively, while for IR64 (drought susceptible), levels were 137, 198, 227 and 287 μg/g FW at the same stages. Phytosterols were also found to increase with maturity as observed at 30, 50 and 75 days after planting. The activity of HMG-CoA reductase (EC 1.1.1.34) which is considered to be a key limiting enzyme in the biosynthesis of phytosterols was 0.55, 0.56, 0.78 and 0.85 μmol/min/L at 3, 6, 9 and 12 days of water stress in N22 and 0.31, 0.50, 0.54 and 0.65 μmol/min/L in case of IR64 respectively. The elevation in the levels of phytosterols as well as the activity of HMG-CoA reductase during drought stress indicates the role of phytosterols in providing tolerance to stress.


      PubDate: 2015-07-30T20:58:20Z
       
  • Expression and characterization of a new isoform of the 9 kDa
           allergenic lipid transfer protein from tomato (variety San Marzano)
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Mariateresa Volpicella, Claudia Leoni, Immacolata Fanizza, Sara Rinalducci, Antonio Placido, Luigi R. Ceci
      Lipid transfer proteins (LTPs) are food allergens found first in fruits of the Rosaceae family and later identified in other food plants. Their high structural stability causes them to behave as allergens in cooked and processed foods. Allergenic LTPs have been identified in tomato fruits as well, but studies of their thermal stability and structural characteristics are limited. In this article we report the identification of the coding region for a novel 9 kDa LTP isoform in the tomato variety San Marzano, together with the expression of the recombinant mature protein. The purified recombinant protein was further characterized for its thermal stability and was found to bind 1-palmitoil-2-lysophosphatidylcholine (Lyso-C16) after thermal treatments up to 105 °C. Analysis of a modeling derived structure of the protein allowed the identification of possible epitope regions on the molecular surface.
      Graphical abstract image

      PubDate: 2015-07-30T20:58:20Z
       
  • The effects of anti-DNA topoisomerase II drugs, etoposide and ellipticine,
           are modified in root meristem cells of Allium cepa by MG132, an inhibitor
           of 26S proteasomes
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Aneta Żabka, Konrad Winnicki, Justyna Teresa Polit, Janusz Maszewski
      DNA topoisomerase II (Topo II), a highly specialized nuclear enzyme, resolves various entanglement problems concerning DNA that arise during chromatin remodeling, transcription, S-phase replication, meiotic recombination, chromosome condensation and segregation during mitosis. The genotoxic effects of two Topo II inhibitors known as potent anti-cancer drugs, etoposide (ETO) and ellipticine (EPC), were assayed in root apical meristem cells of Allium cepa. Despite various types of molecular interactions between these drugs and DNA-Topo II complexes at the chromatin level, which have a profound negative impact on the genome integrity (production of double-strand breaks, chromosomal bridges and constrictions, lagging fragments of chromosomes and their uneven segregation to daughter cell nuclei), most of the elicited changes were apparently similar, regarding both their intensity and time characteristics. No essential changes between ETO- and EPC-treated onion roots were noticed in the frequency of G1-, S-, G2-and M-phase cells, nuclear morphology, chromosome structures, tubulin-microtubule systems, extended distribution of mitosis-specific phosphorylation sites of histone H3, and the induction of apoptosis-like programmed cell death (AL-PCD). However, the important difference between the effects induced by the ETO and EPC concerns their catalytic activities in the presence of MG132 (proteasome inhibitor engaged in Topo II-mediated formation of cleavage complexes) and relates to the time-variable changes in chromosomal aberrations and AL-PCD rates. This result implies that proteasome-dependent mechanisms may contribute to the course of physiological effects generated by DNA lesions under conditions that affect the ability of plant cells to resolve topological problems that associated with the nuclear metabolic activities.


      PubDate: 2015-07-30T20:58:20Z
       
  • Effect of molybdenum treatment on molybdenum concentration and nitrate
           reduction in maize seedlings
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Béla Kovács, Anita Puskás-Preszner, László Huzsvai, László Lévai, Éva Bódi
      Since 1940 molybdenum has been known as an essential trace element in plant nutrition and physiology. It has a central role in nitrogen metabolism, and its deficiency leads to nitrate accumulation in plants. In this study, we cultivated maize seedlings (Zea mays L. cv. Norma SC) in nutrient solution and soil (rhizoboxes) to investigate the effect of molybdenum treatment on the absorption of molybdenum, sulfur and iron. These elements have been previously shown to play important roles in nitrate reduction, because they are necessary for the function of the nitrate reductase enzyme. We also investigated the relationship between molybdenum treatments and different nitrogen forms in maize. Molybdenum treatments were 0, 0.96, 9.6 and 96 μg kg−1 in the nutrition solution experiments, and 0, 30, 90, 270 mg kg−1 in the rhizobox experiments. On the basis of our results, the increased Mo level produced higher plant available Mo concentration in nutrient solution and in soil, which resulted increased concentration of Mo in shoots and roots of maize seedlings. In addition it was observed that maize seedlings accumulated more molybdenum in their roots than in their shoots at all treatments. In contrast, molybdenum treatments did not affect significantly either iron or sulfur concentrations in the plant, even if these elements (Mo, S and Fe) play alike important roles in nitrogen metabolism. Furthermore, the physiological molybdenum level (1× Mo = 0.01 μM) reduced NO3–N and enhanced the NH4–N concentrations in seedlings, suggesting that nitrate reduction was more intense under a well-balanced molybdenum supply.


      PubDate: 2015-07-30T20:58:20Z
       
  • Are ineffective defence reactions potential target for induced resistance
           during the compatible wheat-powdery mildew interaction'
    • Abstract: Publication date: November 2015
      Source:Plant Physiology and Biochemistry, Volume 96
      Author(s): Ch. Tayeh, B. Randoux, B. Tisserant, G. Khong, Ph. Jacques, Ph. Reignault
      Powdery mildew caused by Blumeria graminis f.sp. tritici, an obligate aerial biotrophic fungus, would be one of the most damaging wheat (Triticum aestivum) diseases without the extensive use of conventional fungicides. In our study, the expression levels of some basal defence-related genes were investigated during a compatible interaction in order to evaluate wheat reactions to infection, along with the different stages of the infectious process in planta. As fungal conidia initiated their germination and developed appressorial germ tube (AGT), early defence reactions involved the expression of a lipoxygenase (LOX)- and an oxalate oxidase (OXO)-encoding genes, followed by activations of corresponding LOX (EC 1.13.11.12) and OXO (EC 1.2.3.4) activities, respectively. When penetration of AGT took place, up-regulation of chitinases (CHI) and PR1-encoding genes expression occurred along with an increase of CHI (EC 3.2.1.14) activity. Meanwhile, expression of a phenylalanine ammonia-lyase-encoding gene also took place. Up-regulation of a phospholipase C- and lipid transfer proteins-encoding genes expression occurred during the latest stages of infection. Neither the phi glutathione S-transferase (GST)-encoding gene expression nor the GST (EC 2.5.1.13) activity was modified upon wheat infection by powdery mildew. Whether these defence reactions during such a compatible interaction are markers of immunity or susceptibility, and whether they have the ability to contribute to protection upon modulation of their timing and their intensity by resistance inducers are discussed.


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


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


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


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


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


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




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


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


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


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


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


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


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


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


      PubDate: 2015-07-05T14:16:59Z
       
  • Thyme essential oil as a defense inducer of tomato against gray mold and
           Fusarium wilt
    • Abstract: Publication date: September 2015
      Source:Plant Physiology and Biochemistry, Volume 94
      Author(s): Maissa Ben-Jabeur , Emna Ghabri , Machraoui Myriam , Walid Hamada
      The potential of thyme essential oil in controlling gray mold and Fusarium wilt and inducing systemic acquired resistance in tomato seedlings and tomato grown in hydroponic system was evaluated. Thyme oil highly reduced 64% of Botrytis cinerea colonization on pretreated detached leaves compared to untreated control. Also, it played a significant decrease in Fusarium wilt severity especially at7 days post treatment when it was reduced to 30.76%. To explore the plant pathways triggered in response to thyme oil, phenolic compounds accumulation and peroxidase activity was investigated. Plant response was observed either after foliar spray or root feeding in hydroponics which was mostly attributed to peroxidases accumulation rather than phenolic compounds accumulation, and thyme oil seems to be more effective when applied to the roots.
      Graphical abstract image

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


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


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


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


      PubDate: 2015-07-01T14:00:39Z
       
 
 
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