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Environmental and experimental botany
Pergamon Press,
Environmental and experimental botany

Pergamon Press,

0098-8472

Environmental and experimental botany/Journal Environmental and experimental botanySCIISTP
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    Differential response of rice genotypes to nitrogen availability is associated with the altered nitrogen metabolism and ionomic balance

    Kumar, AmreshPandey, AshutoshSinha, Subodh KumarSingh, Amar Pal...
    14页
    查看更多>>摘要：Nitrogen (N) uptake and its assimilation are crucial steps for plant growth and productivity. Plant's N balance largely depends on nitrate (NO3-) and ammonium (NH4+) forms present in the rhizosphere. Due to the fluctuating and heterogeneous availability of these N forms in the soils, plants encounter low to N deficiency. In contrast to low nitrogen, high N in the form of ammonium (NH4+) severely hampers plant development and causes NH4+ toxicity. In this study, we assessed eleven rice genotypes under sufficient (SN) and low N (LN) conditions. From the analysis, we identified a rice genotype, PB1, which is hypersensitive to SN and showed reduced root and shoot growth. In contrast to the SN condition, PB1 showed improved growth performance under the LN con-dition. Our data show that compromised growth of PB1 under SN condition is associated with increased activity of N responsive genes such as OsAMT1.1, OsAMT2.3, OsAMT3.1 and OsAMT3.2, OsNRT1.1A and OsNRT1.1B. Strikingly, LN treatment improved the root and shoot biomass with a concomitant increase in levels of NO3- and NH4+ transporter genes along with an increase in shoot: root NO(3)(- )ratio. Additionally, we show that increased levels of N in PB1 under SN condition are associated with the enhanced activity of the GS-GOGAT pathway. Further, our ionomic analysis highlighted the role of N-defined Fe accumulation which is partially associated with the N toxicity. Taken together, our study led to identifying a rice genotype (Oryza sativa L.) which is associated with enhanced N levels and assimilation and could be used for raising N use efficient rice varieties using breeding approaches.
      原文链接:
    • NSTL
    • Elsevier

    Silicon mitigates potassium deficiency by enhanced remobilization and modulated potassium transporter regulation

    Beier, SaraMarella, Nara C.Yvin, Jean-Claudevon Wiren, Nicolaus...
    17页
    查看更多>>摘要：Silicon (Si) improves plant growth and development especially under stress conditions. Although Si alleviates growth suppression and deficiency symptoms of several nutrient disorders, underlying regulatory processes have remained indefinite. Here, we analyzed the impact of Si on nutritional, metabolic and transcriptional responses in roots and shoots of barley subjected to potassium (K) deficiency. On the long run, Si nutrition improved root and shoot growth as well as metabolite homeostasis and partly reverted the K deficiency signature of the transcriptome back to adequate only in fully expanded leaves but hardly in roots. In the short term, Si supply to K-starved roots enhanced first the expression of the vacuolar K exporter KCO1 together with root-to-shoot translocation rates of rubidium (Rb) that was used as tracer for K. The typical K deficiency response, marked by upregulation of the K importer genes HAK1 and AKT1, set in a few days later but then at several-fold higher levels. Lower root K and higher shoot K contents in Si-supplied plants indicated more efficient remobilization of root K pools and higher root-to-shoot translocation, which on the long run restored K-dependent metabolic processes in shoots for the sake of continued assimilate provision to roots. These results provide a sequence of physiological processes by which Si partially recovers plants from K deficiency and indicate that Si interferes with systemic K deficiency signaling in roots to alter the regulation of K transporters.
      原文链接:
    • NSTL
    • Elsevier

    TaMYC8 regulates TaERF6 and inhibits ethylene synthesis to confer Cd tolerance in wheat

    Wang, HongchengZuo, DanZhu, BinDu, Xuye...
    9页
    查看更多>>摘要：Cadmium (Cd) is a toxic, nonessential heavy metal; its accumulation in plants alters metabolism and limits productivity. Although various studies have addressed the Cd stress response in various species, the detailed molecular mechanisms remain unknown. Therefore, the present work investigated the influence of the TaMYC8 transcription factor (TF) on the Cd-induced stress response in wheat. The present study found that TaMYC8 is a nuclear protein highly induced in the roots under Cd stress. Overexpression of TaMYC8 in the wheat cultivar 'Bobwhite' increased sensitivity to Cd stress, probably due to the increased levels of superoxide (O2.-), malo-naldehyde (MDA), jasmonic acid (JA), and Cd, and reduced the proline content and antioxidant enzyme activity. In contrast, silencing TaMYC8 via RNA interference (RNAi) significantly lowered Cd accumulation and improved Cd tolerance. Using the yeast one-hybrid assay (Y1H), chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR), electrophoretic mobility shift assay (EMSA), and dual luciferase reporter assay, it was found that TaMYC8 could physically bind to the TaERF6 promoter and activate TaERF6 transcription. More importantly, knockdown of TaMYC8 by RNAi inhibited the activities of 1-aminocyclopropane-1-carboxylic (ACC) acid synthase (ACS) and ACC oxidase (ACO) of the ethylene biosynthetic pathway. In conclusion, TaMYC8 promotes TaERF6 transcription and affects the ethylene biosynthetic pathway. These findings provide a theo-retical basis for breeding low-Cd-accumulating wheat cultivars.
      原文链接:
    • NSTL
    • Elsevier

    GRAS-type transcription factor CaGRAS1 functions as a positive regulator of the drought response in Capsicum annuum

    Oh, DonghyukLim, Chae WooLee, Sung Chul
    11页
    查看更多>>摘要：Transcription factor-mediated gene expression is essential for the regulation of most cellular processes, including the responses to abiotic and biotic stresses. Although a range of plant-specific GRAS transcription factors are involved in stress responses, their precise biological functions in pepper (Capsicum annuum) have yet to be ascertained. In this study, we isolated 10 pepper GRAS genes belonging to the PHYTOCHROME A SIGNAL TRANSDUCTION1 (PAT1) subfamily and identified the CaGRAS1 protein as being highly induced by abscisic acid (ABA), dehydration, and/or salt stress treatments. CaGRAS1 harbors a GRAS domain in the C-terminal region and an acidic domain in the N-terminal region, which have transcriptional activities. CaGRAS1-overexpressing (OX) Arabidopsis plants were found to show ABA-sensitive and drought-resistant phenotypes, whereas compared with wild-type plants, CaGRAS1-OX plants showed no specific phenotypic differences under high salt stress conditions. In contrast, CaGRAS1-silenced pepper plants exhibited a drought-sensitive phenotype characterized by ABA insensitivity. Furthermore, compared with control plants, we found that in response to drought stress, the expression patterns of Arabidopsis and pepper stress-responsive genes showed greater induction and reduction in CaGRAS1-OX and CaGRAS1-silenced plants, respectively. Collectively, our findings indicate that CaGRAS1 acts as a positive regulator in drought resistance by controlling the expression of stress-responsive genes.
      原文链接:
    • NSTL
    • Elsevier

    Adjusting leaf nitrogen allocation could promote photosynthetic capacity, and nitrogen accumulation in Cucumis sativus L.

    Qu, FengPeng, TieliJia, YuanjieYang, Mingfei...
    13页
    查看更多>>摘要：Nitrogen (N) is essential for crop growth and development under stress. The photosynthetic capacity of crops depends on the leaf N content (N-a), and leaf N allocation is an important factor affecting net photosynthetic rate (P-n). However, the relationship between N supply and leaf N allocation and the effects of different N forms on cucumber growth at low-temperature (LT) stress are still unclear. In this study, the effects of different N concentrations (NC) and ammonium (NH4+)-nitrate (NO3-) ratios (A-NR) supplied to grown LT-stressed cucumber at seedling and flowering to early fruiting stages on growth, photosynthesis, N accumulation, and leaf N allocation were assessed. NC, A-NR, and their interactions significantly affected leaf area, P-n, chlorophyll content, and N accumulation at seedling and flowering to early fruiting stages. When the cucumber plants were grown in LT environment, the maximum photochemical efficiency, leaf area, P-n, chlorophyll content, N-a, water-soluble proteins N (N-w), and N accumulations in various organs were the greatest. The content of sodium dodecyl sulfate (a detergent) soluble protein N (N-s) was minimal when the NCs at the seedling and flowering to early fruiting stages were 10.5 and 28 mmol.L-1, respectively, and the A-NRs were both 1:1. Correlation analysis showed that leaf area, P-n, chlorophyll content, and N accumulation could be improved by increasing N-a and N-w or reducing N-s. This finding suggested that increasing NC and NH4+ proportion in the nutrient solution could increase N-a and N-w in leaves and reduce the content of N-s, thereby improving photosynthetic capacity to promote leaf growth and increasing cucumber LT resistance.
      原文链接:
    • NSTL
    • Elsevier

    Stronger ability to absorb nitrate and associated transporters in the invasive plant Xanthium strumarium compared with its native congener

    Luo, Jia-JunGao, Ying-MeiFeng, Wei-WeiLiu, Ming-Chao...
    9页
    查看更多>>摘要：Nitrogen (N) is the limiting factor for plant growth in natural ecosystems, and increasing soil N availability often promotes exotic plant invasions. However, few studies have considered the effects of N forms. In this study, we tested the hypothesis that Xanthium strumarium, a noxious invader in disturbed habitats (generally with nitrate as dominant soil N form), may have higher N uptake rates and therefore higher biomass production under nitrate treatments than its co-occurring native congener X. sibiricum. We also determined the nitrate transporters associated with the stronger nitrate uptake ability of the invader. We first compared N uptake rates and biomass production between and within these species under different N forms and levels, and then conducted the PacBio and HiSeq sequencings. Consistent with our hypothesis, the invader had significantly stronger nitrate uptake ability than its native congener and its own ammonium uptake ability. Similar patterns were also found for total biomass. Six of the seven highly expressed common NPF transcripts, especially XstNPF6.2a, XstNPF6.1b and XstNPF3.1a, and three highly expressed common NRT2 transcripts (XstNRT2.9c, XstNRT2.8c and XstNRT2.9d) may all contribute to the stronger nitrate uptake ability of the invader. The highly expressed unique transporters such as XstNPF6.2b, XstNPF6.1a, XstNPF6.2c, XstNPF6.2d, XstNPF5.2, XstNPF7.2, XstNRT2.5a, XstNRT2.4 and others may also contribute to the stronger nitrate uptake ability of the invader. Our results explain the mechanisms of interspecific differences in phenotypic plasticity and hence exotic plant invasions at a molecular level, and indicate that invasiveness of X. strumarium may be aggravated in the future under the background of global change.
      原文链接:
    • NSTL
    • Elsevier

    RmZAT10, a novel Cys2/His2 zinc finger transcription factor of Rosa multiflora, functions in cold tolerance through modulation of proline biosynthesis and ROS homeostasis

    Luo, PingChen, LinmeiChen, YeniShen, Yuxiao...
    15页
    查看更多>>摘要：The Cys2/His2-type (C2H2) zinc finger transcription factor (TF) consists of a significant gene family that has an effect on development process regulation and a wide range of stress responses, whereas the roles and regulatory pathways of the majority of C2H2-type zinc finger TFs remain unclear. Here, we characterized a C2H2-type zinc finger TF (RmZAT10) from Rosa multiflora. RmZAT10 was mainly expressed in leaves and located in the nucleus. RmZAT10 was rapidly up-regulated during dehydration, cold as well as ABA treatment, with the maximal induction under cold stress. RmZAT10 overexpression facilitated the cold tolerance of tobacco, while gene silencing caused by virus-induced gene silencing (VIGS) of RmZAT10 within R.multiflora led to elevated cold sensitivity. Transgenic tobacco accumulated a larger amount of proline, consistent with elevated the expression level of P5CS (delta-1-pyrroline-5-carboxylate synthetase). Nevertheless, the VIGS plant achieved the opposing trend. The treatment using 24-epi-brassinolide caused transgenic tobacco plants more sensitive to cold, while exogenous proline partially restored cold tolerance of the VIGS plants. In addition, RmZAT10 could bind specifically to and activate the promoter of RmP5CS. The above results revealed the role played by RmZAT10 in cold tolerance through the modulation of proline biosynthesis and ROS homeostasis.
      原文链接:
    • NSTL
    • Elsevier

    OsSPL14 is involved in nitrogen-deficiency-induced root elongation in rice

    Wang, BoboGuo, XiaoliQi, XuejiaoFeng, Fan...
    8页
    查看更多>>摘要：Nitrogen (N) is an essential element for rice (Oryza sativa L.) growth. Rice responds to N-limiting conditions by changing root morphology. Strigolactones (SLs) and auxin modulate rice root elongation under N-deficient conditions. However, the interactions between SLs and auxin in the regulation of root elongation in response to N deficiency remain needing further study. Here, we analysed the function of SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 14 (SPL14, a downstream transcription factor of strigolactone signaling) in regulating root elongation under low N (LN) supply. Compared with sufficient N (SN) condition, LN and SN+GR24 (SL analogue) reduced protein interaction between SLs signaling repressor DWARF 53 (D53) and SPL14. The expression of SPL14 was induced by LN supply. In contrasts to WT plants, knockdown of SPL14 resulted in less extensive changes in root length under LN condition. Overexpression of SPL14 under SN supply enhanced root length to the same extent as WT plants under LN condition, suggesting that SPL14 was induced by LN condition and led to changes in root elongation. The transcription of PIN-FORMED 2 and 10b (auxin efflux carriers) were negatively and positively regulated by SPL14, respectively. Under SN and LN conditions, similar root morphology was observed in overexpressing PIN10b and SPL14 lines, and opposite root phenotypes were recorded between pin2 mutants and SPL14-RNAi lines.These results indicated that PIN2 and PIN10b were involved in SPL14-induced root elongation under LN condition. Therefore, we presented that, LN inhibits D53 and SPL14 interaction, which releases SPL14 to modulate the transcription of PIN2 and PIN10b, resulting in root elongation in rice.
      原文链接:
    • NSTL
    • Elsevier

    Induced accumulation of chloroplastic and mitochondrial reactive oxygen species (ROS) differentially regulates the enzymatic antioxidant system of C-3 Flaveria robusta and C-4 F. bidentis

    Ozgur, RenginUzilday, BarisYalcinkaya, TolgaTurkan, Ismail...
    10页
    查看更多>>摘要：C-4 plants are acclimated to drought and high temperatures that are detrimental for C-3 plants, and they are well equipped with a better antioxidant capacity to cope with oxidative stress caused by abiotic stresses. However, how C-3 and C-4 plants respond to oxidative stress that occurs in a specific compartment of the cell, such as chloroplast or mitochondria, is still not known. Therefore, understanding antioxidant responses of different carboxylation pathways to reactive oxygen species (ROS) at organelle level deserves an investigation. In the present study, the production of organelle originated ROS was induced with chemical agents specific to mitochondria (rotenone =ROT) and chloroplasts (methyl viologen = MV and DCMU), and antioxidant response of Flaveria robusta (C-3) and F. bidentis (C-4) were studied. For this purpose, activities of antioxidant system (superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductases (GR)), and isoenzymes of SOD, CAT, and NADPH oxidase (NOX) activity were determined. Treatment of leaves with ROT, MV and DCMU for 4 h induced lipid peroxidation by 38%, 18% and 41% respectively in F. robusta, while 81%, 75% and 56% induction were observed for same inhibitors in F. bidentis. On the other hand, treatment with inhibitors cause decrease of CAT activity in F. robusta (27% with ROT), while increased CAT activity was observed in F. bidentis (maximum 68% with MV). Overall, the antioxidant defense responses of C3 and C-4 plants were distinctive to organelle induced oxidative stress, especially in chloroplast-sourced accumulation of ROS.
      原文链接:
    • NSTL
    • Elsevier

    Analysis of Lhcb gene family in rapeseed (Brassica napus L.) identifies a novel member "BnLhcb3.4" modulating cold tolerance

    Zhang, YiRaza, AliHuang, HeSu, Wei...
    13页
    查看更多>>摘要：The light-harvesting chlorophyll a/b-binding proteins (Lhcb) constitute the antenna system of the photosynthetic apparatus that has an essential function in photosynthesis and modulating stress responsiveness. In this study, we identified 35 Lhcb genes (BnLhcbs) in the rapeseed (Brassica napus L.) genome, which were clustered into 8 groups. The BnLhcb genes were distributed on 15 chromosomes of rapeseed; the subsequent analysis of gene structures showed that these members were highly conserved. Based on the importance of Lhcbs for plant defense against abiotic stresses, responses of BnLhcbs to cold stress were analyzed using cold-tolerant and-sensitive rapeseed cultivars. The BnLhcb genes exhibited distinct expression patterns, among which, BnLhcb3.4 was dramatically induced in the tolerant cultivar and down-regulated in the sensitive cultivar. Furthermore, the cDNA sequences of the BnLhcb3.4 gene was successfully cloned, the subcellular investigation confirmed that BnLhcb3.4 localized in chloroplast. The transgenic analysis indicated that overexpression of the BnLhcb3.4 gene significantly enhanced the freezing tolerance of transgenic Arabidopsis, together with increased abscisic acid (ABA) sensitivity. In addition, a set of ABA-responsive genes were altered in the transgenic plants. Taken together, these data demonstrate that BnLhcb3.4 may contribute to cold tolerance by evolving ABA signaling pathway.
      原文链接:
    • NSTL
    • Elsevier