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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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    A novel salt responsive PvHAK16 negatively regulates salt tolerance in transgenic Arabidopsis thaliana

    Dai, MengtongHuang, RishengHan, YiyangZhang, Ziyi...
    11页
    查看更多>>摘要：HAK/KUP/KT transporters play an important role in maintaining K+ and Na+ homeostasis in plants in response to salt stress. A salt induced PvHAK16 from halophyte seashore paspalum (Paspalum vaginatum O. Swartz) was identified in this study. PvHAK16 was localized in the plasma membrane and highly expressed in leaves but not in roots. Overexpression of PvHAK16 in Arabidopsis led to reduced seed germination rate, shoot weight, F-v/F-m and survival rate but increased ion leakage after salt stress as compared with the wild type. Increased Na+ and decreased K+ levels that led to higher Na+/K+ ratio was observed in transgenic lines after salt stress, which was a result of the net influx of Na+ and net efflux of K+ in transgenic plants. The results suggest that PvHAK16 confers Na+ uptake and K+ efflux under salt stress and thus negatively regulates salt tolerance. Moreover, PvHAK16 expression altered transcript levels of ion homeostasis genes K+-Uptake Permease 7 (KUP7), Potassium Transport 2/3 (AKT2), Salt Overly Sensitive 1 (SOS1) and Gated Outwardly-Rectifying K+ Channel (GORK), which were associated with the increased Na+/K+ ratio in transgenic plants. Transgenic plants had reduced transcript levels of stress responsive genes and showed promoted oxidative damage as a result of reduced SOD activity and proline accumulation.
      原文链接:
    • NSTL
    • Elsevier

    Contribution of plant miRNAome studies towards understanding heavy metal stress responses: Current status and future perspectives

    Ghosh, SupriyaAdhikari, SinchanAdhikari, AyanHossain, Zahed...
    21页
    查看更多>>摘要：Heavy metal toxicity has been identified as a major issue of global concern. Presence of excessive amount of heavy metals (HMs) and metalloids in agricultural soil adversely affects plant growth and productivity. Micro-RNAs (miRNAs) are evolutionarily conserved set of tiny (20-24 nucleotides), non-coding RNA molecules that regulate gene expression at post-transcriptional level. Stress induced miRNAs confer tolerance against heavy metals by targeting the negative regulators of stress tolerance, while their downregulation lead to higher accumulation of positive regulators. Advancement in next generation sequencing technology has made micro-RNAomic a fast, sensitive and reliable technique for identification and characterization of large number of stress responsive miRNAs. Development of user-friendly bioinformatics software enable researchers to precisely identify the target genes of HMs responsive miRNAs which are found to be associated with diverse biological processes including plant growth and development, redox homeostasis, hormone signaling, HMs transport and detoxification pathways. Present review highlights contributions of sRNA transcriptomic studies over a 15-year period (2006-2020) towards understanding the miRNA-gene modules to comprehend the complex mechanisms of HMs stress responses in plant. Moreover, challenges and future prospects are discussed in detail to get new insights into the different strategies of HMs detoxification and tolerance mechanisms in plants.
      原文链接:
    • NSTL
    • Elsevier

    Salt interferences to metabolite accumulation, flavonoid biosynthesis and photosynthetic activity in Tetrastigma hemsleyanum

    Yang, LiShi, YanshouRuan, XiaoWu, Qingfei...
    12页
    查看更多>>摘要：This work mainly investigated the interferences of NaCl treatment to major metabolite accumulation, individual flavonoid biosynthesis and photosynthetic activity in Tetrastigma hemsleyanum. The results showed that the accumulation of phenolic acids, steroids and polysaccharides in T. hemsleyanum was significantly enhanced after the treatment of 50 or 100 mM NaCl for 12 days, and after 150 mM NaCl treatment for 3 days, the total content of flavonoids reached the highest value of 219.5 mu g.g(-1-1) and was higher by 3.8 times in comparison with the control (CK). In addition, the salt stress would generally enhance the reaction selectivity of Path II (RPSII) to produce flavonol derivatives (Rut, IsoQ, Km3rut, Ast, Qu, Km) and reduce the reaction selectivity of Path I (RPSI) to produce flavone derivatives (IsoO, Or, Ap), and after the treatment of 150 mM NaCl for 3 days, the RPSII and the RPSI reached the highest level of 0.785 and the lowest level of 0.215, respectively. Moreover, salt stress demonstrated significant and diverse effects on photosynthetic characteristics of T. hemsleyanum. Compared with CK, the values of Pn, Cond, Tr, Fv/Fm, Y(II) and qP increased first and then declined with increasing NaCl concentration and stress time, and the highest level of Pn, Fv/Fm and Y(II)occurred after 50 mM NaCl treatment. These findings clearly showed that 50 mM NaCl treatment results in favorable changes in photosynthesis and secondary metabolites accumulation in T. hemsleyanum.
      原文链接:
    • NSTL
    • Elsevier

    Development of suberized barrier is critical for ion partitioning between senescent and non-senescent tissues in a succulent halophyte Sarcocornia quinqueflora

    Ahmed, Hassan Ahmed IbraheemShabala, SergeyGoemann, KarstenShabala, Lana...
    11页
    查看更多>>摘要：Senescence of plant tissues is a physiologically synchronized process that enables an evergreen or a perennial plant to retrieve, recycle and remobilize nutrients from elder to younger tissues or upcoming seeds. The succulent perennial halophyte S. quinqueflora utilizes this process to discard excess salt being accumulated in outer tissues of their leafy stems. The exact mechanism for salt shedding in this plant, however, remains elusive. In this work we show that the plant develops two distinct types of tissues - an endodermis-like layer (suberized layer, ED), and an additional internal photosynthetic layer (IP) - to enable this process. Their potential roles toward salt-coping strategy were investigated in this study. We show that elevated salinity leads to an accelerated development of the ED, and that its development strongly affected ion partitioning between outer (senescent) and inner (nonsenescent) tissues. A positive correlation between the ratio of ED to a bead diameter and the outer to inner concentration of Na+ was observed. These ratios were highest in older (basipetally-located) beads and progressively decreased towards the tip. Furthermore, the Na+/K+ ratio in inner tissues of bottom beads at highest salinity treatments (800 and 1000 mM NaCl) that showed clear senescence symptoms was similar to 1.0, indicative of complete separation of the outer and inner tissues at late developmental stage due to the fully suberized ED multilayer. A dual-sources: dual-sinks model explaining the role of the IP layer in plant adaptation to salinity is presented.
      原文链接:
    • NSTL
    • Elsevier

    H3K4me2, H4K5ac and DNA methylation function in short- and long-term heat stress responses through affecting the expression of the stress-related genes in G. hirsutum

    He, ShibinZhang, YaqiWang, JiWang, Yan...
    13页
    查看更多>>摘要：High temperature or heat stress (HS) is becoming a major threat to plant growth and crop production due to global warming. Plant adaptation to HS is markedly affected by epigenetic modifications like histone modifications and DNA methylation. However, the roles of the epigenetic modifications in modulating the responses to HS in cotton seedlings are largely unknown. In this study, the effects of short- and long-term HS on seedling growth, and the functions of histone modifications and DNA methylation in cotton responding to HS were investigated. The results showed that HS led to marked inhibition of growth, accompanied with changes in the transcript abundances of many HS-related genes and those in the contents of H3K4me2 and H4K5ac. Moreover, changes in H3K4me2 and H4K5ac levels were associated with those in the expression levels of multiple HSresponsive genes including GhHSFA1a (Heat shock factor A1a), GhHSFA2, GhHSP3 (Heat shock protein 3), GhRBCS (Small subunit of rubisco), GhERF1A (Ethylene response factor 1A) and GhHXK1 (Hexokinase 1) under high temperature stress. Also, alterations in DNA methylation levels were associated with those in the expression levels of GhHSFA1a upon HS. ChIP-qPCR results revealed that H3K4me2 levels elevated upon short-term HS, and H4K5ac levels raised during the whole HS process, particularly upon long-term HS. Virus-induced gene silencing (VIGS) experiments demonstrated that GhHSFA1a and GhHSFA2 positively, and GhERF1A and GhHXK1 negatively regulated HS tolerance in cotton. Collectively, these results suggest that H3K4me2, H4K5ac and DNA methylation modulate the expression of the HS-related genes, contributing to thermotolerant regulation in G. hirsutum.
      原文链接:
    • NSTL
    • Elsevier

    The mitogen-activated protein kinase kinase MKK2 positively regulates constitutive cold resistance in the potato

    Kou, ShuangLiu, TiantianDong, JiankeTu, Wei...
    10页
    查看更多>>摘要：Cold stress is a detrimental environmental factor affecting plant growth and development. The mitogen-activated protein kinase (MAPK) cascade pathway mediates various signalling pathways associated with abiotic stress tolerance in plants. In this research, 15 MAPKs, 5 MAPKKs and 83 MAPKKKs in the potato genome were iden-tified by comparative genomics analysis and named following the Arabidopsis MAPK nomenclature model. The differentially expressed genes in response to cold stress between S. acaule and S. tuberosum were enriched in the MAPK cascade pathway. Quantitative real-time PCR (qRT-PCR) results revealed that the expression of SaMKK2 and SaMAPK16 particularly increased in the cold-tolerant S. acaule. Additionally, the promoters of StMKK2 and SaMKK2 differ largely in cold responsive motifs. Compared with wild-type E3, transgenic lines overexpressing SaMKK2 exhibited dramatic improvement of constitutive cold resistance in the potato, indicating that the function of MKK2 is species-dependent. However, SaMAPK16 overexpression had no effects on either cold resistance without or with cold acclimation. Furthermore, the transcriptome and qRT-PCR data showed that overexpression of SaMKK2led to a significant increase in the expression of CBF1/2/3, OPR2 and SLD2 after cold treatment for two hours compared with wild-type under cold stress. The results of yeast two-hybrid and bimo-lecular fluorescence complementation experiments together suggested that SaMKK2 interacted with SaMAPK4/7 and that the interaction occurred in the cytoplasm. Given these results, we concluded that the interaction be-tween SaMKK2 and SaMAPK4/7 may positively promote the expression of CBFs, OPR2 and SLD2, which even-tually increases the constitutive cold resistance of potato.
      原文链接:
    • NSTL
    • Elsevier

    Coordinated regulation of photosynthesis and sugar metabolism in guar increases tolerance to drought

    Pandey, KomalKumar, Ravi ShankarPrasad, PritiTrivedi, Prabodh Kumar...
    16页
    查看更多>>摘要：Drought is an inevitable environmental constraint to plant productivity. Cyamopsis tetragonoloba commonly known as guar is an economically important crop used as vegetable, and for its seed gum. We examined the complicated network of sugar interactions and regulation of photosynthesis in four varieties of guar subjected to water stress. A presumptive mechanistic approach considering growth and development, physiological attributes, and gene expression facet was evaluated. Decreased photosynthesis results in reduced equivalents (NADPH(2)(+)) for CO2 assimilation through the Calvin cycle, which furthermore generates oxidative stress and accumulates antioxidant enzymes. The scavenging of ROS was more in RGC-986 and HG-563 than RGC-471 and Varsha variety. Chlorophyll fluorescence studies indicate a significant reduction in values of photochemical quantum yield, electron transport rates of photosystem I and II, photochemical quantum yield due to regulated energy dissipation, and fraction of energy that is passively dissipated in the form of heat and fluorescence. For a better understanding of the behavioural pattern in response to drought, we studied the relative gene expression of enzymes regulating the sugar metabolism. The study suggested that at the onset of drought the genes of PS II machinery and Calvin cycle were co-ordinately regulated efficiently in RGC-986 and HG-563 than in RGC-471 and Varsha. However, the gene expression levels of sugar transporter enzymes in leaves of guar varieties increased under water stress. Gene expression analysis of sugar metabolic pathways reveals the increased production of glucose, fructose and fructan in HG-563 and RGC-986 in comparison to Varsha and RGC-471. These results indicate that induced level of sugar metabolic genes under drought leads to the activation of its tolerance mechanism. Furthermore, this study significantly highlights that how carbon flux is diverted to sugar metabolism via a sequence of molecular events in relation to its physiological status, under water deficit conditions in guar leaves.
      原文链接:
    • NSTL
    • Elsevier

    Interaction of wheat methionine sulfoxide reductase TaMSRB5.2 with glutathione S-transferase TaGSTF3-A contributes to seedling osmotic stress resistance

    Zhao, WanmeiDing, PengchengGuo, QiangHu, Dandan...
    13页
    查看更多>>摘要：Reactive oxygen species (ROS) produced due to drought stress can lead to the oxidation of methionine in plant cells; this can then be reduced by methionine sulfoxide reductases (MSRs). To the best of our knowledge, no information has been reported to date on the function and substrates of wheat cytoplasmic TaMSRB5.2, which is induced by drought mainly both in the leaves and roots. In the present study, its constitutive overexpression in wheat (TaOE) resulted in a notable increase in MSR activity, and enhanced the tolerance of seedlings, particularly to osmotic stress, but also to salt stress. The effects of constitutively active TaMSRB5.2 in wheat included a decrease in ROS accumulation, a heightening of endogenous abscisic acid (ABA) levels, an increase in the sensitivity of stomatal guard cells to exogenous ABA, and an enhancement of intracellular proline content. Wheat glutathione S-transferase F3-A (TaGSTF3-A), a potential interaction substrate of TaMSRB5.2, was identified by screening a wheat cDNA library, and further confirmed by means of yeast two-hybrid, split-luciferase complementation and co-immunoprecipitation assays. Under osmotic stress, TaGSTF3-A expression, overall GST enzyme activity and the ratio of GSH/GSSG in the TaOE lines increased, compared to the wild-type strain. L-buthionine sulfoximine, a GST inhibitor, was found to partially impair the TaMSRB5.2-induced response to osmotic stress. TaMSRB5.2 and TaGSTF3-A were observed to be expressed in the leaves, their proteins localized within the cytoplasm, and both acted in abiotic stress response, according to the present and previous studies. In conclusion, TaMSRB5.2 participates in osmotic response in wheat, partially via TaGSTF3-A.
      原文链接:
    • NSTL
    • Elsevier

    Genome-wide analysis of lectin receptor-like kinases (LecRLKs) in sweet cherry (Prunus avium) and reveals PaLectinL16 enhances sweet cherry resistance with salt stress

    Sun, YaoZhao, XiaohuiGao, YuanhuiJiao, Jiao...
    13页
    查看更多>>摘要：Lectin receptor-like kinases (LecRLKs) belong to the large subfamily of receptor like kinases (RLKs), which play a critical role in plant development and innate immunity. However, knowledge about the LecRLKs in sweet cherry and its function to against adverse environmental stresses are lacking. In this study, we identified 161 PaLecRLKs genes in the genome of sweet cherry. Phylogenetic analysis showed that PaLecRLKs proteins can be divided into three types, including L-type (50), G-type (110), and C-type (1). Analysis of gene expression patterns showed that most of the L-type PaLecRLKs genes were highly expressed under biotic and abiotic stresses. Functional study found that overexpression PaLectinL16 in Arabidopsis could enhance its resistance with abiotic (salt, drought) stresses. Moreover, PaLectinL16 overexpression also improved the salt tolerance of transgenic sweet cherry rootstock Gisela 6 through increasing the activities of ROS scavenging enzymes and up-regulation the related genes. This study offers a comprehensive view of PaLecRLKs in sweet cherry and sheds light on potential roles with external environmental stresses.
      原文链接:
    • NSTL
    • Elsevier

    Maternal light environment interacts with genotype in regulating seed photodormancy in tobacco

    Dong, ShuaiLiu, Yi lingZhang, MinZhang, Jie...
    10页
    查看更多>>摘要：The environment experienced by tobacco seeds during maturation affects subsequent germination. However, its molecular mechanism is poorly understood. This study aimed to reveal the effects of maternal light environment, genotypes, and their interactions on seed photodormancy in tobacco. The results showed that freshly harvested seeds (FS) of majority varieties (strong-photodormant type, dark-germination of FS is less than 50%) in tobacco could not germinate in the dark, while seeds of minority varieties (shallow-photodormant type, dark-germination of FS is more than 50%) that matured in some environments could germinate independent of light and did not require the duration of after-ripening. The transcriptome comparisons of strong-and shallow-photodormant seeds revealed that the expression of genes involved in light-activated plant hormone signals for strong-photodormant seeds showed opposite changes when the seeds were incubated under light and in the dark. NtPHYB1K326, a homologous gene of Arabidopsis thaliana (Arabidopsis) phytochrome B (PHYB) that in the light-activated plant hormone signals pathway during seed germination, was investigated in this study. The germi-nation frequency of NtPHYB1K326 overexpressing (NtPHYB1K326-OE) seeds was higher than that of wild type (WT) and NtPHYB1K326 RNA interference (NtPHYB1K326-RNAi) seeds in the dark. Interestingly, seed germination in the dark was strongly influenced by the light environment. The seeds showed more germination in the dark when mother plants matured under shading environments than under natural environments. Different types of photodormant seeds or NtPHYB1K326-transgenic seeds showed similar results. These findings illustrated that seed photodormancy could be a heritable trait but was strongly influenced by the light environment of maternal plant development.
      原文链接:
    • NSTL
    • Elsevier