Publications of NIPGR Scientists

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Author: search.filters.author.Sinha, Alok KrishnaSubject: search.filters.subject.Oxidative stress

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    Unraveling the molecular aspects of iron-mediated OsWRKY76 signaling under arsenic stress in rice
    (Elsevier B.V., 2023) Mirza, Zainab; Jonwal, Sarvesh; Saini, Himanshu; Sinha, Alok Krishna; Gupta, Meetu
    Arsenic (As) is a significant environmental element that restricts the growth and production of rice plants. Although the role of iron (Fe) to sequester As in rice is widely known, the molecular mechanism regarding As–Fe interaction remains opaque. Here, we show the differential response of two rice varieties (Ratna and Lalat) in terms of their morphological and biochemical changes in the presence of As and Fe. These results together with in-silico screening, gene expression analysis, and protein-protein interaction studies suggest the role of OsWRKY76 in Fe-mediated As stress alleviation. When OsWRKY76 is activated by MAPK signaling, it inhibits the gene expression of Fe transporters OsIRT1 and OsYSL2, which reduces the amount of Fe accumulated. However, MAPK signaling and OsWRKY76 remain down-regulated during Fe supplementation with As, which subsequently encourages the up-regulation of OsIRT1 and OsYSL2. This results in greater Fe content and decreased As accumulation and toxicity. The lower H2O2 and SOD, CAT, and APX activities were likewise seen under the As + Fe condition. Overall, results revealed the molecular aspects of Fe-mediated control of OsWRKY76 signaling and showed that Ratna is a more As tolerant variety than Lalat. Lalat, however, performs better in As stress due to the presence of Fe.
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    Ectopic overexpression of vacuolar and apoplastic Catharanthus roseus peroxidases confers differential tolerance to salt and dehydration stress in transgenic tobacco
    (Springer Science, 2012) Kumar, Santosh; Jaggi, Monika; Sinha, Alok Krishna
    CrPrx and CrPrx1 are class III peroxidases previously cloned and characterized from Catharanthus roseus. CrPrx is known to be apoplastic in nature, while CrPrx1 is targeted to vacuoles. In order to study their role in planta, these two peroxidases were expressed in Nicotiana tabacum. The transformed plants exhibited increased peroxidase activity. Increased oxidative stress tolerance was also observed in transgenics when treated with H(2)O(2) under strong light conditions. However, differential tolerance to salt and dehydration stress was observed during germination of T1 transgenic seeds. Under these stresses, the seed germination of CrPrx-transformed plants and wild-type plants was clearly suppressed, whereas CrPrx1 transgenic lines showed improved germination. CrPrx-transformed lines exhibited better cold tolerance than CrPrx1-transformed lines. These results indicate that vacuolar peroxidase plays an important role in salt and dehydration stress over cell wall-targeted peroxidase, while cell wall-targeted peroxidase renders cold stress tolerance.