Institutional Publications

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Author: search.filters.author.Sinha, Alok KrishnaSubject: search.filters.subject.ABA

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    MPK3 mediated phosphorylation inhibits the dimerization of ABI5 to fine-tune the ABA signaling in Arabidopsis
    (Elsevier B.V., 2025) Bhagat, Prakash Kumar; Verma, Neetu; Pandey, Shubhangi; Verma, Deepanjali; Sinha, Alok Krishna
    Seed germination is, a critical physiological process, is tightly regulated by the phytohormone abscisic acid (ABA). However, the cross talk between multiple regulatory pathways involved in seed germination remains poorly understood. Here, we show that ABA activates two MAP kinases, AtMPK3/AtMPK6, which interact with and phosphorylate AtABI5, a master regulator of ABA signaling. MAP kinase-mediated AtABI5 phosphorylation at the serine-314 position regulates its nuclear localization and dimerization. Interestingly, AtABI5 provides feedback regulation by directly binding to the promoter of AtMPK3 to modulate its transcription. Further, functional analyses revealed that overexpression of a phospho-null AtABI5S314A variant in the abi5-8 mutant background conferred increased ABA sensitivity during seed germination, heightened drought sensitivity, and delayed flowering compared to wild-type plants. Conversely, overexpression of phospho-mimic AtABI5S314D in abi5-8 mutant showed ABA insensitivity during seed germination, drought tolerance, and early floral transition similar to abi5-8 mutant. Collectively, our findings highlight that MAP kinase-mediated phosphorylation of AtABI5 fine-tunes ABA signaling by regulating its dimerization, providing new insights into the dynamic regulation of plant responses to environmental and developmental cues.
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    MKK3-MPK6-MYC2 module positively regulates ABA biosynthesis and signalling in Arabidopsis
    (Springer Nature Publishing AG, 2020) Verma, Deepanjali; Bhagat, Prakash Kumar; Sinha, Alok Krishna
    Involvement of MAPK cascades is well studied in the regulation of ABA mediated responses such as stomatal opening, seed germination and stress tolerance. However most of the studies have focused on ABA signalling and involvement of MAPKs in ABA biosynthesis remains elusive. Hence, in the current study, we have identified the new role of MKK3- MPK6-MYC2 module in positive regulation of ABA biosynthesis as well as ABA responsive genes. Seed germination studies disclosed the ABA insensitive phenotype of myc2, mpk6 and mkk3 mutants. Reduced expression of ABA biosynthesis genes, ABA2 and NCED3 in myc2 and MAPK cascade mutants was confirmed by witnessing the direct binding of MYC2 to the promoter of ABA2 in EMSA assays. Additionally, ABA responsive genes also displayed altered expression patterns in these mutants. Further, transcript and biochemical studies validated the role of MPK6 upstream to MYC2 and downstream to MKK3 in response to ABA. Altogether, we have shown that MKK3-MPK6-MYC2 module induces the expression of several ABA related genes and regulate ABA mediated inhibition of seed germination.
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    Stress induced beta subunit of heterotrimeric G-proteins from Pisum sativum interacts with mitogen activated protein kinase
    (Landes Bioscience, 2011) Bhardwaj, Deepak; Sheikh, Arsheed Hussain; Sinha, Alok Krishna; Tuteja, Narendra
    We here report in Pisum sativum system a novel protein-protein interaction of β-subunit of heterotrimeric G-proteins (PsGβ) with a Mitogen activated protein kinase (PsMPK3) during cDNA library screening by yeast-two-hybrid assay. The transcript of these two genes also showed co-regulation under abscisic acid (ABA) and methyl jasmonate (MeJA) treatments. The protein-protein interaction was further validated by performing one-to-one interaction and β-galactosidase assay in yeast system. β-subunit of G-proteins from a heterologous system Oryzae sativa also showed interaction with PsMPK3. The interaction between PsGβ and PsMPK3 was further confirmed by in vitro protein-protein interaction. This suggested that MPK3 function as effector molecule for Gβ, which may helps in the regulation of stomatal functioning. These findings also provide an evidence for a possible cross-talk between MPK3 and G-protein-mediated signaling pathways in plants.