Institutional Publications

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Author: search.filters.author.Chattopadhyay, DebasisSubject: search.filters.subject.auxin

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    CBL-interacting protein kinase 25 contributes to root meristem development
    (Oxford University Press, 2019) Meena, Mukesh Kumar; Vishwakarma, Niraj Kumar; Tripathi, Vineeta; Chattopadhyay, Debasis
    Coordination of auxin and cytokinin activities determines root meristem size during post-embryonic development. Calcineurin B-like proteins (CBLs) and their interacting protein kinases (CIPKs) constitute signaling modules that relay calcium signals. Here we report that CIPK25 is involved in regulating the root meristem size. Arabidopsis plants lacking CIPK25 expression displayed a short root phenotype and a slower root growth rate with less meristem cells. This phenotype was rescued by restoration of CIPK25 expression. CIPK25 interacted with CBL4 and -5, and displayed a strong gene expression in the flower and root except in the cell proliferation domain in the root apical meristem. Its expression in root was positively and negatively regulated by auxin and cytokinin, respectively. cipk25 T-DNA insertion line was compromised in auxin transport and auxin-responsive promoter activity. cipk25 mutant line showed altered expression of auxin efflux carriers and an Aux/IAA family gene SHY2. Decreased PIN1 and PIN2 expression in cipk25 mutant line was completely restored when combined with SHY2 loss-of-function mutation resulting in recovery of root growth. SHY2 and PIN1 expression was partially regulated by cytokinin even in absence of CIPK25, suggesting existence of CIPK25-independent cytokinin signaling pathway(s) as well. Our results suggested a role of CIPK25 in root meristem development.
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    Role of CIPK6 in root growth and auxin transport
    (Landes Bioscience, 2009) Tripathi, Vineeta; Syed, Nazia; Laxmi, Ashverya; Chattopadhyay, Debasis
    In our recent publication,1 we have shown that a T-DNA insertion in Arabidopsis CIPK6 gene encoding a CBL-interacting protein kinase caused reduction in expression of the gene and emergence of lateral roots. The change in phenotype in the mutant line was likely due to reduction in shoot-to-root acro- petal and the root tip basipetal auxin transport. Here we report identification of a homozygous knockout line of AtCIPK6 (atcipk6) with no detectable expression of the gene in normal growth condition. The knockout line exhibited considerable decrease in growth rate of the taproot as well as in emergence of lateral roots. The mutant line also showed reduction in the root tip basipetal and shoot-to-root acropetal auxin transport. Relative rate of auxin transport and the root phenotype of the atcipk6 closely matched with those of pgp4-1, an Arabidopsis line mutated in PGP4. This gene encodes an ABC integral membrane transporter, which functions in polar auxin transport. These observations strengthen our earlier proposal that CIPK6 is probably involved in polar auxin transport and indicate that it may function through the PGP4 auxin transporter.
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    CIPK6, a CBL-interacting protein kinase is required for development and salt tolerance in plant
    (Wiley-Blackwell, 2009) Tripathi, Vineeta; Parasuraman, Boominathan; Laxmi, Ashverya; Chattopadhyay, Debasis
    Calcineurin B-like proteins (CBL) and CBL-interacting protein kinases (CIPK) mediate plant responses to a variety of external stresses. Here we report that Arabidopsis CIPK6 is also required for the growth and development of plants. Phenotype of tobacco plants ectopically expressing a homologous gene (CaCIPK6) from the leguminous plant chickpea (Cicer arietinum) indicated its functional conservation. A lesion in AtCIPK6 significantly reduced shoot-to-root and root basipetal auxin transport, and the plants exhibited developmental defects such as fused cotyledons, swollen hypocotyls and compromised lateral root formation, in conjunction with reduced expression of a number of genes involved in auxin transport and abiotic stress response. The Arabidopsis mutant was more sensitive to salt stress compared to wild-type, while overexpression of a constitutively active mutant of CaCIPK6 promoted salt tolerance in transgenic tobacco. Furthermore, tobacco seedlings expressing the constitutively active mutant of CaCIPK6 showed a developed root system, increased basipetal auxin transport and hypersensitivity to auxin. Our results provide evidence for involvement of a CIPK in auxin transport and consequently in root development, as well as in the salt-stress response, by regulating the expression of genes.