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Author: search.filters.author.Tripathi, VineetaSubject: search.filters.subject.chickpea

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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.
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    CAP2 enhances germination of transgenic tobacco seeds at high temperature and promotes heat stress tolerance in yeast
    (Wiley-Blackwell, 2009) Shukla, Rakesh Kumar; Tripathi, Vineeta; Jain, Deepti; Yadav, Rajiv Kumar; Chattopadhyay, Debasis
    We reported earlier that ectopic expression of CAP2, a single AP2 domain containing transcription activator from chickpea (Cicer arietinum) in tobacco improves growth and development, and tolerance to dehydration and salt stress, of the transgenic plants. Here, we report that, in addition, the CAP2-transgenic tobacco seeds also exhibit higher germination efficiency at high temperature and show higher expression levels of genes for tobacco heat shock proteins and a heat shock factor. CAP2 was able to activate the 5¢-upstream activating sequence of tobacco heat shock factor. Surprisingly, expression of CAP2 cDNA in Saccharomyces cerevisiae also enhanced heat tolerance, with increased expression of the gene for yeast heat shock factor 1 (Hsf1) and its target, the gene for yeast heat shock protein 104 (Hsp104). Sequence analysis of the Hsf1 promoter revealed the presence of a dehydration-responsive element ⁄ C-repeat-like element (DRE/ CRE). Recombinant CAP2 protein bound to the DRE/CRE in the Hsf1 promoter in a gel shift assay and transactivated the Hsf1 promoter–His reporter construct. The full-length CAP2 protein was required to provide thermotolerance in yeast. If these findings are taken together, our results suggest that CAP2 is involved in the heat stress response and provides an example of functioning of a plant transcription factor in yeast, highlighting the strong evolutionary conservation of the stress response mechanism.
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    Expression of CAP2, an AP2-family transcription factor from chickpea enhances growth and tolerance to dehydration and salt tress in transgenic tobacco
    (American Society of Plant Biologists, 2006) Shukla, Rakesh K.; Raha, Sumita; Tripathi, Vineeta; Chattopadhyay, Debasis
    The APETALA2 (AP2) domain defines a large family of DNA-binding proteins that play important roles in plant morphology, development, and stress response. We describe isolation and characterization of a gene (CAP2) from chickpea (Cicer arietinum) encoding a novel AP2-family transcription factor. Recombinant CAP2 protein bound specifically to C-repeat/dehydration- responsive element in gel-shift assay and transactivated reporter genes in yeast (Saccharomyces cerevisiae) one-hybrid assay. CAP2 appeared to be a single/low copy intronless gene, and the protein product localized in the nucleus. Transcript level of CAP2 increased by dehydration and by treatment with sodium chloride, abscisic acid, and auxin, but not by treatment with low temperature, salicylic acid, and jasmonic acid. The 35S promoter-driven expression of CAP2 in tobacco (Nicotiana tabacum) caused drastic increase in the leaf cell size, and, thereby, in leaf surface area and number of lateral roots. Transgenic plants demonstrated more tolerance to dehydration and salt stress than the wild-type plants. Transgenic plants expressed higher steady-state transcript levels of abiotic stress-response genes NtERD10B and NtERD10C and auxin-response genes IAA4.2 and IAA2.5. Taken together, our results indicated a mutual interrelation between plant growth-development and abiotic stress- response pathways and a probable involvement of CAP2 in both the signaling pathways.