Publications of NIPGR Scientists

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    Promoter of CaZF, a chickpea gene that positively regulates growth and stress tolerance, is activated by an AP2-family transcription factor CAP2
    (PLOS, 2013) Jain, Deepti; Chattopadhyay, Debasis
    Plants respond to different forms of stresses by inducing transcription of a common and distinct set of genes by concerted actions of a cascade of transcription regulators. We previously reported that a gene, CaZF encoding a C2H2-zinc finger family protein from chickpea (Cicer arietinum) imparted high salinity tolerance when expressed in tobacco plants. We report here that in addition to promoting tolerance against dehydration, salinity and high temperature, the CaZF overexpressing plants exhibited similar phenotype of growth and development like the plants overexpressing CAP2, encoding an AP2-family transcription factor from chickpea. To investigate any relationship between these two genes, we performed gene expression analysis in the overexpressing plants, promoter-reporter analysis and chromatin immunoprecipitation. A number of transcripts that exhibited enhanced accumulation upon expression of CAP2 or CaZF in tobacco plants were found common. Transient expression of CAP2 in chickpea leaves resulted in increased accumulation of CaZF transcript. Gel mobility shift and transient promoter-reporter assays suggested that CAP2 activates CaZF promoter by interacting with C-repeat elements (CRTs) in CaZF promoter. Chromatin immunoprecipitation (ChIP) assay demonstrated an in vivo interaction of CAP2 protein with CaZF promoter.
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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.