Cloning and functional characterization of moisture stress responsive transcription factors from finger millet(Eleusine coracana(L) Gaertn)
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Date
2009-04-29
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University of Agricultural Sciences, Bengaluru
Abstract
Abiotic stress tolerance is a multigenic trait and genetic manipulation to improve stress
tolerance in model system has no doubt provided leads in identifying the relevant
mechanisms and also genes, especially upstream regulatory genes, regulating this trait.
Since the threshold for tolerance differs amongst the species, identification and functional
characterization of genes from stress adapted crop species forms an important theme of
crop abiotic stress functional genomics. Further, the emphasis has been on signaling
pathways, in particular transcription factors (TFs) that trigger protective genes bringing
about not only enhanced plant survival per se but also improving crop productivity under
stressful environment.
The present study involves identification and functional characterization of stressresponsive
TFs from stress adapted species finger millet. Initially, gradual drought stress
was imposed by gravimetric method simulating field situation and drought stress specific
cDNA library was constructed from the leaf tissue. Following genome synteny as an
approach six TFs, belonging to MYC, bZIP (GBF1 and GBF3), NAC and Zn-finger (two)
TF super-family, have been identified by plaque hybridization using diverse stress
responsive rice TF genes as probes. The stress responsive nature of these TFs has been
revalidated by semi-quantitative and quantitative real-time RT-PCR analysis. Adapting
RNAi based reverse-genetic approach, the functional relevance of NAC and MYC genes
in stress tolerance was demonstrated in model system tobacco. Further, full-length cDNA
clones of NAC and GBF1 were derived from finger millet and expressed under
constitutive or stress-inducible promoter in tobacco. The functional significance of
EcNAC1 gene was demonstrated using various abiotic stress screens and a few possible
NAC target genes were studied by semi-quantitative RT-PCR analysis. The results from
empirical screening of T1 transgenic plants under various abiotic stresses and also the
induced expression of probable target genes of NAC provide strong in vivo evidence that
EcNAC1 plays positive role in stress adaptation.
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Keywords
planting, genes, transcription, transgenics, transcription factors, tolerance, proteins, weather hazards, enzymes, aba