91桃色

Abstract

Gossypium arboreum is considered to be a rich source of stress responsive genes and EST data base revealed that mostly of its genes are uncharacterized. The full length Gossypium universal stress protein-2 (GUSP-2) gene (510bp) was cloned in E.coli, Pichia pastoris and Gossypium hirsutum, characterized and point mutated at three positions separately at 352-354, Lysine-60 to proline (M1-usp-2) and 214-216, aspartic acid-26 to serine (M2-usp-2) & 145-147, Lysine-3 to proline (M3-usp-2) to study its role in abiotic stress tolerance. It was found that heterologus expression of one mutant (M1-usp-2) provided enhanced tolerance against salt and osmotic stresses, recombinant cells have higher growth up to 10-5dilution in spot assay as compared to W-usp-2 (wild type GUSP-2), M2-usp-2 and M3-usp-2 genes. M1-usp-2 in Pichia pastoris transcript profiling exhibited significant expression (7.1-fold) to salt and (9.7) and osmotic stresses. M1-usp-2 gene was also found to enhance drought tolerance and significant expression (8.7) in CIM-496-Gossypium hirsutum transgenic plants. However, little tolerance against heat and cold stresses both in recombinant yeast and bacterial cells was observed. The results from our study concluded that activity of GUSP-2 was enhanced in M1-usp-2 but wipe out in M2-usp-2 and M3-usp-2 response remained almost parallel to W-usp-2. Further, it was predicted through in silico analysis that M1-usp-2, W-usp-2 and M3-usp-2 may be directly involved in stress tolerance or function as signaling molecule to activate the stress adaptive mechanism

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