Abstract
A potent cold and drought regulatory protein-encoding gene (CcCDR) was isolated from the subtractive cDNA library of pigeonpea plants subjected to drought stress. CcCDR was induced by different abiotic stress conditions in pigeonpea. Overexpression of CcCDR in Arabidopsis thaliana imparted enhanced tolerance against major abiotic stresses, namely drought, salinity, and low temperature, as evidenced by increased biomass, root length, and chlorophyll content. Transgenic plants also showed increased levels of antioxidant enzymes, proline, and reducing sugars under stress conditions. Furthermore, CcCDR-transgenic plants showed enhanced relative water content, osmotic potential, and cell membrane stability, as well as hypersensitivity to abscisic acid (ABA) as compared with control plants. Localization studies confirmed that CcCDR could enter the nucleus, as revealed by intense fluorescence, indicating its possible interaction with various nuclear proteins. Microarray analysis revealed that 1780 genes were up-regulated in CcCDR-transgenics compared with wild-type plants. Real-time PCR analysis on selected stress-responsive genes, involved in ABA-dependent and -independent signalling networks, revealed higher expression levels in transgenic plants, suggesting that CcCDR acts upstream of these genes. The overall results demonstrate the explicit role of CcCDR in conferring multiple abiotic stress tolerance at the whole-plant level. The multifunctional CcCDR seems promising as a prime candidate gene for enhancing abiotic stress tolerance in diverse plants.
Highlights
Abiotic stress conditions such as drought, salinity, and extreme temperatures cause adverse effects on the overall growth and yield potential of diverse crop plants
A potent cold and drought regulatory protein-encoding gene (CcCDR) was isolated from the subtractive cDNA library of pigeonpea plants subjected to drought stress
GD173778) of 200 bp was obtained from the cDNA library of pigeonpea plants subjected to 20% polyethylene glycol (PEG) stress (–1.01 ± 0.02Mpa)
Summary
Abiotic stress conditions such as drought, salinity, and extreme temperatures cause adverse effects on the overall growth and yield potential of diverse crop plants. Perception of stress signal(s) and activation of complex signalling pathway(s) bring about drastic changes in the cellular gene expression which is a prequisite for plants to acclimatize under extreme conditions (Kasuga et al, 1999; Tong et al, 2007). Drought, and cold stresses are different in nature, they are, known to activate certain sets of common genes in plants. The second group includes signalling molecules, transcription factors, and protein kinases (Shinozaki and Yamaguchi-Shinozaki, 1997). Products of these genes participate in the generation of regulatory molecules such as plant hormones, namely abscisic acid (ABA), ethylene, and salicylic acid (SA) (Xiong et al, 2002).
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