A Gene Encoding Cold-Circadian Rhythm-RNA Binding-Like Protein (CCR-Like) from Upland Cotton (Gossypium hirsutum L.) Confers Tolerance to Abiotic Stresses in Transgenic Tobacco

Water-deficit is the major abiotic stress factor that limits the yield and quality of cotton produced around the world. We observed earlier that a CCL (CCR-like; cold-circadian rhythm-RNA binding like) gene has been differentially expressed during boll development in cotton under drought stress in the field. Isolation and functional characterization of GhCCL from upland cotton (Gossypium hirsutum L. cv. Bikaneri Narma) was carried out in the present study. We studied the GhCCL gene structure and organization and demonstrated for the first time that GhCCL may be involved in abiotic stress tolerance response in plants. RT-PCR analysis indicated that GhCCL is differentially regulated in cotton seedlings by abiotic stresses such as salt, mannitol, cold, heat, dehydration, wounding and jasmonic acid, salicylic acid, and hydrogen peroxide. In silico and subcellular localization analysis suggested that GhCCL is localized in the chloroplasts. Constitutive expression of GhCCL in tobacco (Nicotiana tabacum var. Petit Havana) conferred tolerance to water-deficit stress and salt stresses during seed germination on amended MS media. The transgenic plants showed better growth performance and increased fresh weight under long-term stress. The transgenic plants grown in the glass house tolerated water-deficit stress (by withholding water) and recovered upon rewatering (45 days) whereas WT plants did not survive. Characterization of the GhCCL promoter sequence by in silico analysis showed various light, stress, tissue specific, and hormone responsive cis-elements. The present study suggested that GhCCL positively regulates the response to abiotic stresses, especially water-deficit stress in transgenic plants and that the overexpression of GhCCL may enhance the stability of mRNA thereby conferring tolerance to abiotic stresses.