Overexpression of cotton RAV1 gene in Arabidopsis confers transgenic plants high salinity and drought sensitivity.

RAV (related to ABI3/VP1) protein containing an AP2 domain in the N-terminal region and a B3 domain in the C-terminal region, which belongs to AP2 transcription factor family, is unique in higher plants. In this study, a gene (GhRAV1) encoding a RAV protein of 357 amino acids was identified in cotton (Gossypium hirsutum). Transient expression analysis of the eGFP:GhRAV1 fusion genes in tobacco (Nicotiana tabacum) epidermal cells revealed that GhRAV1 protein was localized in the cell nucleus. Quantitative RT-PCR analysis indicated that expression of GhRAV1 in cotton is induced by abscisic acid (ABA), NaCl and polyethylene glycol (PEG). Overexpression of GhRAV1 in Arabidopsis resulted in plant sensitive to ABA, NaCl and PEG. With abscisic acid (ABA) treatment, seed germination and green seedling rates of the GhRAV1 transgenic plants were remarkably lower than those of wild type. In the presence of NaCl, the seed germination and seedling growth of the GhRAV1 transgenic lines were inhibited greater than those of wild type. And chlorophyll content and maximum photochemical efficiency of the transgenic plants were significantly lower than those of wild type. Under drought stress, the GhRAV1 transgenic plants displayed more severe wilting than wild type. Furthermore, expressions of the stress-related genes were altered in the GhRAV1 transgenic Arabidopsis plants under high salinity and drought stresses. Collectively, our data suggested that GhRAV1 may be involved in response to high salinity and drought stresses through regulating expressions of the stress-related genes during cotton development.