Improved drought and salt tolerance of Arabidopsis thaliana by ectopic expression of a cotton (Gossypium hirsutum) CBF gene

Osmotic stress associated with drought or salinity is a major factor that limits plant growth and productivity. CBF transcription factors play key roles in plant stress signaling transduction pathway. In this work, the data revealed that GhCBF3 identified in cotton (Gossypium hirsutum L.) was remarkably induced by NaCl, mannitol and abscisic acid (ABA). Histochemical assay of GUS activity revealed that GhCBF3 promoter was active in stomata guard cells of the GhCBF3p:GUS transgenic seedlings, and its activity was salt- and osmotic-inducible. Overexpression of GhCBF3 in Arabidopsis resulted in the increased drought- and high salinity-tolerance, but led to an ABA-sensitive phenotype of the transgenic plants. In the presence of NaCl and mannitol, rates of seed germination and cotyledon greening of the GhCBF3 overexpression transgenic plants were higher than those of wild type. Relative water content, proline content and chlorophyll content in the GhCBF3 transgenic seedlings were higher than those in wild type. The GhCBF3 transgenic plants showed greater salt- and drought-tolerance, compared with wild type. In the presence of ABA, stomatal aperture in leaves of the transgenic plants was smaller than that in wild type, and expression levels of AREB1 and AREB2 in the transgenic leaves was remarkably higher than those in wild type. Furthermore, expression of some stress-related genes was altered in the GhCBF3 transgenic plants. These data suggested that GhCBF3 may be involved in regulating stomata closure, thereby enhance plant salt and drought tolerance via ABA signaling pathway.