Functional characterization of theABFgene family in upland cotton (Gossypium hirsutumL.)

The AREB/ABF bZIP transcription factors play a pivotal role in abscisic acid-dependent abiotic stress-responsive gene expression. Despite the perennial damage and reduced productivity that result from water-deficit and unpredictable early season temperature fluctuations, these critical genes have not been previously examined in upland cotton ( Gossypium hirsutum ). Here, we report the isolation of the G. hirsutum ABF homologs, characterization of their expression patterns in response to abiotic stress treatments, and examination of their functions through heterologous ectopic expression in Arabidopsis . As expected for an allotetraploid, G. hirsutum ABF homologs are present in the genome as homeologous pairs. These genes are differentially expressed, both among the homologs and within the homeologous pairs, in response to exogenous abscisic acid (ABA) application, dehydration, and chilling temperatures. Furthermore, heterologous ectopic expression of many of the G. hirsutum ABF genes in Arabidopsis conferred increased tolerance to water deficit and osmotic stress, as well as cold tolerance, in a gene specific manner. These results indicate the G. hirsutum ABF homologs are functional in Arabidopsis and, as in other species, are likely to play an essential role in the abiotic stress response. Highlight The Gossypium hirsutum ABF homeologs are differentially expressed in response to abiotic stress, and their ectopic expression in Arabidopsis can confer increased water deficit tolerance.