Transcriptional responses of allotetraploid cotton species to salt stress

Five allotetraploid cotton species have adapted, through their transcriptional responses, to unique environments with distinct levels of inherent abiotic stresses. The transcriptional responses of leaf and root tissue in five allotetraploid cotton species (Gossypium hirsutum, G. barbadense, G. tomentosum, G. mustelinum, and G. darwinii) under salt stress have been investigated in this study using cotton long oligonucleotide microarrays. Physiological responses to salinity such as stomatal conductance, ion and osmoprotectant contents were also measured as indicators of imposed stress. Accessions from these five cotton species were hydroponically grown and gradually introduced to a NaCl treatment (15 dS m-1). The microarray results identified 2721 and 2460 differentially expressed genes under salt stress that were significant in leaf and root tissue, respectively. Many of these genes were classified under gene ontology (GO) categories that suggest abiotic stress. These allotetraploid cottons shared transcriptional responses to salinity, but also showed responses that were species-specific. No consistent differences in transcriptional response among the previously estimated phylogenetic branches were found. Stomatal conductance, ion accumulation, and betaine, trigonelline, and trehalose contents also indicated salt stress. This global assessment of transcriptional and physiological responses to salt stress of these cotton species may identify possible gene targets for crop improvement and evolutionary studies of cotton. Keywords: CEGC Cotton oligo salt stress The transcriptional responses of leaf and root tissue in five allotetraploid cotton species (Gossypium hirsutum, G. barbadense, G. tomentosum, G. mustelinum, and G. darwinii) under salt stress have been investigated in this study using cotton long oligonucleotide microarrays. Physiological responses to salinity such as stomatal conductance, ion and osmoprotectant contents were also measured as indicators of imposed stress. Accessions from these five cotton species were hydroponically grown and gradually introduced to a NaCl treatment (15 dS m-1).