Expression Profile of Early Responsive Genes Under Salt Stress in Upland Cotton (Gossypium hirsutum L.)

Cotton (Gossypium spp.) is an important fiber and oil crop. High soil salinity affects cotton growth and production severely. To identify genes in response to salt stress and clarify salt tolerance mechanism in cotton, suppression subtractive hybridization (SSH) libraries were constructed from cotton roots under salt stress. A total of 1,131 expressed sequence tags (ESTs) from both forward and reverse libraries were assembled into 468 uniESTs and grouped into 11 functional categories according to Gene Ontology prediction. The results showed that many physiological processes of cotton were influenced by salt stress. Some signaling elements and transcription factors, which might play important roles in salt stress response, were carefully discussed. The expression patterns of 21 selected genes under salt stress were validated by parallel method semi-quantitative reverse transcriptase-polymerase chain reaction (semi-quantitative RT-PCR), which were consistent with SSH results. An interaction network of salt-responsive genes was constructed and three molecular regulatory pathways of cotton were deduced. Our findings might result in further understanding of salt stress response in cotton and contribute to genetically modified cotton with enhanced salt tolerance.