Identification of heat responsive genes in cotton

High summer temperature negatively affects cotton yield, and better understanding of genetic mechanisms of heat stress responses in cotton may facilitate development of new heat tolerant cultivars. We attempted to determine heat responsive genes in cotton using tolerant (Stoneville 453, BA 119) and susceptible (Nazilli 84S) cultivars. Twenty five expressed sequence tags (ESTs) were sequenced and studied for gene homology. Sixteen ESTs were significantly similar to known genes, whereas eight ESTs were similar to not annotated cDNA clones and 1 EST did not show homology to any known gene. Expression of some ESTs was analyzed by quantitative real-time PCR and IAA-ala hydrolase (IAR3), folylpolyglutamate synthase (FPGS3), and two not annotated ESTs (GhHS126 and GhHS128) were consistently up-regulated under both short- and long-term heat stress. Since cotton is considered relatively more heat tolerant than most of the other crops, it can be suggested that these genes and ESTs could play a significant role in heat tolerance. In addition, GhHS126 and GhHS128 might be parts of the new candidate genes for heat tolerance.