Transcriptome profilling analysis characterized the gene expression patterns responded to combined drought and heat stresses in soybean.

Heat and drought are the two major abiotic stress limiting soybean growth and output worldwide. Knowledge of the molecular mechanisms underlying the responses to heat, drought, and combined stress is essential for soybean molecular breeding. In this study, RNA-sequencing was used to determine the transcriptional responses of soybean to heat, drought and combined stress. RNA-sequencing analysis demonstrated that many genes involved in the defense response, photosynthesis, metabolic process, etc. are differentially expressed in response to drought and heat. However, 1468 and 1220 up-regulated and 1146 and 686 down-regulated genes were confirmed as overlapping differentially expressed genes at 8 h and 24 h after treatment, and these genes are mainly involved in transport, binding and defense response. Furthermore, we compared the heat, drought and the combined stress-responsive genes and identified potential new targets for enhancing stress tolerance of soybean. Comparison of single and combined stress suggests the combined stress did not result in a simple additive response, and that there may be a synergistic response to the combination of drought and heat in soybean.