Dissection of High Temperature Tolerance Mechanisms in Maize and Sorghum: A Genome-Wide Approach.

As global warming becomes inevitable, the sustainability of agricultural production in US and worldwide faces serious threat from extreme weather conditions, such as drought and elevated extreme temperatures (heat waves). High temperature (HT) and drought stresses occurred during crop growing season have caused significant losses in grain yield and grain quality worldwide. While drought stress can be relieved through irrigation where water is available, little can be done with HT stress through crop management. More importantly, damages caused by extreme HT to plant tissues and yield components in the field are mostly irreversible; and a few days of HT at pollination can result in significant yield loss.   Therefore, the only feasible way to cope with extreme HT in agriculture production is through genetic improvement of heat tolerance in crop varieties/hybrid. Evaluation of genetic variation and identification of specific traits for heat tolerance/sensitivity in crops are primary and essential steps in the study of genetic mechanisms of heat tolerance and in developing heat tolerant crops. We have taken a genetic approach to study genetic mechanisms of high temperature tolerance in maize. In this study, genetic variation among a maize germplasm panel and a sorghum mutant population were evaluated for vegetative and reproductive tissue HT tolerance traits under field condition for 3 years. Genome-wide association analyses are being performed to identify chromosome regions and/or genetic loci contributing to HT tolerance in maize and sorghum. Preliminary analysis revealed several independent traits that contribute to the variation in HT tolerance.