Genetic Mapping and Physiological Breeding Towards Heat and Drought Tolerance in Wheat

Wheat represents about 30% of the world cereal area, with 220 million ha cultivated worldwide, often under abiotic stress. Despite advances in understanding the genetic basis of flowering time and disease resistance, the genetic basis of heat and drought tolerance is poorly understood. At present in the CIMMYT physiology group, we have developed and tested several physiological traits related to heat and drought stress that can be used for gene discovery and physiological breeding. Conceptual models for heat and drought stress tolerance to genetically improve wheat through physiological traits were proposed earlier. In this talk, we will focus on the genetic mapping of physiological traits associated with heat and drought tolerance. Heat stress tolerance was measured using spectral indices to detect photo protective molecules, membrane thermostability and stay green traits. Genome-wide association mapping was done on a Wheat Association Mapping Initiative (WAMI) panel for these traits. Also a complementary bi-parental approach was followed on a phenology controlled population—Synthetic × Weebil— to study heat, drought, and heat+ drought tolerance. These populations were genotyped through 90K SNP markers. In addition, advances in genetic gains from physiological trait (PT) crosses based breeding for heat and drought tolerance will be discussed based on the data from international nurseries of CIMMYT.