CULTIVAR DEVELOPMENT: ACCELERATED INTROGRESSION OF SYNTHETIC HEXAPLOID DERIVED DIVERSITY INTO AN APPLIED HARD WINTER WHEAT BREEDING PROGRAM

Understanding plant responses to environmental stresses is critical for choosing crop plant varieties that mitigate the impact of biotic and abiotic constraints on food production. Little is known about the complex shifts in secondary metabolic pathways for plant protection from environmental stresses. We are exploring the cytochrome P450 enzyme subfamily, CYP72As, as candidates for shifting metabolic flux from growth-related products to metabolites needed for protection. In some plants, CYP72A enzymes detoxify herbicides, so they may naturally play a role in breaking down unwanted metabolites that accumulate under stress. Maize is an important global food plant that is subject to multiple combinations of environmental stresses. We have found that the absence of two CYP72A genes in maize makes salt stressed plants less susceptible to attack by caterpillars. Therefore, this project will test the hypothesis that CYP72A enzymes are involved in abiotic stress responses that compete with biotic stress defenses. Using molecular genetic techniques, metabolic profiling, and computational studies, this project will:1) isolate additional CYP72A mutations and alter expression levels with virus constructs;2) measure abiotic and biotic stress responses associated the CYP72A mutations; and3) determine the chemical nature of metabolites produced by CYP72As.These objectives will uncover complexities in maize acclimation to abiotic stress that apply to other crops species, such as sorghum and millet. This work addresses the Physiology of Agricultural Plants Program Area Priority to support projects on the mechanisms of plant response to abiotic stress as well as projects on secondary metabolism in agriculturally important plants.