1a. Objectives (from AD-416):
Agronomically important genes for wheat will be identified and deployed using a genetic approach in wheat and Arabidopsis. The genetic mechanisms by which the plant hormones abscisic acid (ABA) and gibberellin (GA) control pre-harvest sprouting, stand establishment, and drought and cold tolerance in wheat and Arabidopsis. Spring and winter wheat cultivars with durable resistance to stripe rust, soilborne disease, cold and drought, and improved end-use quality will be developed.
1b. Approach (from AD-416):
Multiple approaches will be employed. The genetic diversity of wheat plants will be increased using wide crosses to wheat relatives and thorough mutagenesis and selection of new traits. We will determine whether ABA sensitivity controls grain dormancy and tolerance to preharvest sprouting using wheat mutants with increased and decreased sensitivity to ABA. The degree to which preharvest sprouting, drought tolerance and cold tolerance depends upon ABA sensitivity will be determined using association mapping, and wheat mutants with increased and decreased ABA sensitivity. The mechanisms by which GA signaling controls seed dormancy and plant height using Arabidopsis as a model system to determine exactly how GA response genes control gene expression during seed germination. New sources of genes giving superior end-use quality, disease resistance, and resistance to cold and drought conditions will be identified through characterization of material from the USDA-ARS National Small Grains Germplasm Collection. New approaches for deployment of these genes through the identification of new molecular markers, use of molecular markers to score segregation in breeding lines, employment of Bayesian statistics, and classical statistical plant breeding.
3. Progress Report:
It is important to understand the mechanisms controlling wheat drought and cold tolerance. Too little cold tolerance leads to yield loss due to winter kill of winter wheat, whereas insufficient drought tolerance leads to yield loss and poor grain filling in semi-arid regions of Washington state. ARS Research Scientist and Washington State University post-doctoral fellow identified alleles of the cold tolerance genes called CBF (CRT binding factor) associated with sensitivity or resistance to sub-freezing temperatures. ARS Research Scientist and Washington State University post-doctoral and graduate student found that the ABA hypersensitive mutant Warm4 results in reduced water loss in responses to the hormone ABA and in increased water use efficiency. The progress of post-doctoral fellows and of the graduate student were monitored through weekly laboratory meetings, weekly individual meetings, and monthly progress reports. This project supports parent project 5348-21000-023-00D Objective 1, Sub-objective B.