1a.Objectives (from AD-416):
Develop wheat germplasm lines with resistance or tolerance to wheat rusts, Fusarium head blight, pre-harvest sprouting, heat stress, or drought stress. Construct and analyze populations to identify genes controlling these traits. Develop improved genotypic or phenotypic selection technologies for these traits.
1b.Approach (from AD-416):
Association mapping populations have been constructed and are now being analyzed. For genotyping, we will use conventional SSRs, STS, and SNP markers and a genotyping-by-sequencing (GBS) approach suitable for the large complex genomes of wheat. Genotyping-by-sequencing uses restriction enzymes to produce a reduced representation of the genome that is then multiplex sequenced on the Illumina platform using DNA barcode adapters. We are able to identify tens of thousands of SNPs in each sample and use this information for genetic mapping and breeding. We will use the GBS data to identify SNP markers closely linked with the resistance genes while making background selection for the recurrent parent genotype. This marker assisted back-crossing approach will. 1)identify molecular markers linked to traits of interest and. 2)rapidly recover the elite wheat background for using these genes in breeding.
High temperature has been a major constraint for wheat production in the Great Plains region, and will become a more important factor due to global warming. Identifying heat tolerant lines through large scale screening of germplasm lines in precisely controlled growth chambers is the key to develop heat tolerant varieties. During the past year, we tested two association mapping panels for heat tolerance. One is a panel of 160 Asian spring wheat lines and the other is a panel of 304 winter wheat lines. Accessions were subjected to heat stress for three weeks. Lines with heat tolerance were identified based on grain yield and the “stay-green” trait whereby chlorophyll content remains high under heat stress treatments. Eight tolerant lines and 3 very susceptible lines based on the stay-green trait have been selected. They are currently being grown at high temperatures in growth chambers to confirm the results. Tolerant and intolerant lines will be intercrossed to develop new mapping populations to identify the genes that control heat tolerance in these lines. Genotyping data is being collected so that these two panels can be subjected to association analysis to identify additional genes that control heat tolerance.