2010 Annual Report 1a.Objectives (from AD-416) Freezing injury is a major source of risk and yield loss in winter wheat (Triticum aestivum L. em Thell) production. Our long-term goal is to improve frost tolerance in cultivated wheat. 1b.Approach (from AD-416) We will use known CBF gene sequences and ESTs to identify and sequence the orthologous CBF genes on wheat chromosomes 5A, 5B and 5D. The primers developed will be used to resequence TaCBF-12, TaCBF-14 and TaCBF-15. BC2F2 populations will be developed and we will determine the effect of each Fr-2 haplotype on frost tolerance in BC2F2 sister lines. We will use the BC2F2 sister lines for the different Fr-2 haplotypes and TILLING knockout mutants to determine the LT-TIT of CBF and COR genes. We will then produce CBF12, CBF14 and CBF15 knock-out mutants on both the A and B genomes using our tetraploid TILLING population in the durum wheat cultivar Kronos. Yr 1: $120,548; Yr 2: $127,374; Yr 3: $101,743.Documents Reimbursable with NRI-CGP CSREES. Log 37534. 3.Progress Report The question is whether sequence diversity detected for cold response genes of wheat will be correlated to differences in low temperature threshold induction temperatures and/or frost tolerance. The methods used are to compile a diverse set of winter wheat, assay this collection for frost tolerance, low temperature threshold induction temperature and other traits associated with response to cold, as well as sequence diversity for the CBF12, CBF14, and CBF15 genes. To date we have detected a wide range in frost tolerance amoung this panel of genotypes and detected polymorphisms for the CBF12 loci in a subset of these genotypes. This research will result in breeding populations and molecular marker tools that can be used to select for improved winter survival in wheat.