Mining of the Global Wheat Genetic Resources

Wheat improvement has increased genetic homogeneity in the global wheat germplasm during past few decades. A broadening of the genetic base, therefore, is likely to contribute to accelerating the genetic progress in breeding programs. Efforts are underway at CIMMYT to systematically mine wheat genetic resources through Seeds of Discovery (SeeD) project, which is largely funded by the Mexican Government as part of its “MasAgro” initiative. The overall aim of SeeD is to characterize and mobilize novel, useful genetic variation from landraces, wild relatives and other underutilized sources into adapted elite genotypes. We are genome-profiling approximately 120,000 gene-bank accessions and evaluating subsets for a range of phenotypic traits under field conditions, to develop core sets and to identify marker trait associations. We primarily use genotyping-by-sequencing (GBS), but also characterize selected gene-based markers for accession subsets. In order to mobilize novel genetic variation into elite genetic backgrounds, we are developing a “linked top-cross panel” (LTP) by crossing ~200 exotic accessions to various combinations of ~10 elite lines. SeeD outputs include (i) a global “molecular wheat atlas”; (ii) donor lines harboring useful variation for stress tolerance and yield potential, and (iii) the testing and validation of new pre-breeding approaches. To this date, we have completed the phenotyping of ~70,000 accessions for heat/drought tolerance and the genome-profiling of ~40,000 accessions. A wheat reference genetic map with ~20,000 GBS markers is developed. A core set of Mexican and Iranian wheat landraces is developed. Efforts are underway for mining favorable alleles and trait specific donor accessions.