Wheat-related wild species have been recognized as an important genetic resource for wheat improvement, and many accessions are maintained in genebanks. Useful qualitative genes, such as disease resistance, have been found in these wild species and used in breeding programs. However, there is insufficient evidence that these exotic germplasm can provide useful quantitative traits such as yield performance and abiotic stress tolerance.

The morphology of wild species, with small seeds in hard and brittle spikelets, is so different from that of cultivated wheat. Thus, it may be difficult to evaluate the "agronomic traits" of the wild species. Therefore, instead of evaluating the wild species themselves, we adopted a strategy of first developing a highly diverse wheat population by introducing various alleles from many accessions of wild species, and then evaluating the agronomic traits by the wild alleles in the wheat genetic background.

We used 43 primary synthetic hexaploid wheat (SHW) lines with common A and B genomes and D genomes from 43 Aegilops tauschii accessions covering its intraspecific diversity. We crossed and backcrossed the SHWs with a Japanese commercial cultivar "Norin 61" (N61), mixed the BC1F2 seeds and self-pollinated for several generations to fix the alleles. We named this diverse population in the N61 genetic background “multiple synthetic derivative (MSD) population”. We then selected 400 genotypes from the MSD population and genotyped each plant with genome-wide molecular markers, which was named "MSD Panel".

Field evaluation of the MSD population for heat and drought tolerance in Sudan, followed by GWAS, revealed a number of molecular markers for traits associated with tolerance to both stresses. Our intensive and systematic phenotypic and genotypic studies clearly indicated that wild species harbor positive alleles to improve stress tolerant quantitative traits. However, the direct use of such alleles in breeding programs remains challenging, unless the additive and epistatic effects of these alleles have been validated.

Therefore, using molecular markers for the stress-adaptive traits, we are producing near-isogenic lines (NILs) using MSD lines with favorable alleles as donor parents and N61 or other elite cultivars as recurrent parents.