Email: m.zaim@cgiar.org

Durum wheat is mostly cultivated under rainfed conditions in the Mediterranean Basin, where the precipitation is irregular across years and locations resulting often to moisture stress. Therefore, the identification of loci controlling the capacity of genotypes to convert moisture into grain yield is quintessential to stabilize production despite climatic variations.

In a first study, four recombinant inbred lines (RIL) populations were used to conduct quantitative trait loci (QTL) discovery for grain yield (GY). A total of 576 individuals were sown at three locations in Morocco and Lebanon. These individuals were genotyped by sequencing with 3,202 high-confidence polymorphic markers, to derive a highly dense consensus genetic map. Six QTLs were found to be associated with GY and independent from flowering time, explaining high phenotypic variation. To confirm our findings, a global panel of 384 accessions was tested across eighteen environments in Morocco, Lebanon, and Jordan representing a vast range of moisture levels. The accessions were assigned to water responsiveness classes.

Genome wide association studies (GWAS) revealed that six loci explained the majority of variation, among them one QTL previously found in the RIL populations. A second validation panel tested under moisture stress confirmed that carrying the positive allele at three loci generated a high average water productivity gain. These loci were tagged by Kompetitive Allele Specific PCR (KASP) markers, and these were used to screen a third independent validation panel composed by elites tested across moisture stressed sites.

These loci are now ready for molecular pyramiding and transfer across cultivars to improve the moisture conversion of durum wheat. Additionally, the material was tested for resistance to various disease, including leaf and yellow rust and tan spot. Interestingly, the results showed promising levels of resistance.