Genetics and identification of molecular markers linked to resistance to loose smut (Ustilago tritici) race T33 in durum wheat

This study was conducted to determine the genetic control of resistance to loose smut caused by Ustilago tritici race T33 in two durum recombinant inbred line populations (DT662 x D93213 and Sceptre x P9162-BJ08*B) and to identify molecular markers linked to the resistance. Resistance in both populations was controlled by single genes. Two SSR markers were linked with loose smut resistance in the Sceptre x P9162-BJ08*B population. In DT662 x D93213, two AFLP, two wheat SSRs and one SCAR markers were linked to resistance. The SCAR marker, 3.2 cM distal to the smut resistance locus (Utd1) on chromosome 5BS, accounted for up to 64% of the variability in disease reaction; the other markers were proximal to Utd1 at genetic distances ranging from 5.9 to 35.9 cM. SSR markers Xgwm234 and Xgwm443 segregated in both crosses suggesting a common resistance gene. The SCAR and SSR markers can be used effectively for marker assisted selection to incorporate loose smut resistance into durum cultivars.