Bulked segregant analysis to identify SSR markers for loose smut resistance in bread wheat

Abstract EN

The present study was conducted to evaluate 100 F₈ recombinant inbred lines (RILs) derived from a cross between resistant and susceptible bread wheat landraces for loose smut caused by Ustilago tritici.

Bulked segregant analysis (BSA) was also used to identify simple sequence repeats (SSR) markers associated with the resistance to loose smut.

The artificial inoculation was repeated twice through two successive seasons (2017/2018 and 2018/2019) under greenhouse conditions, and responses of tested genotypes against loose smut were evaluated in 2018/2019 and 2019/2020 seasons.

Highly significant differences (P<0.01) were observed for loose smut incidence among the tested RILs, indicating a considerable genetic variation.

On average, loose smut incidence (LSI % ) of the tested RILs ranged from 0% in RIL-64 to 97.5% in RIL-74 and RIL-93, with an average of 47.5% .

Out of 100 RILs, the RIL-64 was considered as an immune genotype (no symptoms were observed on any plant), RIL-13, RIL-16, RIL-27 and RIL-37 were highly resistant (LSI= 5.0, 5.0, 2.5, 2.5% , respectively), and RIL-2, RIL-50 and RIL-96 were resistant to loose smut (LSI= 7.5, 7.5 and 10.0% , respectively), suggesting the usefulness of these genotypes for developing wheat varieties resistant to loose smut.

BSA with forty two SSRs markers identified five positive alleles generated by Xgwm18-1B, Xgwm95-2A, Xgwm294-2A, Xgwm186-5A and Xgwm293-5A markers that were associated with loose smut resistance in the tested population, suggesting that several loci could be contributed to loose smut resistance in wheat.

However further studies are still required to confirm usefulness of these markers in breeding programs.