Unveiling loose smut resistance in Indian bread wheat germplasm: Gene postulation and pedigree analysis

Abstract

The present study is aimed at the postulation of Ut genes in loose smut-resistant bread wheat (Triticum aestivum L.) genotypes and establishing a correlation with their pedigree. Loose smut caused by Ustilago segetum tritici (Ust) is an internal seed-borne disease of wheat that can be managed through chemical seed treatment. However, due to the absence of evident symptoms, seed treatment is not a regular practice in the farming community. Thus, the use of resistant cultivars is an efficient and sustainable approach for the management of loose smut of wheat. The majority of current wheat cultivars are susceptible to loose smut. Therefore, there is a pressing need for the development of resistant cultivars, which requires the identification of resistant donors with known resistant genes. In this study, field screening for 3 years resulted in the identification of 124 bread wheat genotypes conferring stable resistance against Ust race T11. Molecular marker-based identification of Ut genes (Ut4–Ut11) revealed the presence of these genes either singly or in combination in 118 genotypes. Among them, six genotypes showed different combinations of five Ut genes, namely, WH 1218 and HI 1633 (Ut4, Ut6, Ut8, Ut9, Ut11), HD 3377 (Ut4, Ut6, Ut8, Ut9, Ut10), WH 1218 and HI 1633 (Ut4, Ut6, Ut9, Ut10, Ut11), and HD 3226 (Ut4, Ut5, Ut6, Ut9, Ut11). The genotypes with multiple genes for loose smut resistance can be used as donors for transferring the resistance into the high-yielding cultivars. Furthermore, the pedigree of each genotype was analyzed to find the gene source of the postulated Ut genes. None of the genotypes showed consistent association with the gene source of the postulated Ut gene present in the pedigree. Thus, no association between molecular marker-based postulation and pedigree of genotypes was inferred. However, the root pedigree of common parents revealed five putative sources of loose smut resistance, that is, Chris, Thatcher, Federation, New-Thatch, and Ostka-Galicyjska, in most of the genotypes under evaluation in the present study.