Phenotyping and deciphering genetic resistance to yellow rust in wheat through marker-assisted analysis

Abstract

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a major threat to wheat production throughout the globe including India. This study evaluated 110 wheat genotypes for resistance to stripe rust at both the adult plant and seedling stages over two consecutive years at two locations. Adult plant resistance was assessed based on disease severity, host response, and coefficient of infection. Among the tested germplasm, 3.63 % were immune, while 6.36 % exhibited slow rusting resistance. Moderately resistant and moderately susceptible responses were observed in 29.09 % and 21.81 % of the genotypes, respectively. Principal component analysis revealed that the first component accounted for 89.50 % of the total variability in infection coefficient data. Seedling resistance was evaluated against four Pst pathotypes (46S119, 110S84, 47S103, and 110S119), showing a wide range of infection types. Five wheat lines exhibited near-immunity, while several others showed strong resistance to multiple pathotypes, suggesting the presence of effective seedling resistance genes. Molecular characterization using 54 Yr-gene-linked markers identified a high frequency of Yr5, Yr35, Yr64, Yr46, and Yr7, while Yr32, Yr18, Yr65, and Yr36 were detected at lower frequencies. The presence of Yr10, Yr15, Yr18, Yr24, Yr29, Yr36, Yr44, Yr53, and Yr65 significantly contributed to resistance. In order to improve the resistance of wheat to yellow rust, breeding programs can make use of the carriers of useful Yr genes that were identified in this study.