Correlation Analysis of some SSR Markers with Brown Rust Resistance Indices in Some Bread Wheat Cultivars

Leaf rust of wheat caused by Puccini recondite tritici is one of the most important diseases of wheat in the world. It is important to know the resistance genes and genotypes for wheat breeders. This study was performed to investigate the genetic variation of resistance to brown rust disease and to analyze the association of resistance indices in bread wheat using SSR molecular markers. In this study, 32 bread wheat cultivars were planted in a randomized complete block design with three replications in 1965-1959 at the Iraqi Research Station in Gorgan. Genotypes were evaluated for traits such as infection type, percentage of infection and area under disease progression curve. Communication analysis was performed using two steps of stepwise regression and single marker based on completely unbalanced randomized design. Results of analysis of variance showed that genotypes were significantly different at 1% probability level for the studied traits. The highest positive correlation coefficient was observed between the type of infection and the percentage of infection and then between the percentage of infection and the area under the curve of disease progression. Stepwise regression results showed that in total nine SSR markers were significantly associated with at least one of the three traits studied. Coefficients of explanation for SSR markers varied from 24.1% (severity of infection) to 95.9% (infection type). Xgwm344 marker in the infection type and infection percentage with 62% and 58.3% and Xgwm547 marker in the infection type with 51.6% had the highest coefficient of explanation as group marker. Results of single marker method showed that markers Xgwm146, Xgwm344, Xgwm547, Xwmc317, Xcfa2257 and Xbarc159 with all three traits and Xgwm582 marker with two traits of infection type and percentage of contamination. According to the results of both methods, five markers Xgwm146, Xgwm344, Xgwm547, Xwmc317 and Xbarc159 showed correlation with all three traits and Xbarc8 marker did not show any association with any of the traits.