Inheritance of resistance to stripe rust in three lines of soft red winter wheat
Since 2000, stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks., has been the most important foliar disease of wheat in the eastern United States. Three lines of soft red winter wheat, ‘McCormick’, VA96W-270, and a variant of VA96W-270 (VA96W-270V), were resistant to the stripe rust population first described in the United States in 2000. The objective of this study was to characterize the inheritance of this resistance. Each line was crossed to the susceptible cultivar Coker 9835. Parental and F1 plants were characterized for reaction to races PST-3 and PST-100 of P. striiformis f. sp. tritici in growth chamber experiments. Parents and F1, F2, F3, F4, and BC1F1 progenies were evaluated for reaction to race PST-100 over 3 yr in inoculated field experiments. Stripe rust resistance was conferred by two to three recessive, race-specific adult-plant genes in McCormick, and by two recessive, race-specific adult-plant genes in VA96W-270. At least one gene was common in both lines. Stripe rust resistance in VA96W-270V was controlled by one recessive all-stage gene and one dominant adult-plant gene. Broad-sense heritability as estimated by variance component methods ranged from 0.56 to 0.96, whereas narrow-sense heritability estimated in standard units ranged from 0.29 to 0.51. Moderate heritability suggests the resistance could be incorporated into other cultivars.