Inheritance of Resistance to Two Races of Leaf Rust in Dry Edible Bean¹

Abstract

A study was conducted to determine the inheritance of resistance to races 44 and 52 of leaf rust (causal organism Uromyces appendiculatus (Pers. ex Pers.) linger var. appendiculatus ) in the dry edible bean ( Phaseolus vulgaris L.) cultivars ‘T‐39,’ ‘Aurora,’ and ‘Olathe.’ T‐39 and Aurora each express hypersensitive resistance to race 52 but are susceptible to race 44. Olathe is hypersensitive resistant to race 44 and susceptible to race 52. Crosses were made between these cultivars and with ‘UI‐114,’ a pinto bean cultivar susceptible to both races. Resistance of Ft progeny and segregation ratios within F 2 populations and among F3 progeny from individual F 2 plants of crosses with UI‐114 indicated that resistance to each race was controlled by a single, dominant gene. Segregation ratios of the F 2 population and F5 progeny from individual Fj plants of the cross Olathe ✕ T‐39, inoculated with race 44 only, indicated that complementary dominant genes controlled resistance to race 44. Segregation ratios of genes for resistance to races 44 and 52 in progenies of Olathe ✕ Aurora indicated independent assortment without epistasis. The following tentative genotypes for rust reaction of the cultivars studied are proposed: Olathe ‐ Ur a Ur a Ur c Ur c the cultivars studied are proposed: Olathe ‐ Ur a Ur a Ur c Ur c the cultivars studied are proposed: Olathe ‐ Ur a Ur a Ur c Ur c ur b ur b ; T‐39 ‐ ur a ur a ur c ur c Ur b Ur b ; Aurora ‐ ur a ur a Ur c Ur c Ur b Ur b ; UI‐114 ‐ ur a ur a Ur c Ur c ur b ur b .