Linkage of genes conferring specific resistance to oat crown rust in diploid Avena

The inheritance of resistance to an isolate of crown rust race 276 was investigated in four diploid oat lines. F3 families derived from Avena strigosa C.I. 2630 x Avena nuda C.I. 9009, Avena wiestii C.I. 1994 x Avena strigosa C.I. 3815, and C.I. 3815 x C.I. 2630 were inoculated at the seedling stage and evaluated 9-12 days later. Segregation of the F3 families indicated that C.I. 2630 and C.I. 3815 each possess one dominant gene that conditions resistance to race 276. The alleles conferring resistance occur at two different loci, separated by 17 cM on the same chromosome, and appear to be complementary. C.I. 3815 may have an additional recessive resistance allele at a different locus on the same chromosome, 19 cM from its other resistance gene locus.