Crown rust resistance loci on linkage groups 4 and 13 in cultivated oat

Crown rust, caused by Puccinia coronata, is the major fungal disease of oat, Resistance to crown rust is usually, but not always, controlled by single dominant genes in hexaploid oat (Avena spp,). Hexaploid oat lines A. byzantina cv. Kanota and A. sativa cv. Ogle were found to differ in their responses to the two crown rust isolates, PC54 and PC59. Seventy recombinant inbred lines derived from a cross between these two lines were examined. Analysis of rust infection type data indicates that resistance to both of these isolates is due to multiple loci, with major effects exerted by two loci located on linkage groups 4 and 13 of the molecular map developed from this cross. Additionally, resistance to the two isolates could not be separated unequivocally and so resistance to both isolates is apparently influenced by each of the two loci identified, These results corroborate the growing evidence that the two homoeologous groups containing linkage groups 4 and 13 contain many disease resistance genes.