A Major QTL for Adult Plant Crown Rust Resistance in Oat

Crown rust, caused by Puccinia coronata Corda f. sp. avenae Eriks., is the most important disease of oat worldwide. Adult plant resistance (APR) is believed to be a durable rust management strategy. The APR crown rust resistance in the oat line MN841801 has been effective for more than 30 years. Genetic control of APR was studied in a population of 163 recombinant inbred lines derived from a cross of AC Assiniboia, a susceptible cultivar, by the APR line MN841801. The objective was to identify QTLs for APR under field conditions. The population was phenotyped in Saskatchewan and Manitoba for APR with the crown rust isolate CR251 (race BRBB) in six environments. The new 6K Oat Infinium SNP array and Diversity Array Technology (DArT) markers were used for genotyping. The SNP and DArT data integrated very well and the map generated was about 1,600 cM. A major QTL was identified that explained up to 76% of the APR phenotypic variance. The QTL was significant in all the environments and we report the first APR QTL in oat with a major and consistent effect in multiple environments. Two other populations, AC Medallion × MN841801 and Makuru × MN841801, are being assessed for validation of the MN841801 APR QTL. The  MN841801 APR QTL appears to be a suitable candidate for use in marker-assisted breeding and also an ideal target for map-based cloning.