First report on race and virulence characterization of Puccinia graminis f. sp. avenae and resistance of oat cultivars in China

The economic importance of oat stem rust is becoming more recognized with the increases of oat cultivated acreage and the disease damage in China. However, there is still no information on races of the pathogen and resistance of oat cultivars. In 2012 and 2013, 26 Puccinia graminis f. sp. avenae (Pga) isolates were obtained from 11 oat stem rust samples collected from oat fields in Hebei province, one of China’s major oat growing provinces. The isolates were tested on 16 Pg single-gene lines that have been used to differentiate Pga races in North America. From the isolates, three races, TKR, TJM and TKM, were identified at 61.6, 30.8 and 7.6 % frequencies, respectively. Virulences to resistance genes Pg1, Pg2, Pg3, Pg4, Pg8, Pg9, Pg12, Pg16 and the gene(s) in the universally susceptible variety “Marvellous” were detected at 100 % frequency, to Pg10 at 69.2, to Pg13 at 61.6, to Pg-a at 61.6 %, and to the gene(s) in Rodney 0 at 84.6 %. No virulence to Pg6 and Pg15 was observed. The above races were used to evaluate the resistance in oat cultivars as seedlings grown in a greenhouse. Of 35 oat cultivars tested, only 13 (37.1 %) were resistant to all three races. This is the first study to identify Pga races and oat stem rust resistance in Chinese oat cultivars.