Pathogenic specificity of Puccinia recondita f. sp. tritici in Japan during 1990-1992

Pathogenic races of wheat leaf rust fungus (Puccinia recondita f. sp. tritici) collected in Japan during 1990 to 1992 were identified using a Japanese race differential set, consisting of both international standards and Japanese additionals. Race 1 B was common in Kanto, Chubu, Kinki and chugoku districts. In Hokkaido, various races with wider virulence spectrum than that of race 1 B were detected. Distribution of races was almost the same as that reported during the previous 60 years in Japan. Races which had never been detected earlier, such as race 8 and race 73, were identified from samples collected in Hokkaido. Reactions of 19 Thatcher-backcrossed near-isogonic lines with single leaf rust resistance gene were also examined. Eleven races identified by the Japanese differential set were divided into 27 virulence phenotypes by suing the near-isogonic lines. Only one line with resistance gene Lr24 was resistant to all the cultures tested