Differentiation of virulence in Rhynchosporium secalis in the Hokuriku district [Japan] and sources of resistance to the pathogen
1998
Fukuyama, T. (Niigata Univ. (Japan). Faculty of Agriculture) | Yamaji, S. | Nakamura, H.
Variation of virulence in Rhynchosporium secalis (Oud.) Davis distributed in the Hokuriku district was investigated by seedling infection test using 14 differential barley cultivars. A total of 38 cultures were isolated from the infected leaves of Minorimugi, a leading variety in the Hokuriku area, in 1992, 1993 and 1995 from various locations. The 38 isolates showed a complex variation in the virulence pattern and could be classified into 36 different pathotypes according to the virulence spectra to the differentials. Based on the cluster analysis of the reactions of 14 differentials, a geographical cline for virulence was suggested; the isolates from the southern part of the district (Fukui, Ishikawa and Toyama) were more virulent to the differentials than those from the northern part (Yamagata and Niigata). This fact suggests that the virulence of the fungus is conditioned by not only race-specific gene(S) but also by some genes with interactions such as additive or complementary effects. Among the 14 differentials, Brier, Turk and Osiris were highly resistant to the 38 isolates. It appeared that the resistance of these 3 cultivars was controlled by different gene(s) from Rh, Rh4, Rh5, Rh6 or Rh10, since other differentials with the same genotype were attacked by many of the isolates. The 17 cultivars, which had been already selected for the resistance to the Niigata isolate, were tested by 32 of the 38 isolates above mentioned, and 3 cultivars, Turkey 22, Trukey 208 and Carre 26, were confirmed to be highly resistant to all the isolates. It was concluded that these cultivars including Brier, Turk and Osiris are highly suitable materials for breeding for resistance to scald in the Hokuriku district
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