Research Institute for Bioresources, Okayama University
2-20-1, Chuo, Kurashiki, 710-0046, Japan
Previous research has led to reports of several strains of Barley Yellow Mosaic Virus (BaYMV) (three in Japan; two in Europe) and of several (at least four or five) genes for BaYMV resistance in barley. This study was made to obtain useful information for identifying new sources of genes for BaYMV resistance.
A screening test for BaYMV symptoms was made at Nadasaki, Okayama Prefecture, for three years beginning in 1989, in a field where strain I (Kashiwazaki et al. 1989) of BaYMV was known to be present. A total of 4342 barley cultivars from the world collection of The Germplasm Center of Barley and Wild Plants, Okayama University, were sown in mid-November with two replications. Thirty barley cultivars known to range from resistant to susceptible for the BaYMV were arranged in every sowing row as standards. In mid- to late March, the cultivars were classified into five categories: degree 0 (no symptoms) and degree 1 (slight symptoms) through degree 4 (yellowing and necrosis). Cultivars classified as degree 0 and degree 1 were retained for testing the following year.
Table 1 shows that percentage of frequency of asymptomatic (degree 0) cultivars was the highest among Ethiopian cultivars followed by Japanese ones. Cultivars showing showing severe disease symptoms (degrees 3 and 4) were frequently found among Chinese, Nepalese, South-east Asian, North African, North American and European barleys. In Japan, the frequency of severely susceptible cultivars (degree 4) was more than 50%. Cultivars showing moderate symptoms (degree 2) were frequent among Turkish barleys. The frequency of non-symptomatic cultivars tended to be higher in E-type (Oriental type) than W-type (Occidental type) for brittle rachis (Takahashi, 1987) in the majority of regions and countries excepting India and Ethiopia (Table 2). Furthermore, in Japan and Europe, asymptomatic types were mainly found in six-rowed cultivars (Table 2).
References:
Kashiwazaki, S., Ogawa, K., Usugi, T. and Tsuchizaki, T. 1989: Characterization of several strains of barley yellow mosaic virus. Ann. Phytopath. Soc. Japan 55:16-25.
Takahashi, R. 1987:Genetic features in East Asian barleys. Barley Genetics V:7-20.
1 Present address: 1089-31, Itsukaichi, Kurashiki, 710-0041, Japan