Effect of isolates of beet necrotic yellow vein virus with different RNA components on the development of rhizomania symptoms
1990
Tamada, T. (Central Agricultural Experiment Station, Naganuma, Hokkaido (Japan)) | Saito, M. | Kiguchi, T. | Kusume, T.
Japanese field isolates of beet necrotic yellow vein virus (BNYVV) contained RNA-1, RNA-2, RNA-3 and RNA-4, and some isolates, in addition, RNA-5. Field and laboratory isolates of BNYVV with different RNA components were tested by inoculation using virus-carrying Polymyxa betae. The efficiencies of transmission by Polymyxa betae were isolate S (RNA-1+2+3+4+5) = S-34 (RNA-1+2+3+4) over S-45 (RNA-1+2+4+5) over S-4 (RNA-1+2+4) over S-35 (RNA-1+2+3+5) = S-3 (RNA-1+2+3) over S-5 (RNA-1+2+5) over S-0 (RNA-1+2). This indicates that presence of RNA-4 increases the frequency of fungus transmission. All the isolates with RNA-3 caused a massive proliferation of fine rootlets and typical foliage symptoms. In contrast, the other isolates without RNA-3 caused no apparent symptoms in shoots and roots of sugar beet. In glasshouse tests, a severe reduction in sugar content and root weights was caused by isolates with RNA-3, but not by those without RNA-3, although root weights decreased slightly. The virus content in taproots infected with isolates with RNA-3 was about 10 times greater than that with isolates without RNA-3. These results show that BNYVV RNA-3 not only increases the spread of virus in root tissue, but also is necessary for rhizomania symptoms to develop in roots and shoots of sugar beet, and that it effects greatly a reduction in sugar content
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