Attenuated Isolates of Soybean Mosaic Virus Derived at a Low Temperature. Y. Kosaka, Plant Pathologists, Kyoto Agricultural Research Institute, Kameoka, Kyoto 621, Japan. T. Fukunishi, Plant Pathologists, Kyoto Agricultural Research Institute, Kameoka, Kyoto 621, Japan. Plant Dis. 77:882-886. Accepted for publication 20 May 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0882.

Attenuated isolates of soybean mosaic virus (SMV) were derived when black soybean (Glycine max cv. Shin Tambaguro) seedlings, inoculated with a virulent SMV isolate, were maintained at 15 C for 14 days, or alternatively, for 30 days. Two isolates obtained (designated Aa15-M1 and Aa15-M2), were serologically and biochemically similar to the initial isolate. However, they differed from the initial isolate in aphid and seed transmissibility, and in replication in soybean plants. In greenhouse and field experiments, Aa15-M1 and Aa15-M2 were effective in cross-protection against virulent SMV strains.