During two growing seasons in years 2000 and 2001, soybean leaf samples suspected of soybean mosaic virus were collected from various soybean fields in Mazandaran and Gorgan, Northeast Iran provinces. Soybean seed samples obtained, were sown in pots to investigate SMV infections under greenhouse conditions. SMV infections in the field were quite varied and thus could not be used to demonstrate the rate of SMV infection. For propagation of the virus, several susceptible test plants such as different soybean cultivars were inoculated and employed in the greenhouse study. In addition, serological tests, using specific polyclonal antisera against SMV, were employed to detect the virus in the samples. SMV was purified applying two different methods. Electron microscopy showed the virus particles to be filamentous and rod shaped. The best serological agar media in double diffusion test included 0.8g agarose, 0.85 g NaCl, 0.25g SDS and 0.025g NaN3 in 100ml distilled water.During the course of the study, SMV was found to be the most predominant virus in the area, and mosaic was the most common symptom of SMV infection. The distribution of SMV was similar in either of the two provinces. In a few soybean fields in Gorgan (Hashemabad) and Mazandaran (Dashte Naze, Neka, Gaz, Jooibar and Badeleh) provinces, SMV infection was extremely serious. Only 10-15 percent of seeds sown gave rise to infected seedlings. Western immunoblot analysis revealed a single coat protein subunit of about 28 kDa in the purified viral protein as well as in SMV infected leaf samples.
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