شناسايي سويه هاي ويروس موزاييك سويا (SMV) در استانهاي مازندران و گلستان

A Detection of Soybean Mosaic Virus Strains in Mazandaran and Golestan Provinces

Soybean mosaic virus (SMV) occurs in all soybean- producing regions worldwide. The damage due to infection by SMV vary , depending on the host cultivar, strain of the virus, and environmental factors. An introduction of soybean resistante cultivars is possible through a knowledge of the kind of virus strain prevalent in a region. In this study, efforts were made to detect SMV strains in Mazandaran and Golestan provinces. During June, July and August 2002, 253 samples suspected of being infected with SMV were collected from various soybean fields in these provinces. By serological tests (ELISA, Dot-Blot, and TPIA), 147 samples were found to be infected with SMV. Following biological purification, based on different kinds of symptoms, 47 isolates were selected for further studies. These isolates were classified into four groups (I, II, III, IV) based on reactions of inoculated differential soybean cultivars (Buffalo, Davis, Kwanggyo, Marshall, Ogden, and York). Group-I did not infect any of the resistant cultivars. Two cultivars (Marshall, Ogden), four cultivars (Davis, Marshall, Ogden, York), and three cultivars (Davis, York, Kwanggyo) were infected by SMV groups-II, III, and IV, respectively. Results indicated that identified groups, I, II, III and IV, belong to strains SMV-G1, G3, G4 and G5 [described by Cho and Goodman (1979)], respectively. Two primer pairs (SMV-G2,G7) to prime the amplification of a fragment in the coding region of cylindrical inclusion protein were used in RT-PCR assay for differentiation of strains. All strains produced a 277- bp using SMV-G7 primers. But no fragments were amplified from RNA extracted from any of the strains using SMV-G2 primers. RT-PCR confirmed the results of differentiation of strains based upon reactions of inoculated differential host.