Characterization of Seed Transmission of Soybean Mosaic Virus in Soybean

Infection by Soybean mosaic virus (SMV) is recognized as a serious, long-standing threat in most soybean (Glyince max (L.)Merr.) producing areas of the world. The aim of this work was to understand how SMV transmits from infected soybean maternal tissues to the next generation by investigating the possible routes and amounts of seed transmission of SMV. Analysis of seeds at various reproductive stages revealed that SMV infects all parts of the seed, including the embryo, cotyledon and testa. In situ hybridization and immunofluorescence studies detected the presence of negative sense RNA and dsRNA in the suspensor base regions and embryonic tissues. Ultrastructural studies revealed the hallmark pinwheel aggregates of cylindrical inclusions in the infected cells of leaves and seed embryos. Up to 26% of SMV-positive seeds were recorded from the infected Williams 82 cultivars. Taken together, these results suggest that the seed embryo is a potent source for SMV transmission