Evaluation of Seed Transmission of Turnip yellow mosaic virus and Tobacco mosaic virus in Arabidopsis thaliana

The mechanism of virus transmission through seed was studied in Arabidopsis thaliana infected with Turnip yellow mosaic virus (TYMV) and Tobacco mosai c virus (TMV). Serological and biological tests were conducted to identify the route by which the Viruses reach the seed and subsequently are located in the seed. Both TYMV and TMV were detected in seed from infected plants, however only TYMV was seed-transmitted. This is the first report of transmi ssion of TYMV in seed of A. thaliana. Estimating virus seed transmission by grow-out tests was more accurate than enzyme-linked immunosorbent assay du e to the higher frequency of antigen in the seed coat than in the embryo. V irus in the seed coat did not lead to seedling infection. Thus, embryo inva sion is necessary for seed transmission of TYMV in A. thaliana. Crosses bet ween healthy and virus-infected plants indicated that TYMV from either the female or the male parent could invade the seed. Conversely, invasion from maternal tissue was the only route for TMV to invade the seed. Pollination of flowers on healthy A. thaliana with pollen from TYMV-infected plants did not result in systemic infection of healthy plants, despite TYMV being car ried by pollen to the seed.