Tomato yellow leaf curl virus accumulates in vesicle-like structures in descending and ascending midgut epithelial cells of the vector whitefly, Bemisia tabaci, but not in those of nonvector whitefly Trialeurodes vaporariorum
2013
Uchibori, M. (The University of Tokyo, Kashiwa, Chiba (Japan). Graduate School of Frontier Sciences, Department of Integrated Biosciences) | Hirata, A. | Suzuki, M. | Ugaki, M.
Begomoviruses are transmitted by a single species of vector insect, the whitefly Bemisia tabaci, in a circulative manner. However, the mechanisms of this strict vector specificity have not been clarified. By immunoelectron microscopy, we showed that a begomovirus, Tomato yellow leaf curl virus (TYLCV), can enter midgut epithelial cells of the vector whitefly B. tabaci but not those of a nonvector whitefly, Trialeurodes vaporariorum, belonging to the same family. In midgut epithelial cells of viruliferous B. tabaci, the virus was localized in vesicle-like structures, suggesting endocytosis as an entry mechanism. These structures were also observed in midgut cells of nonviruliferous B. tabaci that had fed on healthy plants and in those of the nonvector T. vaporariorum that had fed on virus-infected plants. Vesicles containing TYLCV particles were observed most frequently in cells in the anterior part of the descending midgut, suggesting that this is the major entry site. These results clearly demonstrated that the virus-containing vector and nonvector whiteflies differ in the cellular localization of the virus and strongly suggest that a critical step in determining the vector insect specificity of begomoviruses is the entry of the viruses into midgut epithelial cells.
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