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Oral: Virus-Host Interactions


Potato virus Y strains co-localize and compete in single epidermal leaf cells
S. MONDAL (1), S. Mondal (1), S. Gray (1), M. Ghanim (2) (1) Cornell University, U.S.A.; (2) Volcani Center, Israel

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In recent years, recombinant strains of Potato virus Y (PVY) have become predominant in U.S. potato crops; whereas the parental PVY strains have been disappearing. Often multiple PVY strains are found in the same field and occasionally within the same plant, but little is known about how they interact or compete within the plant. Here, we examine the spatial and temporal dynamics of PVY strain infection at the cellular and tissue levels in different hosts. Immunofluorescence and confocal microscopy was used to localize mixtures of PVY strains (PVYO and PVYNTN) in epidermal leaf cells of ‘Samsun NN’ tobacco or ‘Red Maria ‘potato. We observed that both strains systemically infect tobacco and are co-localized in cells of all leaves; however their relative prevalence changes over time. Early in infection when mosaic symptoms are observed, PVYO predominates the infection although PVYNTN is present in some cells. As infection progresses and veinal necrosis is observed, PVYNTN becomes the prevalent virus in those tissues outcompeting PVYO. Co-localization of PVYO and PVYNTN was also found in epidermal cells of potato leaves with almost all cells being infected with both viruses. Co-localization of virus strains in single cells is not a widely used approach for understanding interactions among them. The apparent non-antagonistic interaction among PVY strains could explain the multitude of emerging recombinant PVY strains discovered in potato in recent years.