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Within-plant distribution of PVY strain mixture differs spatio-temporally in potato cultivars

Shaonpius Mondal: Cornell University

<div>Our recent studies indicated that the tuber necrotic strain of <em>Potato virus Y</em> (PVY<sup>NTN</sup>) can co-localize with the ordinary strain (PVY<sup>O</sup>) in single epidermal leaf cells of potato and tobacco plants and their cellular distribution changes spatio-temporally.To understand infection dynamics in whole plants and daughter tubers, Red Maria, Cal White, and Pike potato plants were mechanically inoculated either at pre- or at post-flowering stage with all possible heterologous combinations of two PVY<sup>O</sup> and two PVY<sup>NTN</sup> isolates. Systemically infected leaves were collected from different positions on the plant at different times after inoculation and virus composition was quantified by TAS-ELISA. Tubers were collected and tested to determine which viruses were vertically transmitted. PVY<sup>NTN</sup> outcompeted PVY<sup>O</sup> in Pike at nearly all time points and positions. Both strains were equally competitive in Red Maria and Cal White plants early in the infection when inoculated pre-flower, but PVY<sup>NTN</sup> dominated at later stages and in plants inoculated post-flower. Tuber yield was greater in plants inoculated post-flower, but regardless of inoculation time, both virus strains were present in the daughter plants. Relative titer of PVY<sup>NTN</sup> and PVY<sup>O</sup> at the later stages of mother plant development was indicative of what was found in the daughter plants. The overall dynamics of mixed infections differs among cultivars and virus isolates, but it does not change the vertical transmission outcome.</div>

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