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Poster: Molecular & Cellular Plant-Microbe Interactions: Plant Defense Responses


Wheat streak mosaic virus P1: Defining the minimal region required for the suppression of RNA silencing.
A. KASAMSETTY (1), G. Hein (2), S. Tatineni (1) (1) USDA-ARS and University of Nebraska-Lincoln, U.S.A.; (2) University of Nebraska-Lincoln, U.S.A.

Wheat streak mosaic virus (WSMV) is the most economically important wheat virus in the Great Plains region of the USA. WSMV is the type species of the genus Tritimovirus, family Potyviridae, and is transmitted by the wheat curl mite, Aceria tosichella Keifer. Previously, we reported that WSMV P1 functions as the viral suppressor of RNA silencing (VSR) and pathogenicity enhancer. In this study, we examined the minimal region of P1 required for VSR function. Twenty one deletion mutants of WSMV P1 were generated by progressively deleting from the N- and C-terminal regions. VSR assays were conducted by agro-infiltration of deletion mutants in pCASS4 together with the 35S-GFP into Nicotiana benthamiana leaves. WSMV P1 with deletions comprising up to 23 amino acids at the N-terminal region exhibited VSR activity, while deletion of N-terminal 25 amino acids completely abolished the VSR activity. In contrast, even a single amino acid at the C-terminus is indispensable for VSR activity of P1, suggesting that the C-terminal region of WSMV P1 is crucial for VSR activity. Mechanistic studies of WSMV P1 in VSR activity will be discussed.