The movement protein (NSm) of Tomato spotted wilt virus is the avirulence determinant in the tomato Sw-5 gene-based resistance.

Abstract

The avirulence determinant triggering the resistance conferred by the tomato gene Sw-5 against Tomato spotted wilt virus (TSWV) is still unresolved. Sequence comparison showed two substitutions (C118Y and T120N) in the movement protein NSm present only in TSWV resistance-breaking (RB) isolates. In this work, transient expression of NSm of three TSWV isolates [RB1 (T120N), RB2 (C118Y) and non-resistance-breaking (NRB)] in Nicotiana benthamiana expressing Sw-5 showed a hypersensitive response (HR) only with NRB. Exchange of the movement protein of Alfalfa mosaic virus (AMV) with NSm supported cell-to-cell and systemic transport of the chimeric AMV RNAs into N. tabacum with or without Sw-5, except for the constructs with NBR when Sw-5 was expressed, although RB2 showed reduced cell-to-cell transport. Mutational analysis revealed that N120 was sufficient to avoid the HR, but the substitution V130I was required for systemic transport. Finally, co-inoculation of RB and NRB AMV chimeric constructs showed different prevalence of RB or NBR depending on the presence or absence of Sw-5. These results indicate that NSm is the avirulence determinant for Sw-5 resistance, and mutations C118Y and T120N are responsible for resistance breakdown and have a fitness penalty in the context of the heterologous AMV system.

DOI: 10.1111/mpp.12142
0100200300201520162017
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@article{Peir2014TheMP, title={The movement protein (NSm) of Tomato spotted wilt virus is the avirulence determinant in the tomato Sw-5 gene-based resistance.}, author={Ana Ma Peir{\'o} and M. Carmen Ca{\~n}izares and Luis Rubio and Carmelo L{\'o}pez and Enrique Moriones and Jose Aramburu and Jes{\'u}s {\'A}ngel S{\'a}nchez-Navarro}, journal={Molecular plant pathology}, year={2014}, volume={15 8}, pages={802-13} }