Archives of Virology (2008) 153, 105-115

M.L.M. Yambao, H. Yagihashi, H. Sekiguchi, T. Sekiguchi, T. Sasaki, M. Sato, G. Atsumi, Y. Tacahashi, K.S. Nakahara and I. Uyeda (2008)
Point mutations in helper component protease of Clover yellow vein virus are associated with the attenuation of RNA-silencing suppression activity and symptom expression in broad bean
Archives of Virology 153 (1), 105-115
Abstract: Helper component protease (HC-Pro) is a potyvirus-encoded multifunctional protein and a major determinant of symptom expression in a susceptible plant. Here, we show the involvement of clover yellow vein virus (ClYVV) HC-Pro in necrotic symptom expression in broad bean (Vicia faba cv. Wase). In this host, lethal necrosis was induced by ClYVV no. 30, from which a spontaneous, mosaic-inducing mutant (MM) was obtained. Mapping with chimeric viruses between ClYVV no. 30 and MM attributed the symptom attenuation to two mutations at the HC-Pro positions 27 (threonine to isoleucine) and 193 (aspartic acid to tyrosine). Although neither mutant with the single amino acid substitution at position 27 or 193 (ClYVV/T27I or D193Y) induced the lethal necrosis, ClYVV/T27I still retained the ability to induce necrotic symptoms, but ClYVV/D193Y scarcely did so. The virus accumulation of ClYVV/D193Y was also lower than that of ClYVV no. 30. The mutations, T27I and D193Y, are located in a putative zinc finger domain and in one (N-terminal) of the two RNA binding domains, respectively, of HC-Pro. RNA-silencing suppression (RSS) activity of P1/HC-Pro in Nicotiana benthamiana was weakened by both mutations. Our results suggest a correlation between viral virulence and RSS function and the importance of the two domains in HC-Pro.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Ichiro Uyeda, Kenji S. Nakahara

Research topic(s) for pests/diseases/weeds:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Clover yellow vein virus	Broad/faba bean (Vicia faba)