title: Heterologous expression of viral suppressors of RNA silencing complements virulence of the HC-Pro mutant of clover yellow vein virus in pea.
abstract: Many plant viruses encode suppressors of RNA silencing, including the helper component-proteinase (HC-Pro) of potyviruses. Our previous studies showed that a D-to-Y mutation at amino acid position 193 in HC-Pro (HC-Pro-D193Y) drastically attenuated the virulence of clover yellow vein virus (ClYVV) in legume plants. Furthermore, RNA-silencing suppression (RSS) activity of HC-Pro-D193Y was significantly reduced in Nicotiana benthamiana. Here, we examine the effect of expression of heterologous suppressors of RNA silencing, i.e., tomato bushy stunt virus p19, cucumber mosaic virus 2b, and their mutants, on the virulence of the ClYVV point mutant with D193Y (Cl-D193Y) in pea. P19 and 2b fully and partially complemented Cl-D193Y multiplication and virulence, including lethal systemic HR in pea, respectively, but the P19 and 2b mutants with defects in their RSS activity did not. Our findings strongly suggest that the D193Y mutation exclusively affects RSS activity of HC-Pro and that RSS activity is necessary for ClYVV multiplication and virulence in pea.
authors.affiliation: Pathogen-Plant Interactions Group, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Atsumi
authors.forename: Kenji S
authors.initials: KS
authors.lastname: Nakahara
authors.forename: Tomoko Sugikawa
authors.initials: TS
authors.lastname: Wada
authors.forename: Sun Hee
authors.initials: SH
authors.lastname: Choi
authors.forename: Chikara
authors.initials: C
authors.lastname: Masuta
authors.forename: Ichiro
authors.initials: I
authors.lastname: Uyeda
mesh_terms: D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D020125:Mutation, Missense; D018532:Pisum sativum / Q000235:genetics / Q000821:virology*; D010935:Plant Diseases / Q000235:genetics* / Q000821:virology*; D017800:Potyvirus / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D034622:RNA Interference; D014026:Nicotiana / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D014774:Virulence
chemical_list: D014764:Viral Proteins; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus