title: Quantitative and qualitative involvement of P3N-PIPO in overcoming recessive resistance against Clover yellow vein virus in pea carrying the cyv1 gene.
abstract: In pea carrying cyv1, a recessive gene for resistance to Clover yellow vein virus (ClYVV), ClYVV isolate Cl-no30 was restricted to the initially infected cells, whereas isolate 90-1 Br2 overcame this resistance. We mapped the region responsible for breaking of cyv1-mediated resistance by examining infection of cyv1 pea with chimeric viruses constructed from parts of Cl-no30 and 90-1 Br2. The breaking of resistance was attributed to the P3 cistron, which is known to produce two proteins: P3, from the main open reading frame (ORF), and P3N-PIPO, which has the N-terminal part of P3 fused to amino acids encoded by a small open reading frame (ORF) called PIPO in the +2 reading frame. We introduced point mutations that were synonymous with respect to the P3 protein but nonsynonymous with respect to the P3N-PIPO protein, and vice versa, into the chimeric viruses. Infection of plants with these mutant viruses revealed that both P3 and P3N-PIPO were involved in overcoming cyv1-mediated resistance. Moreover, P3N-PIPO quantitatively affected the virulence of Cl-no30 in cyv1 pea. Additional expression in trans of the P3N-PIPO derived from Cl-no30, using White clover mosaic virus as a vector, enabled Cl-no30 to move to systemic leaves in cyv1 pea. Susceptible pea plants infected with chimeric ClYVV possessing the P3 cistron of 90-1 Br2, and which were therefore virulent toward cyv1 pea, accumulated more P3N-PIPO than did those infected with Cl-no30, suggesting that the higher level of P3N-PIPO in infected cells contributed to the breaking of resistance by 90-1 Br2. This is the first report showing that P3N-PIPO is a virulence determinant in plants resistant to a potyvirus.
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
authors.forename: Sun Hee
authors.initials: SH
authors.lastname: Choi
authors.forename: Yuka
authors.initials: Y
authors.lastname: Hagiwara-Komoda
authors.forename: Kenji S
authors.initials: KS
authors.lastname: Nakahara
authors.forename: Go
authors.initials: G
authors.lastname: Atsumi
authors.forename: Ryoko
authors.initials: R
authors.lastname: Shimada
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hisa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Naito
authors.forename: Ichiro
authors.initials: I
authors.lastname: Uyeda
mesh_terms: D015153:Blotting, Western; D002678:Chimera / Q000235:genetics / Q000821:virology; D017931:DNA Primers / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D004926:Escherichia coli; D005453:Fluorescence; D005822:Genetic Vectors; D016296:Mutagenesis; D018532:Pisum sativum / Q000235:genetics* / Q000821:virology; D010935:Plant Diseases / Q000821:virology*; D016133:Polymerase Chain Reaction; D017800:Potyvirus / Q000235:genetics* / Q000472:pathogenicity; D014764:Viral Proteins / Q000235:genetics*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D017931:DNA Primers; D014764:Viral Proteins; D037521:Virulence Factors