Single amino acid substitution in the methyltransferase domain of Paprika mild mottle virus replicase proteins confers the ability to overcome the high temperature-dependent Hk gene-mediated resistance in Capsicum plants.
Capsicum plants harboring the Hk gene (Hk) show resistance to Paprika mild mottle virus (PaMMV) at 32 degrees C but not 24 degrees C. To identify the viral elicitor that activates the Hk-mediated resistance, several chimeric viral genomes were constructed between PaMMV and Tobacco mosaic virus-L. Infection patterns of these chimeric viruses in Hk-harboring plants revealed responsibility of PaMMV replicase genes for activation of the Hk-mediated resistance. The comparison of nucleotide sequence of replicase genes between PaMMV and PaHk1, an Hk-resistance-breaking strain of PaMMV, revealed that the adenine-to-uracil substitution at the nucleotide position 721 causes an amino acid change from threonine to serine at the 241st residue in the methyltransferase domain. Introduction of the A721U mutation into the replicase genes of parental PaMMV overcame the Hk resistance at 32 degrees C. The results indicate that Hk-mediated resistance is induced by PaMMV replicase proteins and that methyltransferase domain has a role in this elicitation.
Matsumoto
Katsutoshi
K
Laboratory of Plant Pathology and Biotechnology, Kochi University, 200 Monobe, Nankoku, Kochi 783-8502, Japan.
Johnishi
Kousuke
K
Hamada
Hiroyuki
H
Sawada
Hiromasa
H
Takeuchi
Shigeharu
S
Kobayashi
Kappei
K
Suzuki
Kazumi
K
Kiba
Akinori
A
Hikichi
Yasufumi
Y
D019943:Amino Acid Substitution; D002212:Capsicum / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D016679:Genome, Viral; D006358:Hot Temperature; D007113:Immunity, Innate; D008780:Methyltransferases / Q000235:genetics; D009154:Mutation; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D017423:Sequence Analysis, RNA; D014027:Tobacco Mosaic Virus / Q000235:genetics; D017898:Tobamovirus / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D014764:Viral Proteins / Q000235:genetics*; D014779:Virus Replication
D012367:RNA, Viral; D014764:Viral Proteins; D008780:Methyltransferases; D012324:RNA-Dependent RNA Polymerase