title: Coat protein mutations in an attenuated Cucumber mosaic virus encoding mutant 2b protein that lacks RNA silencing suppressor activity induces chlorosis with photosynthesis gene repression and chloroplast abnormalities in infected tobacco plants.
abstract: In tobacco plants, the Cucumber mosaic virus (CMV) pepo strain induces mosaic symptoms, including pale green chlorosis and malformed tissues. Here, we characterized the involvement of 2b protein and coat protein (CP) in the development of mosaic symptoms. A 2b mutant (R46C) that lacks viral suppressor of RNA silencing (VSR) activity showed an asymptomatic phenotype with low levels of virus accumulation. Tomato spotted wilt virus NSs protein did not complement the virulence of the R46C, although it did restore high-level virus accumulation. However, R46C mutants expressing mutated CP in which the amino acid P129 was mutated to A, E, C, Q, or S induced chlorosis that was associated with reduced expression of chloroplast and photosynthesis related genes (CPRGs) and abnormal chloroplasts with fewer thylakoid membranes. These results suggest that the CP of the CMV pepo strain acquires virulence by amino acid mutations, which causes CPRG repression and chloroplast abnormalities.
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan. Electronic address: tomochi@plant.osakafu-u.ac.jp.
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Mochizuki
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Yamazaki
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Wada
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
authors.forename: Satoshi T
authors.initials: ST
authors.lastname: Ohki
mesh_terms: D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000473:pathology* / Q000821:virology; D017799:Cucumovirus / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis; D010935:Plant Diseases / Q000821:virology*; D014026:Nicotiana / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C404227:2b protein, cucumber mosaic virus; D036022:Capsid Proteins; D050505:Mutant Proteins; D014764:Viral Proteins; D037521:Virulence Factors
keywords: 2b Protein; Chloroplast; Chlorosis; Coat protein; Cucumber mosaic virus; Tobacco; Viral suppressor