The distinct disease phenotypes of the common and yellow vein strains of Tomato golden mosaic virus are determined by nucleotide differences in the 3'-terminal region of the gene encoding the movement protein.
In Nicotiana benthamiana, the common strain of the bipartite geminivirus Tomato golden mosaic virus (csTGMV) induces extensive chlorosis whereas the yellow vein strain (yvTGMV) produces veinal chlorosis on systemically infected leaves. In Datura stramonium, csTGMV produces leaf distortion and a severe chlorotic mosaic whereas yvTGMV produces only small chlorotic lesions on systemically infected leaves. Genetic recombination and site-directed mutagenesis studies using infectious clones of csTGMV and yvTGMV have identified a role in symptom production for the gene encoding the movement protein (MP). The MP amino acid at position 272, either valine (csTGMV) or isoleucine (yvTGMV), influenced symptoms in both hosts by inducing an intermediate phenotype when exchanged between the two strains. Exchange of an additional strain-specific MP amino acid at position 288, either glutamine (csTGMV) or lysine (yvTGMV), resulted in the change of symptom phenotype to that of the other strain. In situ hybridization analysis in N. benthamiana demonstrated that there was no qualitative difference in the tissue distribution of the two strains although csTGMV accumulated in higher amounts, suggesting that the efficiency of virus movement rather than distinct differences in tissue specificity of the strains is responsible for the symptom phenotypes.
Saunders
Keith
K
Department of Virus Research, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK1.
Wege
Christina
C
Universität Stuttgart, Biologisches Institut, Lehrstuhl für Molekularbiologie und Virologie der Pflanzen, Pfaffenwaldring 57, 70550 Stuttgart, Germany2.
Veluthambi
Karuppannan
K
Department of Virus Research, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK1.
Jeske
Holger
H
Universität Stuttgart, Biologisches Institut, Lehrstuhl für Molekularbiologie und Virologie der Pflanzen, Pfaffenwaldring 57, 70550 Stuttgart, Germany2.
Stanley
John
J
Department of Virus Research, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK1.
D020413:3' Untranslated Regions / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D004279:DNA, Viral / Q000032:analysis; D013286:Datura stramonium / Q000821:virology; D017791:Geminiviridae / Q000235:genetics* / Q000472:pathogenicity; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D010935:Plant Diseases / Q000821:virology; D053830:Plant Viral Movement Proteins; D010946:Plants, Medicinal; D010947:Plants, Toxic; D011995:Recombination, Genetic; D014026:Nicotiana / Q000821:virology; D014764:Viral Proteins / Q000235:genetics*
D020413:3' Untranslated Regions; D004279:DNA, Viral; D053830:Plant Viral Movement Proteins; D014764:Viral Proteins