Both structural and non-structural forms of the readthrough protein of cucurbit aphid-borne yellows virus are essential for efficient systemic infection of plants

• Published in: PloS one 2014-04, Vol.9 (4), p.e93448-e93448
• Main Authors: Boissinot, Sylvaine, Erdinger, Monique, Monsion, Baptiste, Ziegler-Graff, Véronique, Brault, Véronique
• Format: Article
• Language: English
• Subjects: Aphididae; Aphidoidea; Bioinformatics; Biology and life sciences; Coat protein; Cucumis sativus - metabolism; Cucumis sativus - virology; Diseases and pests; Disseminated infection; Flowers & plants; Host-Pathogen Interactions; Infections; Insects; Leaves; Life Sciences; Luteoviridae - genetics; Luteoviridae - metabolism; Luteoviridae - ultrastructure; Mints (Plants); Mutants; Mutation; Plant Diseases - virology; Plant viruses; Plants - virology; Proteins; Reading Frames; Research and Analysis Methods; RNA, Viral - genetics; RNA-Directed DNA Polymerase - genetics; Structural forms; Systemic diseases; Viral Proteins - chemistry; Viral Proteins - genetics; Virion; Virions; Virology; Viruses; Yellows
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0093448

Cucurbit aphid-borne yellows virus (CABYV) is a polerovirus (Luteoviridae family) with a capsid composed of the major coat protein and a minor component referred to as the readthrough protein (RT). Two forms of the RT were reported: a full-length protein of 74 kDa detected in infected plants and a truncated form of 55 kDa (RT*) incorporated into virions. Both forms were detected in CABYV-infected plants. To clarify the specific roles of each protein in the viral cycle, we generated by deletion a polerovirus mutant able to synthesize only the RT* which is incorporated into the particle. This mutant was unable to move systemically from inoculated leaves inferring that the C-terminal half of the RT is required for efficient long-distance transport of CABYV. Among a collection of CABYV mutants bearing point mutations in the central domain of the RT, we obtained a mutant impaired in the correct processing of the RT which does not produce the RT*. This mutant accumulated very poorly in upper non-inoculated leaves, suggesting that the RT* has a functional role in long-distance movement of CABYV. Taken together, these results infer that both RT proteins are required for an efficient CABYV movement.