Progressive aggregation of Tomato yellow leaf curl virus coat protein in systemically infected tomato plants, susceptible and resistant to the virus

• Published in: Virus research Vol. 171; no. 1; pp. 33 - 43
• Main Authors: Gorovits, Rena, Moshe, Adi, Kolot, Mikhail, Sobol, Iris, Czosnek, Henryk
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2013
• Subjects: Aggregation; Aleyrodidae; Begomovirus; Begomovirus - immunology; Begomovirus - metabolism; Capsid Proteins - genetics; Capsid Proteins - metabolism; chloroplast DNA; coat proteins; cytoplasm; Immuno-localization; leaves; Lycopersicon esculentum; Lycopersicon esculentum - immunology; Lycopersicon esculentum - virology; phloem; Plant Diseases - immunology; Plant Diseases - virology; Plant Leaves - metabolism; Plant Leaves - virology; Plants, Genetically Modified; polymerase chain reaction; single-stranded DNA; Solanum lycopersicum var. lycopersicum; Subcellular Fractions; sucrose; Tomato yellow leaf curl virus; tomatoes; viruses; Aggregation; Begomovirus; Immuno-localization
• ISSN: 0168-1702; 1872-7492
• DOI: 10.1016/j.virusres.2012.09.017

► Tomato yellow leaf curl virus (TYLCV) infects tomato plants. ► Virus ssDNA was found in cytoplasm and nucleus; replicative form only in nucleus. ► TYLCV coat protein aggregates appear in infected cell cytoplasm then in nuclei. ► Only nuclear aggregates contained whitefly-transmissible infectious particles. ► Retarding aggregation is part of the response of resistance to TYLCV. Tomato yellow leaf curl virus (TYLCV) coat protein (CP) accumulated in tomato leaves during infection. The CP was immuno-detected in the phloem associated cells. At the early stages of infection, punctate signals were detected in the cytoplasm, while in the later stages aggregates of increasing size were localized in cytoplasm and nuclei. Sedimentation of protein extracts through sucrose gradients confirmed that progress of infection was accompanied by the formation of CP aggregates of increasing size. Genomic ssDNA was found in the cytoplasm and in the nucleus, while the dsDNA replicative form was exclusively associated with the nucleus. CP–DNA complexes were detected by immuno-capture PCR in nuclear and cytoplasmic large aggregates. Nuclear aggregates contained infectious particles transmissible to test plants by whiteflies. In contrast to susceptible tomatoes, the formation of large CP aggregates in resistant plants was delayed. By experimentally changing the level of resistance/susceptibility of plants, we showed that maintenance of midsized CP aggregates was associated with resistance, while large aggregates where characteristic of susceptibility. We propose that sequestering of virus CP into midsized aggregates and retarding the formation of large insoluble aggregates containing infectious particles is part of the response of resistant plants to TYLCV.