Viruses infecting carnations and dianthus species in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science at Massey University

Abstract

Five viruses were detected in commercial carnations and these and a further four occurred in Dianthus species from gardens. Carnation mottle virus (CarMV) and carnation etched ring virus (CERV-50) were widespread in commercial carnations; arabis mosaic virus (ArMV), carnation latent virus (CLV) and carnation necrotic fleck virus (CNFV) were also detected. In Dianthus species CERV-50, CLV and CarMV were the most prevalent, whereas only a low incidence of ArMV, CNFV, carnation ringspot virus (CRSV) and carnation vein mottle virus (CVMV) was found. Two new viruses were detected in Dianthus species: an apparently uncharacterized plant rhabdovirus, named carnation bacilliform virus, with particles ca. 260 x 55nm (in ultrathin sections), and an unidentified isometric virus (D 345) ca. 30nm in diameter. The viruses were characterized by a variety of methods including host range, symptoms, aphid transmission and particle morphology. The three rod viruses CLV, CNFV and CVMV were differentiated by particle morphology and size. Normal lengths for CLV and CVMV were 656nm and 733nm, respectively, while CNFV had particles in the range 1,000-1,450nm. The identity of the polyhedral viruses ArMV, CarMV and CRSV, was confirmed by serology. Carnation etched ring virus was identified by its particle size, ca. 48nm in diameter, and a consistent association with refractile inclusion bodies which were readily observed by light microscopy in epidermal strips stained with phloxine/trypan blue. Cytological observations were made on ultrathin sections of leaves from plants infected with CBV, CERV-50, CLV and CVMV. Aggregates of CBV and CLV particles were observed in the cytoplasm; CERV-50 infected plants contained typical inclusions and particles of the virus; and CVMV induced cylindrical inclusions typical of the potyvirus group