Abstract
Abstract
Som S. Mukherjee. Identification and characterization of tobamo and tombusviruses isolated from New Zealand waters.
Water samples from the Pohangina and Manawatu rivers in the North Island of New Zealand near Palmerston North were assayed for infectious plant viruses. Three 20 liter water samples each were prefiltered and virions adsorbed to electropositive Zeta Plus 50S membranes. The eluates were examined for virions by transmission electron microscopy. Rod-shaped particles with a modal length of 300 nm and a width of 18 nm as well as icosahedral particles with a modal diameter of 30 nm with no distinct capsomere arrangement were observed. Three tobamoviruses were identified based on symptoms in Nicotiana tabacum cv Turkish, N. benthamiana, Chenopodium quinoa, and Phaseolus vulgaris cv BT-1. An A260/280 of 1.2, and a buoyant density in CsCl of 1.33 supported the conclusion that all three isolates were tobamoviruses. Maximum parsimony alignments conducted with sequences obtained from primers designed to amplify a 422 bp region within the movement protein gene of tobacco mosaic virus (TMV), a 396 bp region within the RNA dependent RNA polymerase (RdRp) gene of tobamoviruses, a 510 bp region within the ToMV capsid protein gene and a set of degenerate primers to amplify the entire 500 bp capsid protein (CP) region of tobamoviruses, confirmed that there were three distinct tobamoviruses present in water samples from the Pohangina river, which constituted a new strain each of TMV and ToMV, and a new tobamovirus species designated as Pohangina river virus (PRiV). Two distinct tombusvirus isolates were also suspected based on symptoms in Vigna unguiculata. An A260/280 = 1.64, and a buoyant density in CsCl =1.35 supported the conclusion that both isolates were tombusviruses. Maximum Parsimony trees generated from the deduced amino acid sequence of an 820 bp amplicon within the p33 (RdRp) gene and the entire capsid protein gene (500 bp) suggested that both isolates were new tombusviruses, which were designated Turitea creek virus (TuCV) and Manawatu river virus (ManRV) respectively. This is the first report of tombusviruses in New Zealand, as well as the first report of tobamoviruses isolated from water in New Zealand.
Som S. Mukherjee
Candidate for the degree of Doctor of Philosophy July 2011
John D. Castello, Ph.D.
Environmental and Forest Biology
State University of New York College of Environmental Science and Forestry, Syracuse, New York
John D. Castello, Ph.D. __________________