The morphology of Rhizobium loti induced root nodules and the flavolan content of nodulated roots of several Lotus species, Leuceana leucocephala, Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus were examined. Rhizobium loti strain NZP2037 formed effective (Nod+Fix+) nodules on all legumes, but strain NZP2213 formed Nod+Fix+ nodules only on Lotus corniculatus var. cree and ineffective (Nod+Fix−) nodules on all other legumes. The Nod+Fix− nodules developed by NZP2213 showed morphologies ranging from the complete absence of bacteria within “tumour-like” structures to the development of nodules containing bacteria that were either not released or only incompletely released from infection threads. Within nodules formed by NZP2213 on Lotus corniculatus var. hirsutus and Carmichaelia flagelliformis the rhizobia had multiplied extensively within unwalled, plasma membrane bound, infection droplets. Flavolans rich in prodelphinidin, which is toxic towards NZP2213, were present in the roots of Lotus angustissimus, Lotus pedunculatus, Lotus subbiflorus, and Leuceana leucocephala, but only trace amounts of flavolan were found in the roots of Carmichaelia flagelliformis, Ornithopus sativus, and Clianthus puniceus.
Water samples from Turitea Creek and the Manawatu River near Palmerston North, New Zealand were assayed for infectious plant viruses. Twenty liter water samples each were prefiltered and virions adsorbed onto electropositive Zeta Plus 50S membranes. Eluates were examined for virions by transmission electron microscopy. Icosahedral particles with a diameter of 30 nm with no distinct capsomere arrangement were observed. Two distinct tombusvirus isolates were suspected based on symptoms in Vigna unguiculata. An A 260/280 =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 (1100 bp) showed maximum similarity of the isolates from Manawatu river and Turitea creek with Cucumber bulgarian latent virus (60% and 64%, respectively) in the p33 region, and with Maize necrotic streak virus (83%) and Cymbidium ringspot virus (76%), respectively, in the capsid protein region. In accordance with the species demarcation criteria of <87% sequence identity in the capsid protein amino acid sequences established by the ICTV, it is suggested that both isolates are new tombusviruses, for which we propose the names Turitea creek virus (TuCV) and Manawatu river virus (ManRV). This is the first report of tombusviruses in New Zealand.
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