First report of Bean common mosaic potyvirus in Western Australia

Bean common mosaic virus (BCMV; Family Potyviridae, genus Potyvirus) infects Phaseolus vulgaris crops in many regions of the world. It is transmitted in a non-persistent manner by aphids and is also readily seed-transmitted (Hongying et al., 2002). The disease it causes decreases crop production. In Australia, BCMV has been reported in New South Wales, Queensland, Tasmania and Victoria, based on serology and amino acid composition (Moghal & Francki, 1976; 1981). However, there is no information about isolates or its origin, and no further confirmation or any sequence data for BCMV from Australia. It has not been reported in the Northern Territory, South Australia or Western Australia.

In July 2004, at Kununurra in the east Kimberly region of Western Australia, P. vulgaris plants with mottle and leaf deformation, severe mosaic, malformation of leaves and pods, downward curling of leaves and reduction in leaf size were observed in the field (Fig. 1). Extracts of symptomatic leaf samples tested positive with generic potyvirus monoclonal antibody in ELISA and infected Chenopodium quonoa, C. amaranticolor and Nicotiana benthamiana when manually inoculated.

For molecular identification, total RNA was isolated from symptomatic leaf tissues using an RNeasy Plant Mini Kit (Qiagen). The RNA samples were tested using RT-PCR and generic potyvirus specific primers that amplify a 1700 bp fragment from the 3' end of the genome [5'GTTTTCCCAGTCACGA C(T)15; 5'GGNAAYAAYAGYGGNCARCC] (Chen et al., 2001). A portion of the PCR product (482 bp) was sequenced at the 3' end (Acc. No. AY850005) and the data compared against other BCMV sequences in GenBank. The isolate shared 97% nucleotide identity with the 'NL1' and 'Type' strains of BCMV (Acc. Nos AY112735 and U55319). This sequence result provides the first reliable confirmation of BCMV in Australia and is the first report of its occurrence in Western Australia.