Murraya koenigii (L.) Spreng., a small, strong-smelling umbrageous tree with subcampanulate white flowers belonging to the family Rutaceae, is native to India and southeastern Asia (2). It is distributed across the Indian subcontinent excluding the higher elevations of the Himalayas. In India, the leaves are mainly used for culinary purposes. The leaves are commonly known as curry leaves or ‘sweet neem’. The whole plant including bark, root, leaves, fruits, and fruit pulp is used medicinally. This plant was reported to be a host of Citrus tristeza virus (1). In a survey of potyvirus incidence in the northwestern Himalaya foothills of the Kangra and Hamirpur districts in the state of Himachal Pradesh in 2004, M. koenigii plants showing mosaic symptoms on leaves, typical of a virus infection, were frequently observed. Symptomatic leaves were tested for the presence of several viruses using enzyme-linked immunosorbent assay with specific antibodies. Positive results were obtained with potyvirus group specific antibodies (Agdia, Elkhardt, IN) in triplicate analyses of 5 of 15 leaf samples tested. To further identify the infecting virus, RNA from plants was tested using universal potyvirus primer pair P9502 and CPUP (3) and reverse transcription-polymerase chain reaction to amplify a genome fragment encoding portions of the coat protein and the 3′UTR (3). An amplification product of the expected size (~800 bp) was obtained. The product was cloned into the pGem-T easy vector (Promega, Madison, WI), and three clones were sequenced. The sequence (GenBank Accession No. AJ852504) had 92% identity to Chili vein banding mottle virus, a potyvirus infecting pepper reported from Thailand (GenBank Accession No. U72193). To our knowledge, this is the first report of a potyvirus naturally occurring on a Murraya sp.
References: (1) K. Balaram and K. Ramakrishnan. Curr. Sci. 48:453, 1979. (2) J. D. Hooker. Flora British India 1:502, 1875. (3) R. A. A. van der Vlugt et al. Phytopathology. 89:148, 1999.
