Biological and molecular characterization of Bean common mosaic virus associated with vanilla in India

Abstract

Bean common mosaic virus (BCMV) associated with vanilla (Vanilla planifolia Andrews) in India was characterised based on host reaction and coat protein (CP) sequence properties. The virus caused mosaic, leaf and stem necrosis, leaf distortion and stunting followed by drying of aerial adventitious roots. Leaf-dip preparation of infected vanilla leaves revealed flexuous filamentous particles characteristic of a Potyvirus. In mechanical inoculation tests, the virus was transmitted to plant species under family Chenopodiaceae, Fabaceae and Solanaceae. Vigna unguiculata and Nicotiana benthamiana were found suitable propagation hosts of BCMV. The virus was partially purified from inoculated V. unguiculata leaves and the molecular weight of the viral coat protein was measured to be 34 kDa. Partial NIB and CP gene (c.a. 850 bp) of the virus was amplified using reverse transcriptase-polymerase chain reaction (RT-PCR) and finally cloned and sequenced. The cp gene contained 823 nucleotides potentially coding for 274 amino acids. The present BCMV isolate showed 87-96% nucleotide and 87-98% amino acid sequence identities with other BCMV isolates/strains. The isolate showed maximum identity of 96% and 98% at nucleotide and amino acid level, respectively, with Blackeye (Blk1) strain of BCMV indicating its closeness to cowpea infecting BCMV isolates. This is the first report of occurrence of BCMV on V. planifolia from India