First report of banana bract mosaic virus in banana in Assam, India.

Abstract

Banana bract mosaic disease was first recorded in 1966 in a plantain cv. Nendran as Kokkan disease of unknown etiology in Kerala. The casual agent was identified as Banana bract mosaic virus (BBrMV, genus Potyvirus, family Potyviridae) (Rodoni et al., 1997). BBrMV causes major losses to banana growers in four southern states of India (Selvarajan and Jeyabaskaran, 2006), but has not been recorded in north and north east region (NER) of India. In June 2016, banana plants of cv. Chini Champa (Syn: Mysore, AAB) showing spindle shaped pinkish to reddish mosaic and streaks symptoms on pseudostem and bracts were observed in a field located in Kahikuchi, Assam. Initially 15 plants were tested to be positive for BBrMV using antigen-coated plate (ACP)-ELISA with BBrMV-specific polyclonal antiserum developed at Indian Council of Agricultural Research-National Research Centre for Banana, Tiruchirappalli. Total RNA was isolated from the leaves of infected plants and RT-PCR was performed using the coat protein gene specific primers (RSR10FP: 5’- ATAGGATCCTCTGGAACGGAGTCAACC-3’ and RSR10RP: 5’- TTCATGTTTCATCCCAAGCAGAG-3’) (Balasubramanian and Selvarajan, 2014). An expected 900 bp size fragment obtained from infected plant was cloned into TA cloning vector pTZ57R/T and sequenced (GenBank accession No. KY369923). No amplification was obtained from healthy plants. Sequence analysis revealed 80-96% and 84-98% identity at the nucleotide and amino acid level, respectively, with other BBrMV isolates. Previously BBrMV was confined to southern India and was not reported from NER of India where wild progenitors of cultivated banana are believed to be originated. The virus should be contained before it can spread into banana germplasm resources in the NER of India and other bananaproducing-countriesin which BBrMV is a quarantine pathogen. To the best of our knowledge, this is the first record of BBrMV infection in the NER of India.