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Poster: Diseases of Plants: New & Emerging Diseases


First report and characterization of Taro bacilliform virus in the USA
M. MELZER (1), K. Dey (1), A. Chan Borges (1), M. Long (1), W. Borth (1), N. Wichitrnithed (1), J. Hu (1), R. Li (2) (1) University of Hawaii, U.S.A.; (2) USDA-ARS, U.S.A.

Taro bacilliform virus (TaBV) is a member of the genus Badnavirus (Family Caulimoviridae) and a pathogen of taro (Colocasia esculenta), an important starch staple in tropical regions. TaBV is transmitted by mealybugs and appears to be widely distributed throughout the tropical Pacific. Taro has cultural, economic and nutritional importance in Hawaii, but only Dasheen mosaic virus and Taro vein chlorosis virus have been reported in the state. We surveyed 328 taro plants from 35 sites on the islands of Kauai, Oahu, Molokai, Maui, and Hawaii for the presence of TaBV by PCR using degenerate badnavirus and TaBV-specific primers. Of these, 171 samples (52%) tested positive using the degenerate primers, but only 153 tested positive using TaBV-specific primers (47%), indicating the presence of novel badnaviruses and/or strains of TaBV in Hawaii’s taro. The 7825 bp genome of one isolate of TaBV was sequenced and found to be 80% identical and 367 bp larger than the only complete TaBV genome in GenBank (accession AF357836), indicating that considerable genetic diversity exists for this virus. PCR, RT-PCR and Southern hybridization assays were conducted and provided evidence that TaBV is integrated into the genome of some Hawaiian taro varieties. TaBV was mechanically inoculated onto eight herbaceous plant species, and after 25 days, TaBV could be detected by PCR in Cucurbita pepo, Pisum sativum, Cucumis sativus, Vigna unguiculata, and Phaseolus vulgaris.