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Molecular analysis indicates that papaya in Bangladesh is a host of multiple begomoviruses

Islam Hamim: Department of Plant & Environmental Protection Sciences, University of Hawaii at Manoa

<div>Papaya (<em>Carica papaya</em>) is one of the important fruit crops in Bangladesh. Papaya plants showing severe leaf curl symptoms distinct from those caused by <em>Papaya ringspot virus</em> were observed in several papaya growing districts in Bangladesh during December 2016. These symptoms and the presence of whitefly infestations on these plants suggested the possibility of begomovirus infection. Forty-five symptomatic leaf samples were collected from seven papaya-growing districts in Bangladesh. Degenerate primers (MkBegAF4/MkBegAR) targeting the coat protein and the partial AC2 protein genes of the DNA-A component of begomoviruses were used in PCR assays for detection of begomoviruses in these samples. A 1.3 kb fragment from DNA-A component of begomoviruses was consistently amplified from 43 out of 45 symptomatic samples. Sanger sequencing and BLASTn analyses of these partial DNA-A component sequences revealed that these virus isolates could be classified into three distinct groups (groups 1, 2, 3).The 29 isolates in group 1 were positive for <em>Tomato leaf curl Bangladesh virus (</em>ToLCBV), while 10 isolates in group 2 and 4 isolates in group 3 were positive for <em>Tomato leaf curl Joydebpur virus </em>(ToLCJoV) and <em>Tomato leaf curl New Delhi virus </em>(ToLCNDV), respectively. The complete DNA-A genome sequences of isolates G34106, P11, and P412 were determined and characterized. G34106, P11, and P412 were most closely related to GenBank accession nos. KM383761 (ToLCBV), KM383750 (ToLCJoV), and KM383742 (ToLCNDV), respectively. All of these begomoviruses had been previously identified as infecting tomato in Bangladesh. Our findings suggest the existence of multiple begomoviruses infections in papaya in Bangladesh, which may pose a serious threat to the papaya industry there.</div>