Molecular detection and characterization of begomoviruses associated with cucurbitaceae vegetables in Sri Lanka

Abstract

The family cucurbitaceae includes certain popular fruits and vegetables grown in various tropical and subtropical areas in the world. However, viral diseases are a major constraint causing heavy economical losses in cucurbits. Although a number of viral diseases have been reported in cucurbits in Sri Lanka, there are no reports of begomoviruses. A whitefly transmitted viral disease with severe leaf curl symptoms has been reported in bitter gourd from Sri Lanka (Momordica charantia), which was suspected to be due to a begomovirus. A PCR assay has been conducted using universal primers (Deng 540 and Deng 541) specific for begomoviruses to detect the viruses associated with various cucurbits showing viral symptoms. The begomovirus associated with bitter gourd was characterized by nucleotide sequence analysis. Infection by begomoviruses in bitter gourd, ridge gourd (Luffa acutangula), pumpkin (Cucurbita maxima), cucumber (Cucumis sativus) and snake gourd (Trichosanthes cucumerina) plants, which showed symptoms of upward leaf curl, leaf mosaic, shortening internodes, mottling, stunting, rosetting, puckering, reduced leaf lamina, fruit malformation and flatterning of tender stems were confirmed by consistent amplification of core coat protein CP gene fragment of 520 bp. No amplification was observed with healthy cucurbit samples. The sequence comparison and phylogenetic analysis of the coat protein gene of begomovirus in bitter gourd (Begomo-Bitter Gourd-Sri Lanka Virus) showed 97% nucleotide identity and a close genetic relationship with the Tomato leaf curl New Delhi virus in bitter gourd found in Pakistan (ToLCNDV-BG).