Molecular Characterization of a Bipartite Begomovirus and an Alphasatellite Associated with Leaf Curl and Mosaic Disease of Bitter Gourd in Punjab

Abstract

Bitter gourd (Momordica charantia) is an economically important vegetable and medicinal plant that gets infected by a number of viruses. A survey was conducted in and around Jalandhar region of Punjab, India to study viral symptoms in the bitter gourd fields. The plants showed reduced fruit size, upward leaf curling and mosaic symptoms, indicating begomovirus infection. DNA was isolated from the symptomatic leaves and tested for begomovirus infection using group-specific PCR primers. Amplified products were cloned into pMD20-T vector and sequenced. Based on the obtained sequence, new sets of primers were designed and used for amplification of complete DNA-A and DNA-B. Complete DNA-A and DNA-B were cloned in pMD20-T and sequenced. Sequence analysis of the present DNA-A and DNA-B showed their highest identity with Tomato leaf curl New Delhi virus (ToLCNDV). The associated Tomato leaf curl New Delhi alphasatellite was amplified using universal primers, cloned and sequenced. In phylogenetic analysis, the present DNA-A and DNA-B grouped with ToLCNDV isolates and other begomoviruses reported from bitter gourd. Phylogenetic analysis of the present alphasatellite showed its closet identity with Tomato leaf curl New Delhi alphasatellite. Recombination analysis of the DNA-A sequence showed that the present bitter gourd isolate might be a recombinant of Squash leaf curl China virus (SLCChV) as a major parent and Chilli leaf curl virus as a minor parent. Analysis of the DNA-B suggested it to be a recombinant of SLCChV as a major parent and Chyaote enation yellow mosaic virus as a minor parent. The present alphasatellite might be a recombinant of Tomato yellow spot alphasatellite as a major parent and Croton yellow mosaic alphasatellite as a minor parent. The percent identities of the nucleotide and amino acid sequences validate and support the results of the phylogenetic and recombination analyses.