Investigation on disease incidence, distribution and diversity of Begomoviruses infecting cucurbitaceous crops in North Bengal, India

Abstract

Aim: To study the disease incidence and diversity of Begomovirus infection and crop loss due to spread of virus across different districts of North Bengal. Methodology: Several fields in different districts of North Bengal were surveyed and potential begomoviral-infected samples were collected for further analysis. Total DNA extraction, PCR analysis, sequencing and phylogenetic analysis were conducted. Results: During 2019-2021, ten fields of each district were surveyed and begomoviral occurrence was observed in almost every field. The disease incidence in different districts varied from 15-45%. The highest disease (42.5%) incidence of was observed in the Darjeeling district while the lowest (15%) was recorded from Alipurduar district. The maximum crop loss due to Begomovirus was 64-100% in bitter gourd, 40-80% in cucumber and 20-30% in wax gourd. 153 samples from 6 different cucurbits were collected and analysed. PCR using AV494/AC1048 primers that amplified coat protein region (~550bp) showed 74% of the samples as positive. Upon sequencing and BLAST analysis, ToLCNDV, SLCCV and BGYVV were detected. In phylogenetic analysis, the isolates clustered in three separate clades based on Begomovirus species irrespective of the hosts. Present isolates showed more closeness to Indian and Bangladesh isolates. Interpretation: The documentation of disease severity caused by Begomovirus is of extreme importance for food security of the people. Present study revealed that Begomovirus is present in all the crop field studied. The results indicated an urgent need for the management of the viruses to save crops. Key words: Begomovirus, Cucurbitaceous crops, Disease incidence, North Bengal