Detection and distribution of viruses infecting hot pepper (Capsicum spp.) in Rwanda

Abstract

Accurate diagnosis is a prerequisite to effective management of plant diseases especially those whose symptoms are not very specific. A survey was conducted from February to March 2018 to detect the presence and determine the distribution of six viruses infecting pepper in Rwanda. A total of 225 symptomatic samples were collected from high, mid and low-altitude zones, and analysed using serology assay with antibodies to cucumber mosaic virus (CMV), potato virus Y (PVY), pepper veinal mottle virus (PVMV), pepper mild mottle virus (PMMoV) and tobacco mosaic virus (TMV). Polymerase chain reaction was used to confirm the results from serology and to test for the presence of pepper vein yellows virus (PeVYV), which has no commercial antibodies. Amplified DNA fragments were sequenced and compared with other known pepper viruses available in the GenBank database. Seventy-three percent of the samples tested positive for at least one of the viruses. CMV, PVY, PVMV, TMV and PMMoV were detected in all zones but PeVYV was detected in the mid and low-altitude areas. CMV was the most widespread and was detected in 48% of the samples, followed by PVMV and PVY in 23.6% and 18.2%, respectively. There were both single (36%) and mixed (34.6%) infections of the viruses. Sequence and phylogenetic analysis confirmed the presence of CMV, PeVYV, PVMV and TMV in the country. This is the first report of TMV, PMMoV and PVY infecting pepper in Rwanda. Efforts towards the development of sustainable management for these viruses should be put in place to improve yields and quality of hot pepper.