Survey of Viruses Infecting Herbaceous Forage Legumes in Nigeria

Viral attacks on natural populations of herbaceous forage legumes might have adverse effect on seed and herbage production, hence this study was carried out to investigate the type and incidence of viruses occurring on these plants in Nigeria. Protein A-sandwich (PAS) and antigen-coated plate (ACP) enzyme-linked immunosorbent assays (ELISA) were used to detect ten legume viruses from 100 leaf samples collected from eight species of forage legumes planted in the derived savannah zone (DSZ) and northern guinea savannah zone (NGSZ) of Nigeria. The viruses include Bean common mosaic virus (BCMV) genus Potyvirus, ‘blackeye strain’, Cowpea Moroccan aphid-borne mosaic virus (CABMV) genus Potyvirus, Bean yellow mosaic virus (BYMV), genus Potyvirus, Cucumber mosaic virus (CMV), genus Cucumovirus and Cowpea mottle virus (CPMoV), genus Carmovirus. Others include Southern bean mosaic virus (SBMV), genus Sobemovirus, Cowpea mosaic virus (CPMV), genus Comovirus, Cowpea severe mosaic virus (CPSMV), genus Comovirus, Bean pod mosaic virus, (BPMV), genus Comovirus and Tobacco mosaic virus (TMV), genus Tobamovirus. Infection rate ranged from 50.0% in the DSZ to 15.0% in the NGSZ. Most prevalent virus in the DSZ was CPSMV, detected in 30.0% of the samples tested, while in the NGSZ, BYMV was most prevalent (7.5%). CPSMV was detected in Aeschynomene histrix, Chamaecrista rotundifolia, Mucuna pruriens and Mucuna sp. Seed transmission of viruses is a serious problem.