Response of African Yam Bean to Cucumber Mosaic Virus Infection in South-Western Ecology

Abstract

Plant viruses are one of the biotic factors limiting the yield of agricultural crops. The infection of fifteen accessions of African Yam Bean (AYB) by Cucumber Mosaic Virus (CMV) was investigated in three locations in 2016 and 2017 planting seasons. Leaf samples were collected before flowering and were subjected to serological assay using double antibody sandwich Enzyme-linked immunosorbent assay (DAS ELISA). Location, year, accessions and their interactions were significant for CMV titres while location alone was significant for pod number at 1% level of probability. Ibadan had the least occurrence of CMV in 2016 and the virus was absent in the same location in 2017. The occurrence of CMV in Ile-Ife and Kishi was higher in 2016 than in 2017. In each of the two locations, six accessions were positive in 2016 and one accession was positive to CMV in 2017. Three accessions; AYB 45, NGB01349 and TSs152 were not infected with CMV during the two years, implying that the accessions will be good candidates for a breeding program against CMV disease. Principal component analysis revealed that PC1, PC2 and PC3 contributed 28.95%, 18.58% and 12.42% respectively of the total variation observed. Cluster analysis grouped the accessions into three at distance 6.4 with TSs 64 being the only accession in group 1 while the third group comprised ten accessions. Identification of virus resistant genotypes is a prerequisite to a successful breeding program and forms the basis for sustainable disease management. Therefore, AYB 45, NGB01349 and TSs152 can be used in further studies for breeding of resistance varieties of AYB.