Morpho-molecular Identification and Pathogenicity of Fusarium oxysporum Pathogens Associated with Vascular wilt in Cowpea (Vigna unguiculata L.)

Fusarium oxysporum (Fo), causes vascular wilt in cowpea is a serious pathogen, which leads to severe yield loss and high plant mortality. Variability among the pathogen is very low, due to the lack of sexual reproduction, and low mutation rate. In this study ten different isolates of Fo, collected from various of locations, were evaluated and tested for morphology, molecular biology, and pathogenicity as well. Fo consists of asexual spores, macroconidia, microconidia and chlamydospores, with varied dimensions and produced some pigments in culture media. Sand maize media (10%) was used in pathogenicity test and was found the best than other methods for screening Fo in cowpea. The Fo DNA were amplified with Internal Transcribed Spacer (ITS) primer and the obtained sequences were deposited in the gene bank (GenBank) database. The sequences were compared with the available database and showed 99-100% homology with Fo. Whereas, the phylogenetic study revealed that the isolates were not distant from Fusarium species. The phylogenetic analysis helps to understand the evolutionary relationship among the species identified.