Serological and Molecular Characterisation of Virus Infecting Watermelon (Citrullus lanatus) in Adim-Biase, Cross River State, Nigeria

Watermelon, Citrullus lanatus, (Thunb.) is an annual crop in the Cucurbitaceae family grown for it fruits. It nutritional and medical uses helps in combating some illnesses and maintaining good health. The production of this crop in Nigeria is seriously under threat by virus disease. A survey of some farms in Adim, Biase Local Government Area of Cross River State, Nigeria during the 2019 planting season revealed mosaic and chlorotic symptoms. Mechanical inoculation was performed on young seedlings of Cucumeropsis mannii from watermelon samples showing viral symptoms and latter tested against the universal potyvirus antiserum and further detected by RT-PCR assay using cylindrical inclusion (CI) primer. The amplified cDNA was cloned and the nucleotide sequence determined. The serology result showed that there was positive reaction against the potyvirus antiserum confirming it to be a potyvirus. The gene sequence analysis revealed 86% sequence identity with Algerian watermelon mosaic virus. This is the first report of Algerian watermelon mosaic virus strain infecting watermelon in Nigeria.