SCREENING FOR SWEET POTATO (Ipomoea Batatas L.) LEAF CURL VIRUS (SPLCV) AND ITS ELIMINATION USING THERMOTHERAPY-MERISTEM TIP CULTURE TECHNIQUE

Abstract

Despite its high potential for food security, production of sweet potato (Ipomoea batatas L.) is constrained by viruses which reduce yield by 90 %. It is, therefore, essential to detect and eliminate these viruses in elite clones before dissemination to farmers. In this study, we used visual symptomatology and polymerase chain reaction (PCR) techniques to detect Sweet potato leaf curl virus (SPLCV) and eliminated the virus using thermotherapy-meristem tip culture. Visual symptomatology revealed virus associated symptoms, including vein clearing, interveinal chlorosis, chlorotic spots, upward leaf curling, leaf narrowing, purpling, blistering and leaf yellowing in all 22 accessions grown on the field. The disease incidence varied between accessions with US003 having the lowest (20 %), while ten accessions had the highest (90 %). The severely diseased accessions were tested for SPLCV using PCR technique. The technique detected the virus in 30 % of the accessions. Plants that tested positive to PCR assay were grown in the chamber at 35 OC for 4 weeks followed by meristem culture. The regenerants were indexed for SPLCV. Fifty-two percent (52.4 %) of the regenerants were successfully cleaned of the virus. Virus indexing and elimination will enhance the dissemination of disease-free planting materials to farmers.