Detection of Sweet Potato (Ipomoea batatas L.) Leaf Curl Virus (SPLCV) in Ghana Using Visual Symptomatology and PCR Technique

摘要

Production of sweet potato (Ipomoea batatas L.), despite its high potential for food security, is constrained by viruses which reduce yield by up to 90%. It is therefore important to detect the type of viruses that affect the plant. In this study, Visual symptomatology and PCR-based techniques were used to identify Sweet potato leaf curl viruses. Visual symptomatology revealed virus associated symptoms including vein clearing, interveinal chlorosis, chlorotic spots, upward curling on leaf edges, leafnarrowing and distortion, purpling, blistering and general leaf yellowing in all 22 accessions grown on the field. Disease Incidence (DI) significantly (p<0.05) varied between accessions with US003 having the lowest (20%) while ten accessions had the highest DI (90%) at the end of the study. Sweet potato viral disease symptom severity ranged from mild to moderate (1.70-2.19 mean severity score) in the accessions. However, the index of symptom severity of all plants (ISSap) ranged from 1.08±0.09 to 3.67±0.11 with VOTCR003 having the lowest, suggesting that it is a mildly susceptible accession while VOTCR002 had the highest thus suggesting that it is moderately susceptible to viral diseases. Contrarily, the index of symptom severity of diseased plants(ISSdp) ranged from 2.00±0.25 to 3.75±0.32. Visual symptomatology showed that VOTCR002 had the highest DI, ISSap and ISSdp, suggesting that it is highly susceptible to viral diseases. Ten severely infected accessions were tested for Sweet Potato LeafCurl Virus (SPLCV) using PCR technique. PCR detected the virus in 30% of the accessions.