SWEETPOTATO LEAF CURL VIRUS AND RELATED GEMINIVIRUSES IN SWEETPOTATO

Abstract

Sweetpotato leaf curl diseases have been reported in Taiwan, Japan, and the United States. The causal agent is the whitefly transmitted geminivirus, Sweetpotato leaf curl virus (SPLCV). Viral DNA can be detected in plant samples using polymerase chain reaction (PCR) with SPLCV-specific primers. Of 152 samples of sweetpotato and other Ipomoea species collected from various locations in the USA, only 14 were infected with SPLCV. The virus also was detected in total DNA extracted from I. setosa grafted with sweetpotato genotypes from Brazil, China, Mexico, Puerto Rico, and Taiwan. Selected PCR-amplified viral DNA fragments were cloned and sequenced. Based on the partial AC1 ORF sequences, the phylogenetic relationships among SPLCV-like isolates was determined. The results indicated that SPLCV-like isolates clustered into three groups, and all of them might have evolved from the same common ancestor possibly from the Old World. This study suggests that there might be several other geminiviruses of sweet potato yet to be described.