First Report of Sweet potato chlorotic stunt virus Infecting Sweet Potato in China

Sweet potato chlorotic stunt virus (SPCSV) (genus Crinivirus, family Closteroviridae) is a whitefly-transmitted co-infectant of the sweet potato virus disease (SPVD), which can cause severe yield losses in sweet potato (Ipomoea batatas (L.) Lam.) (2,3). One isolate was obtained in Guangdong Province in August 2009 from sweet potato plants of cv. Guangshu No. 87 exhibiting symptoms typical of SPVD, including stunting, leaf distortion, vein clearing, and chlorosis. Leaf extracts from the symptomatic plants tested positive for SPCSV by nitrocellulose membrane ELISA with antisera specific for SPCSV obtained from the International Potato Center. Total RNA was extracted from young leaves of sweet potato and reverse transcription-PCR was performed by using primer pairs SPSP1 (5'-ATGRMTACTGRCAAAGTAAACGATG-3') and SPSP4 (5'-TCAACAGTGAAGACCRGYACCRGTCAA-3') corresponding to the capsid protein (CP) gene of SPCSV. Expected DNA fragments of 774 bp were obtained from symptomatic plants but not from control plants. The 774-bp fragments obtained by amplification were purified and cloned into the PMD19-T vector (TaKaRa, Dalian, China). Recombinant plasmids were then transformed into competent cells of Escherichia coli strain Jm109. Sequencing of the fragments from two individually clones plasmids yielded a nucleotide sequence (GenBank Accession No. HM773432) with 97.4 to 98.7% similarity to the CP gene of East African SPCSV isolates (1). To our knowledge, this is the first report of SPCSV in sweet potato fields from China. This virus may threaten sweet potato production in China, so cultivars and germplasm should be evaluated for resistance. References: (1) V. Aritua et al. J. Phytopathol. 156:181, 2008. (2) R. W. Njeru et al. Ann. Appl. Biol. 145:71, 2004. (3) G. A. Schaefer and E. R. Terry. Phytopathology 66:642, 1976.