Kudzu (Pueraria montana), a weed widely distributed in southern China, is common in the Fuzhou region of Fujian Province, where many plants show yellow vein mosaic disease. In September 2008, four leaf samples from different plants exhibiting yellow vein mosaic symptom were collected in suburban district of Fuzhou (25°15′ N, 118°08′ E). Whitefly (Bemisia tabaci) infestation was also observed in this region. Total DNA was extracted from all samples using a CTAB method (4). Universal primers (PA/PB) were used to amplify part of the intergenic region and coat protein gene of DNA-A of begomoviruses (1). An amplicon of approximately 500 bp was obtained from all four samples and then sequenced. Comparison of 500-bp fragments (GenBank Accession Nos. FJ539016-18 and FJ539014) revealed the presence of the same virus (98.8 to 99.4%). A pair of back-to-back primers (Yg3FL-F: 5′-GGATCCTTTGTTGAACGCCTTTCC-3′/Yg3FL-R: 5′-GGATCCCACATGTTTAAAGTAAAGC-3′) were designed to amplify the full-length DNA-A from the Chinese isolate identified as Yg3. Sequence analysis showed that full-length DNA-A of Yg3 isolate comprised 2,729 nucleotides (GenBank Accession No. FJ539014) and shared the highest nucleotide sequence identity (91.9%) with Kudzu mosaic virus (KuMV, GenBank Accession No. DQ641690) from Vietnam. To further test the association of DNA-B fragments with the four samples from southern China, rolling circle amplification (RCA) was performed (3). When RCA products were digested with Sph I, approximately 2.7 kb was obtained from all samples. Yg3 isolate was chosen to be sequenced. Sequence analysis showed that full-length DNA-B of Yg3 isolate comprised 2,677 nucleotides (GenBank Accession No. FJ539015) and shared the highest nucleotide sequence identity (76.8%) with KuMV DNA-B (GenBank Accession No. DQ641691) from Vietnam. Based on the current convention of begomovirus species demarcation of <89% sequence identity cut-off criterion (2), Yg3 was identified as an isolate of KuMV. To our knowledge, this is the first report of association of KuMV with yellow vein mosaic symptom of kudzu in China.
References: (1). D. Deng et al. Annals Appl. Biol. 125:327, 1994. (2). C. M. Fauquet et al. Arch. Virol. 148:405, 2003. (3). D. Haible et al. J. Virol. Methods 135:9, 2006. (4). Y. Xie et al. Chinese Sci. Bull. 47:197, 2002.