Yuting Tian

Molecular variability of sweet potato chlorotic stunt virus (SPCSV) and five potyviruses infecting sweet potato in China

To obtain a better understanding of the molecular variation of sweet potato viruses in China, 131 samples were collected from symptomatic sweet potato plants and used for RT-PCR analysis of the heat shock protein 70 (hsp70) gene sequence of sweet potato chlorotic stunt virus (SPCSV) and the coat protein (CP) gene sequences of five potyviruses (SPFMV, SPVC, SPVG, SPLV and SPV2). The hsp70 sequences that were obtained provided evidence for the presence of two distinct strains of SPCSV. Analysis of the CP sequences amplified from the samples indicated that all five potyviruses infect sweet potato in China, and three different strains of SPFMV and two of SPVG were found.

Complete genomic sequence and comparative analysis of the genome segments of sweet potato chlorotic stunt virus in China.

Background Sweet potato chlorotic stunt virus (family Closteroviridae, genus Crinivirus) features a large bipartite, single-stranded, positive-sense RNA genome. To date, only three complete genomic sequences of SPCSV can be accessed through GenBank. SPCSV was first detected from China in 2011, only partial genomic sequences have been determined in the country. No report on the complete genomic sequence and genome structure of Chinese SPCSV isolates or the genetic relation between isolates from China and other countries is available. Methodology/Principal Findings The complete genomic sequences of five isolates from different areas in China were characterized. This study is the first to report the complete genome sequences of SPCSV from whitefly vectors. Genome structure analysis showed that isolates of WA and EA strains from China have the same coding protein as isolates Can181-9 and m2-47, respectively. Twenty cp genes and four RNA1 partial segments were sequenced and analyzed, and the nucleotide identities of complete genomic, cp, and RNA1 partial sequences were determined. Results indicated high conservation among strains and significant differences between WA and EA strains. Genetic analysis demonstrated that, except for isolates from Guangdong Province, SPCSVs from other areas belong to the WA strain. Genome organization analysis showed that the isolates in this study lack the p22 gene. Conclusions/Significance We presented the complete genome sequences of SPCSV in China. Comparison of nucleotide identities and genome structures between these isolates and previously reported isolates showed slight differences. The nucleotide identities of different SPCSV isolates showed high conservation among strains and significant differences between strains. All nine isolates in this study lacked p22 gene. WA strains were more extensively distributed than EA strains in China. These data provide important insights into the molecular variation and genomic structure of SPCSV in China as well as genetic relationships among isolates from China and other countries.

Complete Genome Sequences of Two Sweet Potato Chlorotic Stunt Virus Isolates from China

ABSTRACT Sweet potato chlorotic stunt virus (SPCSV) was first detected in China in 2010, and several partial sequences have been determined for Chinese SPCSV isolates. This report describes the complete genome sequences of two SPCSV isolates from the Guangdong and Jiangsu provinces and will be valuable for understanding the characteristics of SPCSVs in China.

Diversity of Sweepoviruses Infecting Sweet Potato in China

Sweepoviruses (a group of begomoviruses that infect plants in the family Convolvulaceae) have monopartite genomes that consist of a circular, single-stranded DNA molecule. Seventy-three complete genomic sequences of sweepoviruses were characterized from the sweet potato samples collected in China. Eight sweepovirus species, including two novel species with proposed names of Sweet potato leaf curl China virus 2 and Sweet potato leaf curl Sichuan virus 2, were identified among these samples. One species, Sweet potato leaf curl Canary virus, was first identified in China. Among the 13 identified strains of Chinese sweepoviruses, 4 were newly discovered. Sweet potato leaf curl virus had the highest frequency (53.4%) of occurrence in the sweet potato samples from China. The similarities among the 73 sweepovirus genomic sequences were between 77.6 and 100.0%. Multiple recombination events were identified, and 16 recombinant sequences were determined. Recombination was observed between different species and between different strains of the same species. Recombination breakpoints were mainly localized on the intergenic region and in three open reading frames (AC1, AV1, and AV2). This study is the first comprehensive report on the genetic diversity of sweepoviruses in China.