title: Molecular identification of tobacco leaf curl disease in Sichuan province of China.
abstract: BACKGROUND
  Tobacco leaf curl disease (TLCD) is caused by begomoviruses in Geminiviridae, and infected plants exhibit leaf thickening, downward leaf curling, vein swelling as well as stunting symptoms. It is one of the economically important diseases in tropical and subtropical tobacco-growing areas. Seven monopartite begomoviruses have been identified causing TLCD in China.
  
  
  RESULTS
  In this study, two begomoviruses were identified, characterized and polygenetically analyzed to be responsible for TLCD in Sichuan province, China. The complete genomes of two isolates SC230 and SC379 from diseased tobacco samples were cloned and sequenced to be 2738 nucleotides (nts) and 2748 nts in size, respectively. Sequence alignment indicated that SC230 and SC379 were most closely related to Tomato yellow leaf curl China virus (TYLCCNV-CN[CN:Sc226:Mal:12]) and Papaya leaf curl China virus (PaLCuCNV-CN[CN:Gx30:Lyc:03]), with a sequence identity of 99.2 and 99.2 %, respectively. The infection rate of TYLCCNV and PaLCuCNV was 100 and 34.78 %, respectively and the co-infection rate was 34.78 % in fields. Betasatellites of SC230 and SC379 share the highest sequence identity with Tomato yellow leaf curl China betasatellite (TYLCCNB-CN[CN:Sc176:Malva:12]) and TYLCCNB-CN[CN:Yn149:Tom:09], with a sequence identity of 95.2 and 97.2 % respectively. Sequence identity between betasatellites of SC230 and SC379 was 89.6 %. And TYLCCNB was detected in all the samples.
  
  
  CONCLUSIONS
  Co-infection of TYLCCNV and PaLCuCNV was identified in tobacco plants with typical symptoms of TLCD from Sichuan province in China, and this is the first report of PaLCuCNV infecting tobacco in China. TYLCCNV/TYLCCNB disease complex is widespread in tobacco-growing areas in Panzhihua city of Sichuan.
authors.affiliation: Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, People's Republic of China. 15213209185@163.com.
authors.forename: Chenchen
authors.initials: C
authors.lastname: Jing
authors.affiliation: Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, People's Republic of China. wangchunyan1219@163.com.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Wang
authors.affiliation: Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, People's Republic of China. lihai8730@163.com.
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.affiliation: Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, People's Republic of China. wugtu@163.com.
authors.forename: Gentu
authors.initials: G
authors.lastname: Wu
authors.affiliation: Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, People's Republic of China. sunxianchao@163.com.
authors.forename: Xianchao
authors.initials: X
authors.lastname: Sun
authors.affiliation: Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing, 400716, People's Republic of China. qling@swu.edu.cn.
authors.forename: Ling
authors.initials: L
authors.lastname: Qing
mesh_terms: D053839:Begomovirus / Q000145:classification* / Q000235:genetics*; D002681:China; D004279:DNA, Viral; D016679:Genome, Viral; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000821:virology*; D017422:Sequence Analysis, DNA; D014026:Nicotiana / Q000821:virology*
chemical_list: D004279:DNA, Viral