Molecular identification of tobacco leaf curl disease in Sichuan province of China
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Molecular identification of tobacco leaf curl disease in Sichuan province of China Chenchen Jing, Chunyan Wang, Ke Li, Gentu Wu, Xianchao Sun and Ling Qing*
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. Findings: 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. Conclusion: 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. Keywords: Tobacco, Tomato yellow leaf curl China virus, Papaya leaf curl China virus, Co-infection
Background Geminiviruses are a large family of plant viruses with circular, single-stranded DNA genome encapsidated in unique twinned particles. They consist of seven genera (Mastrevirus, Curtovirus, Topocuvirus, Begomovirus, Becurtovirus, Eragrovirus and Turncurtovirus) on the basis of genome structure, host range and insect vector [1, 2]. Most of the economically important geminiviruses belong to the genus Begomovirus, which are transmitted by Bemisia tabaci to a wide range of dicotyledonous plants [3]. Begomoviruses cause significant economic losses to many crops, including common bean, cotton, cucurbits, okra, tomato, pepper and tobacco [4–7]. In China, TLCD caused by begomoviruses was first observed * Correspondence: [email protected] Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing 400716, People’s Republic of China
in Yunnan and Fujian province in 1982 [8]. Recently, TLCD has occurred in Guangxi and Guangdong [9, 10
