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United States Department of Agriculture

Agricultural Research Service

Research Project: CHARACTERIZING, DETECTING, AND ELIMINATING PATHOGENS TO ENABLE THE SAFE INTRODUCTION OF PLANT GENETIC RESOURCES

Location: National Germplasm Resources

Title: First report of Tomato Yellow Leaf Curl China Virus infecting Panax Notoginseng in China

Authors
item Li, Fan -
item Li, X J -
item Liu, F -
item Li, Y Y -
item Zhang, S Y -
item Li, M R -
item Li, Ruhui

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 25, 2014
Publication Date: May 29, 2014
Citation: Li, F., Li, X., Liu, F., Li, Y., Zhang, S., Li, M., Li, R. 2014. First report of Tomato Yellow Leaf Curl China Virus infecting Panax Notoginseng in China. Plant Disease. http://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-03-14-0255-PDN.

Technical Abstract: Panax notoginseng, an important medicinal herb commonly known as notoginseng, san qi or tian qi, is a species of the genus Panax in the family Araliaceae. The herb is mainly cultivated in Guangxi and Yunnan Provinces of southern China for its root, which is used to treat blood disorders such as blood stasis, bleeding and blood deficiency. In December 2012, Panax yellowing were observed on several P. notoginseng farms with incidences of 5-10% in Wenshan, Yunnan Province. Foliar symptoms included yellowing, shrinking, curling, and blistering. Leaf samples were collected from 15 symptomatic P. notoginseng plants. The samples were initially inspected using negative staining preparations in transmission electronic microscopy, but no distinct virions were observed. Total nucleic acids were extracted from these samples using a CTAB method and used as templates in RT-PCR for presence of criniviruses, tobamoviruses and tospoviruses, but results were also negative. Infestation by whiteflies (Bemisia tabaci) has been a worsening problem on these farms in recent years, suggesting that a whitefly-transmitted begomovirus could be potential causal agent of the symptoms. To explore this possibility, the samples were tested by PCR using degenerate primers BegoAFor1 and BegoARev1 described by Ha et al. (1). Amplicons of approximately 1.2 kb were obtained from 12 of the 15 samples, indicating the presence of a putative begomovirus. These amplicons were cloned and sequenced in both directions. NCBI BLAST search showed that they shared identities of 94-95% to genome of Tomato yellow leaf curl China virus (TYLCCNV). A pair of virus-specific primers, TYLCCNVFa (5'-TGRTAGGWACYTGAGTAGAGTGG-3') and TYLCCNVRa (5'-TCRTCCATCCATATCTTCCCAA-3'), was then designed and used to amplify the remaining sequence of the genome. The full-length genomic sequence of one isolate, YWSh03, was determined to be 2,733 nucleotides (KJ477327). Sequence comparison showed that the genome of YWSh03 was 96.2% identical to that of TYLCCNV-[G102] (AM050555). PCR using primers Beta01 and Beta02 (2) was also tested for the association of satellite DNAß with this virus. A DNA fragment was obtained from isolate YWSh03, and its sequence was determined to be 1,336 bp (KJ477326). This sequence is 99.9% identical to TYLCCNV-associated DNAß [Y10] (AJ421621). The results show that TYLCCNV, a virus infecting tomato, tobacco, kidney bean and various weeds (3), is also associated with the disease in P. notoginseng. To determine whether TYLCCNV might cause disease on P. notoginseng, infectious clones of TYLCCNV DNA-A and DNAß provided by Dr. Xueping Zhou (Zhejiang University, China) were used to inoculate healthy P. notoginseng plants by an Agrobacterium-mediated method. The inoculated plants showed typical symptoms of yellowing, curling and stunting, confirming TYLCCNV is the causal agent of the disease. To further investigate the distribution and incidence of the virus, 258 symptomatic P. notoginseng samples were collected from 18 fields in Wenshan, Honghe, Qujing and Kunming of Yunnan Province and tested by the TYLCCNV-specific PCR. The virus was detected in 149 samples (57.8%), indicating the infection of TYLCCNV is common. To our knowledge, this is the first report of TYLCCNV infecting P. notoginseng and the family Araliaceae.

Last Modified: 11/27/2014
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