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First Report of Tobacco Mosaic Virus Infecting Bidens pilosa in China

    Affiliations
    Authors and Affiliations
    • Peng Chen
    • Ping-Xiu Lan
    • Fan Li
    1. State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming 650201, China

    Bidens pilosa is an annual weed in the family Asteraceae and is widely distributed in tropical and subtropical regions worldwide. It is also a natural host for at least five viruses, namely, tomato spotted wilt orthotospovirus, tomato zonate spot orthotospovirus, pepper chlorotic spot orthotospovirus, Bidens mottle virus, and Bidens mosaic virus; therefore, it serves as a virus reservoir for various field crops (Wang et al. 2009; Xu et al. 2022; Yin et al. 2013). In August 2021, plants of B. pilosa displaying symptoms of chlorosis, mosaic, and necrosis were observed in the surroundings of a tobacco field in Kunming, Yunnan Province, China. Leaf samples were collected from four diseased B. pilosa plants, and total nucleic acids were extracted using a cetyltrimethylammonium bromide–based method (Li et al. 2008). RT-PCR was carried out using virus-specific primers designed for the aforementioned five viruses as well as tobacco mosaic virus (TMV). The results indicated that none of the four samples tested positive for the five viruses, except for one sample, which produced an amplicon of the expected size (700 bp) with the TMV-specific primer pair TMVF (5′-CGGTCAGTGCCGAACAAGAA-3′) and TMVR (5′-TACGTGCCTGCGGATGTATATG-3′). Cloning and sequencing the amplicon revealed a 717-nt fragment (accession no. OR136480) in the core cp region of TMV, which showed the highest nucleotide sequence identity of 99.6% with other TMV isolates (HE818450) in GenBank. TMV infection was also verified by the dot enzyme-linked immunosorbent assay using the antisera of TMV (Beijing Green Castle Agricultural Technology). To further confirm the TMV infection in B. pilosa plants, a TMV infectious clone (kindly provided by Dr. Fei Yan at Ningbo University, China) was inoculated into 12 healthy 3-week-old B. pilosa seedlings using Agrobacterium-mediated delivery. None of the inoculated B. pilosa plants exhibited distinct symptoms even 30 days after inoculation. Nevertheless, RT-PCR and Sanger sequencing results revealed that two of the inoculated B. pilosa plants were infected by TMV. The above results collectively indicate that TMV can infect B. pilosa under both natural and artificial conditions. However, it is possible that the symptoms observed on the diseased B. pilosa plants in the field may not be solely attributed to TMV but rather to the coinfection of TMV with other unidentified viruses, which were not characterized in this study. TMV is considered one of the economically significant pathogens affecting crops such as tobacco (Nicotiana tabacum), pepper (Capsicum spp.), and tomato (Solanum lycopersicum). It is highly contagious and can be transmitted through various means, including seeds, soil, and agricultural practice. B. pilosa is considered one of the most significant alien invasive weeds in China, mainly owing to its robust reproductive capacity. Furthermore, B. pilosa has the potential to act as a reservoir for various viruses that may affect field crops. The presence of TMV on B. pilosa plants may enhance the transmission efficiency of the virus in the field. Although TMV does not induce noticeable symptoms in B. pilosa, its presence on these plants could potentially increase the transmission efficiency of the virus in the field, posing a significant risk to field crops. Therefore, effective weed management and the diligent monitoring of TMV in B. pilosa should be recognized as essential sanitary practices for controlling viral diseases in field crops. To the best of our knowledge, this is the first report of TMV infecting B. pilosa in China.

    The author(s) declare no conflict of interest.

    References:

    Funding: This study was funded by the National Key R&D Program of China (2022YFD1400700 and 2022YFD1401200).

    The author(s) declare no conflict of interest.