Longan witches’ broom-associated virus (LWBaV), a member of the family Potyviridae, possesses a positive-sense single-stranded RNA genome, was first described to infect longan (Dimocarpus longan Lour. ) at an experimental greenhouse in Hanoi, Vietnam (Seo et al. 2017). Longan is a tropical fruit tree of the soapberry family (Sapindaceae) and is grown widely in Southeast Asia, including Vietnam, China, and Thailand. Litchi (Litchi chinensis Sonn. ), another economically important subtropical soapberry family tree species belonging to the family Sapindaceae, have similar environmental requirements and shares abundant habitat with Longan (Lora et al. 2018). LWBaV was detected in litchi seedlings imported from China in Gimcheon, South Korea in 2024 (Belete et al. 2025). Since litchi plants are cultivated in several provinces of China, including Guangdong, Guangxi, Fujian, Hainan and Taiwan, the region of LWBaV infecting litchi trees in China remains unclear. In December 2025, one litchi plant in the campus of Fujian Agriculture and Forestry University in Fujian, China (26°05′4. 35″N, 119°14′21. 57″E) exhibited virus disease-like symptoms, including leaf deformation, shoot proliferation, and shortened internodes. To identify the causal agent, total RNA was extracted from the symptomatic leaves with CTAB method (Wang and Stegemann, 2010). An rRNA-depleted library was constructed with the diseased litchi total RNA and subjected to high throughput sequencing in PE150 mode on an Illumina NovaSeq 6000 platform at Novogene, China, generating 50. 99 million reads. After removing low-quality reads using fastp (version 1. 0. 1) (Chen 2025), 50. 74 million reads were assembled de novo using Trinity (version 2. 15. 1) with default parameters. Contigs longer than 200 bp were used to search the NCBI non-redundant (NR) protein database using BLASTx to identify possible viral contigs. A total of 489 contigs yielded significant hits against a locally curated viral RefSeq protein database (downloaded on 18 August 2025 from NCBI (https: //www. ncbi. nlm. nih. gov/) ), with aligned regions exceeding 500 amino acids in length. Among these, a contig of 9, 429 bp exhibited notable sequence similarity to LWBaV, which is the only virus like sequence identified in the high throughput sequence data. Subsequent BLASTn analyses revealed that the obtained genomic sequence shared 96. 18% and 92. 41% nucleotide sequence identity with the isolate Gm1 (PV470486) and isolate Han1 (NC₀34835) of LWBaV, respectively. To further verify whether the plants were infected with LWBaV, we designed a primer pair, 8616F/9232R (5’-CGAGTCTTCTTTCCAATATGGAG-3’/5’GGCGGGCCACAGGATATTAATGA-3’) which was used to amplify the 617-bp fragments for the partial sequences of CP in the LWBaV genome. The amplified PCR product was cloned to plasmid and sanger sequenced. The resulting sequence shared 95. 62% and 93. 52% nucleotide homology with the LWBaV isolate Gm1 (PV470489) and isolate Han1 (NC₀34835), respectively. To our best knowledge, this is the first report of LWBaV infecting litchi in Fujian, China, extending the information on its geographical distribution. This finding also lays the foundation for the detection and management strategies of litchi virus diseases.
Tao et al. (Sun,) studied this question.