First Report of Wild Tomato Mosaic Virus Infecting <i>Cyphomandra betacea</i> in China

Tamarillo (Cyphomandra betacea Sendtn.), a perennial small tree or shrub belonging to the genus Solanum (Solanaceae), is native to the South American Andes and is cultivated in regions including Yunnan and Taiwan, China. In May 2025, ten tamarillo samples exhibited symptoms of leaf mosaic and uneven fruit coloring （Figure S1）collected from Malipo City, Yunnan Province. To investigate potential viral infections, total RNA was extracted from two pooled samples (each pool comprising five individual samples) and subjected to high-throughput transcriptome sequencing (HTS) using the Illumina HiSeq platform. Raw RNA sequencing reads were analyzed using CLC Genomics Workbench 12 (Qiagen). De novo assembly generated 37,913 and 39,073 contigs, respectively. Subsequent BLASTN analysis identified 3 E-Value 0 contigs were obtained from BLASTN and 1 of these matched with wild tomato mosaic virus (WTMV). To confirm the presence of this virus, virus-specific primer pairs were designed based on the HTS-derived contig sequences. This primer pairs (WTMV-cp-f: 5′-TCAGGGGAGACCGTTGATGC-3′, WTMV-cp-r: 5′-GACGCCCCTAACACCAAGCA-3′) were employed in RT-PCR assays targeting each viral sample. RT-PCR using WTMV-specific primers detected the virus in 8 out of the 10 tamarillo samples, yielding the expected coat protein (CP) gene fragment (813 bp). Amplification products of the expected sizes were confirmed by Sanger sequencing. WTMV, a member of the genus Potyvirus, is known to infect tobacco, tomato , chili pepper, and black nightshade (Du et al., 2014; Zhang et al., 2019; Hu et al., 2021). Initially reported infecting wild tomato in Vietnam (Ha et al., 2008), WTMV has recently become widespread in Yunnan Province, China. To further characterize the WTMV isolate infecting tamarillo, the complete viral genome (9,680 nt; GenBank accession no. PV856160) was amplified by RT-PCR using specific primers. The amplified fragments were cloned into the pEASY-Blunt Zero vector (TransGen Biotech) and sequenced. Sequence analysis revealed that the WTMV CP amino acid sequence shared 99.6% identity, and the complete genome shared 92.9% nucleotide sequence identity, with a previously reported WTMV tobacco isolate (OP169002). To our knowledge, this is the first report of WTMV infect tamarillo plants in China.