First Report of Pepper Vein Yellows Virus Infecting Pepino ( Solanum muricatum ) in China

Pepino (Solanum muricatum), belonging to the family Solanaceae, is a perennial semi-woody herbaceous plant (Song et al. 2022) with significant economic value. However, in recent years, pepino has been threatened by various viral diseases. Viruses reported to infect pepino include Tobacco mosaic virus (TMV), Cucumber mosaic virus (CMV), Tomato mosaic virus (ToMV), Potato virus M (PVM), and Potato virus Y (PVY). These infections cause yield reduction and poor fruit quality, resulting in substantial economic losses to farmers. Pepper vein yellows virus (PeVYV), a member of the genus Polerovirus, is primarily transmitted by aphids in a non-propagative manner. Its natural hosts are mainly solanaceous plants, with pepper (Capsicum annuum) being the primary host. Infections have been reported globally in countries such as Spain, China, India, and Thailand (Zhao et al. 2021). In 2016, the first natural infection in tobacco (Nicotiana tabacum) by PeVYV was reported in Guizhou, China, causing interveinal yellowing and leaf crumpling symptoms in affected plants. During virus surveys in Mali and Benin, Africa, PeVYV was found infecting eggplant (Solanum melongena) (Wang et al.2016). Records from Spain and other regions also indicate that PeVYV infects black nightshade (Solanum nigrum) (Liu et al. 2019). As pepino (Solanum muricatum) is also a solanaceous plant, it is theoretically susceptible to solanaceous-infecting viruses. However, based on current literature and research, there are no public reports confirming that pepper vein yellows virus (PeVYV) can infect pepino (Solanum muricatum). In May 2023, pepino plants exhibiting leaf yellowing symptoms were observed at a plantation in Shilin County, Kunming City, Yunnan Province, China. Approximately 50% of the 100 plants inspected at the site showed symptoms of vein yellowing and mosaic mottling. To identify the causative virus, five symptomatic leaf samples from infected pepino plants collected in Shilin, Kunming were tested using a PeVYV-specific ELISA kit, with healthy pepino leaves serving as negative controls. The ELISA results showed that all samples tested were positive for PeVYV. To further confirm the presence of PeVYV in pepino, total RNA was extracted from at least one selected sample and subjected to RT-PCR using specific primers A 966-bp fragment, consistent with the expected size for PeVYV-YNs, was amplified from pepino samples. Sequencing yielded an 822-bp sequence. BLAST analysis revealed that PeVYV-YNs shared 92.13% and 91.92% nucleotide sequence identity with isolates Ca (MK931185) and YN (MT188667), respectively. The full genome sequence was obtained by RACE amplification. The isolate's genome is 5,988 nt in length (GenBank accession: OR906336) and exhibits a typical PeVYV genome structure. Phylogenetic analysis indicated that it forms a distinct branch, with nucleotide sequence similarity ranging from 79.7% to 98.4% compared to known isolates. In summary, while PeVYV infection and detection in pepper have been extensively studied, no prior reports of its infection in pepino exist. This study, by combining ELISA and RT-PCR with specific primers, demonstrates the natural infection of pepino by the PeVYV-YNs isolate. To our knowledge, this is the first report of pepper vein yellows virus infecting pepino. These findings provide a crucial basis for the prevention and control of viral diseases in pepino.