
First Report of Passiflora Latent Virus Infecting Passion Fruit (Passiflora edulis) in South Korea
- M.-K. Choi1
- H.-J. Ju2 †
- 1Division of Agricultural Environment, Jeollabuk-do Agricultural Research and Extension Services, Iksan 54591, South Korea
- 2Department of Agricultural Biology, Jeonbuk National University, Jeonju 54896, South Korea
Passion fruit (Passiflora edulis) viral diseases caused by Papaya leaf curl Guangdong virus, Cucumber mosaic virus, East Asian Passiflora virus, and Euphorbia leaf curl virus have been reported in South Korea (Joa et al. 2018; Kim et al. 2018). In June 2021, virus-like symptoms, for example, mosaic pattern, curling, chlorosis, and deformation, were observed on leaves and fruits of greenhouse-grown P. edulis in Iksan, South Korea, with disease incidence greater than 2% (300 plants: 8 symptomatic plants and 292 asymptomatic plants). Total RNA was extracted from a pooled sample of symptomatic leaves of an individual P. edulis plant using the RNeasy Plant Mini Kit (Qiagen, Germany), and a transcriptome library was generated using the TruSeq Stranded Total RNA LT Sample Prep Kit (Illumina, San Diego, CA). Next-generation sequencing (NGS) was performed using the Illumina NovaSeq 6000 system (Macrogen, Korea). De novo assembly of the resulting 121,154,740 reads was performed using Trinity (Grabherr et al. 2011). A total of 70,895 contigs (>200 bp) were assembled and annotated against the NCBI viral genome database using BLASTn (ver. 2.12.0). One 827-nt contig was annotated as Milk vetch dwarf virus, a member of the genus Nanovirus in the family Nanoviridae (Bangladesh isolate, accession no. LC094159, 96.0% nucleotide identity), and the other 3,639-nt contig corresponded to Passiflora latent virus, a member of the genus Carlavirus in the family Betaflexiviridae (Israel isolate, accession no. DQ455582, 90.0% nucleotide identity). For further confirmation, total RNA was isolated from symptomatic leaves of the same P. edulis used for NGS analysis using a Viral Gene-spin DNA/RNA extraction kit (iNtRON Biotechnology, Seongnam, Korea), and reverse-transcription polymerase chain reaction (RT-PCR) was performed using specific primers: PLV-F/R (5′-GTGCCCACCGAACATGTTACCTC-3′/5′-CCATGCACTTGGAATGCTTACCC-3′) targeting the coat protein region of PLV, MVDV-M-F/R (5′-CTAGTCAGCCATCCAATGGTG-3′/5′-GTGCAGGGTTTGATTGTCTGC-3′) targeting the movement protein region, and MVDV-S-F/R (5′-GGATTTTAATACGCGTGGACGATC-3′/5′-AACGGCTATAAGTCACTCCGTAC-3′) targeting the coat protein region of milk vetch dwarf virus (MVDV). An expected PCR product of 518 bp corresponding to Passiflora latent virus (PLV) was amplified, while MVDV was not detected. The amplicon was directly sequenced, and its nucleotide sequence was deposited in GenBank (accession no. OK274270). A BLASTn analysis showed that the nucleotide sequence of the PCR product shared 93.0 and 96.2% identity with PLV isolates from Israel (MH379331) and Germany (MT723990), respectively. In addition, six passion fruit leaves and two fruit samples with PLV-like symptoms were collected from a total of eight plants grown in the greenhouse in Iksan for RT-PCR analysis, and six samples tested positive for PLV. However, PLV was not detected in one leaf and one fruit among all samples. Mechanical sap inoculation was conducted using extracts of systemic leaves as inoculum on P. edulis and the indicator plants Chenopodium quinoa, Nicotiana benthamiana, N. glutinosa, and N. tabacum. In P. edulis, vein chlorosis and yellowing on systemic leaves were observed 20 days postinoculation (dpi). Necrotic local lesions were observed on inoculated leaves of N. benthamiana and N. glutinosa at 15 dpi, and PLV infection was confirmed by the RT-PCR assay in symptomatic leaf tissue. This study aimed to determine whether commercially grown passion fruit in the southern part of South Korea could be infected with and potentially spread PLV. Whereas PLV was asymptomatic in persimmon (Diospyros kaki) in South Korea, no pathogenicity testing in passion fruit was reported (Cho et al. 2021). Here, we have shown the natural infection of passion fruit with PLV in South Korea for the first time and associated infection with obvious symptoms. This suggests a need to evaluate potential losses in passion fruit and the selection of healthy propagation material.
The author(s) declare no conflict of interest.
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Funding: This research was carried out with the support of Jeollabuk-do Agricultural Research and Extension Services, South Korea, Research Program 2021.
The author(s) declare no conflict of interest.