First report of Euphorbia leaf curl virus in passion fruits in South Korea and its natural occurrence in papaya

Abstract

Euphorbia leaf curl virus (EuLCV), belonging to the genus Begomovirus, has been identified in poinsettia (Euphorbia pulcherrima) and passion fruit (Passiflora edulis) plants cultivated in China and Taiwan (Cheng et al. 2014 Wu et al. 2011). In 2014, symptomatic passion fruit plants showing yellow spotting and curling of leaves were first identified from tropical crop farms of three different regions (Goheung, Haenam, and Damyang) located in the southern part of the Korean peninsula. Viral DNA of each sample (6 samples from 3 regions) was isolated (Viral Gene-spin Viral DNA/RNA Extraction Kit, iNtRON Biotech., Seongnam, Republic of Korea) and amplified through rolling circle amplification (TempliPhi Amplification Kit, GE Healthcare Life Sci., Uppsala, Sweden) following manufacturer’s instructions. Amplified DNA was digested by the restriction enzyme NheI (TaKaRa Bio, Shiga, Japan) and separated on an agarose gel. DNA fragments (2.8 kb) were purified from the gel, ligated into a pGEM-T easy vector (Promega, Madison, WI), and sequenced (Macrogen, Seoul, Republic of Korea). According to BLAST search results, the full-length genome sequence (GenBank Accession No. KT259282) of 2.8-kb DNA fragments showed 99.38% identity to the EuLCV Taiwan isolate (KC161185) and 98.47% identity to the Chinese (Shandong) isolate (KC852148). Polymerase chain reaction (PCR) using 2×Taq PCR MasterMix (Bioneer, Daejeon, Republic of Korea) with EuCVspecificprimers designed based on the viral genome sequence of EuLCV Korea isolate in this study(EuLCV-F: 5′- CAGGATCGAGCCGTGCTTAT-3′, EuLCV-R: 5′-GCCCAATACCACGGGTAACA-3′, expected size: 225 bp) was conducted with samples from randomly collected symptomatic passion fruit plants. Most of the passion fruit plants (23/24) were identified as EuLCV-infected according to PCR. Southern blot hybridization using probe DNA amplified with EuLCV-F and EuLCV-R primers also supported the conclusion that EuLCV was infectious to passion fruit plants. This is the first identification of EuLCV in passion fruit plants from South Korea. In the same tropical crop farm in Haenam, papaya (Carica papaya) plants cultivated with EuLCV-infected passion fruits showed mild virus disease symptoms like mild yellow spotting and curling of leaves. Full-length sequence of the viral genome from papaya was also confirmed to be identical to that from passion fruit (100%). Results of PCR and Southern blot hybridization with symptomatic papaya leaves (10/10) indicated that all papaya plants cultivated with EuLCV-infected passion fruit plants were also infected with EuLCV. This is the first report of EuLCV infecting papaya plants. Recently, in some regions of South Korea, tropical crops using seedlings and seeds imported from Taiwan and other Southeast Asian nations were cultivated gradually due to global warming. Because viruses and other pathogens infecting tropical crops can pass across the border with newly introduced tropical plants and they can infect other plants as yet unconfirmed as hosts, import and cultivation of newly introduced cropsshould be done carefully.