First Report of Tomato yellow leaf curl Kanchanaburi virus Infecting Eggplant in Laos.

Abstract

Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV) is a bipartite begomovirus (genus Begomovirus, family Geminiviridae) reported to infect tomato and eggplant in Thailand and Vietnam (1,2). In April 2013, eggplant (Solanum melongena L.) plants exhibiting yellow mosaic symptoms were found in a suburb of Vientiane, Laos. Three symptomatic samples were collected. Total DNA was extracted from leaves by the CTAB method, and used as template for PCR using the degenerate primer pair AV494/CoPR (3). The PCR results suggested that the plants were infected by a begomovirus. The begomoviral genome was amplified by rolling circle amplification (RCA) with TempliPhi kit (GE Healthcare) following the manufacturer's protocol. RCA product was digested with the endonucleases BamH I, EcoR I, Hind III, Kpn I, Pst I, and Xba I, respectively. The fragments about 2.1 kbp (with Pst I digestion) and 1.5 kbp (with Xba I digestion) in size were cloned and sequenced. The sequence of the 2.1-kbp fragment showed similarity with begomovirus DNA-A component. A pair of primers for amplification of the full-length DNA-A, AF (5'-CTTCATCGTTTCTCAGCATCAT-3') and AR (5'-CACTTGCACACGATCTCTAAGA-3') were designed from the 2.1-kbp sequence. The full-length DNA-A was 2,752 nucleotides and encoded six putative ORFs (GenBank Accession No. KF218820). The sequence of the 1.5-kbp fragment shared similarity with begomoviruses DNA-B. The begomoviral circular DNA-B was amplified using the pair of primers BF (5'-GTAACAGCCGAAGTGCACG-3') and BR (5'-AATGGAGAGACACCAGTCTGCC-3') designed from the 1.5-kbp sequence. PCR yielded a product of expected size (~1.4 kbp). The full-length DNA-B sequence was obtained by assembling the two sequences. The DNA-B was 2,734 nucleotides and encoded two putative ORFs (GenBank Accession No. KF218821). The sequences of DNA-A and DNA-B of isolate Laos shared the highest nucleotide sequences identities at 99.0% and 98.0% with those of TYLCKaV-[TH:Kan 1:01] (AF511529), and [TH:Kan 2:Egg:01] (AF511527), respectively. The results indicated that the virus associated with eggplant yellow mosaic disease was an isolate of TYLCKaV. To our knowledge, this is the first report of this begomovirus in Laos. Our results indicate that this virus may be spreading in Southeast Asia and scientists there should be aware of this virus when developing begomovirus-resistant varieties of tomato or eggplant.