Year: 2025
Type: article
Abstract: Severe yellow-green mosaic virus-like symptoms were observed on ten Veltheimia bracteata ’Lemon Flame’ plants at a garden center in Kecskemét, Hungary, in 2019 (Suppl. Fig. 1). Symptom incidence reached 100%. Three symptomatic plants were sampled for further analysis. Potyvirus-specific ACP-ELISA was performed on 100 mg leaf tissue from each plant in duplicates using the MAb PTY1 antibody (Jordan and Hammond 1991; Agdia EMEA, France) following the manufacturer’s instructions. PVY served as positive control, while Chenopodium murale plants grown in a vector-free chamber were used as negative controls. After 30 minutes of incubation at 37°C with 1 mg/ml pNPP substrate, absorbance was measured at 405 nm using a Multiskan MS ELISA reader (Labsystem, Finland). Blank-corrected values were considered positive when at least threefold higher than the mean absorbance values of the negative controls. All tested samples were ELISA-positive (negative: 0.006, 0.008; samples: 781-1: 1.233, 1.249; 781-2: 1.247, 1.251; 781-3: 1.111, 1.207;) indicating potyvirus infection. PCR test was performed on a PTC-150 MiniCycler (MJ Research Inc., USA). Potyvirus-specific RT-PCR was carried out with poty7941 and polyT2 primers (Salamon and Palkovics 2005). Specific PCR products with an expected size of about 1600 bp were isolated from the gel, ligated into pGEM-T Easy vector (Promega GmbH, Germany) and transformed into E. coli DH5α cells. Inserts were Sanger-sequenced using M13 forward and reverse primers. ClustalW alignment showed 100% identity among the tree sequences confirming infection by the same virus isolate. Because the sequences were identical, only isolate 781-1 was deposited in NCBI GenBank (OR425164). MegaBLAST analysis of the complete coat protein (CP) region revealed 99.00% nucleotide identity with Veltheimia mosaic virus (VelMV, EU042763) isolated from Eucomis punctata and 92.01% with VelMV (EF203686) from Veltheimia bracteata ’Lemon Flame’ both reported from the Netherlands, indicating that the sampled plants were infected with VelMV. To rule out complex infection, all samples were RT-PCR tested for Nepovirus subgroup A (Digiaro et al. 2007) and Orthotospovirus tomatomaculae (Nemes and Salánki 2020), all yielding negative results. Koch’s postulates were fulfilled using asymptomatic Veltheimia bracteata plants previously confirmed virus-free by RT-PCR and inoculated via the bulb-grafting method (Cayley 1928). Three RT-PCR negative plants served as controls (Suppl. Fig. 2) and were grafted with material from other negative plants. In the following season, plants inoculated with grafts from symptomatic individuals developed severe yellow-green mosaic, narrower and more undulated leaves, and stunting. The symptoms on the artificially inoculated plants matched those of the originally sampled ones, confirming that reduced stature and narrower, more undulated leaves are also characteristic of VelMV infection. Only symptomatic inoculated plants tested potyvirus-positive by RT-PCR and direct sequencing of the PCR products showed 100% identity on the CP region of the original VelMV isolate, verifying successful graft transmission. VelMV has previously been reported from New Zealand (Pearson et al. 2009) and from the Netherlands (Pham et al. 2011). To our knowledge, this is the first report of VelMV from Hungary.
Source: Plant Disease
Language: English
Topic: Plant Virus Research Studies
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: bronze
Funder: Hungarian Research Network
OpenAlex ID: W7117371377