First report of eggplant mottled dwarf virus in Cucumis sativus from Hungary

In September 2025, cucumber plants (Cucumis sativus cv. HiScore) grown in a greenhouse in Ács, Hungary, exhibited severe leaf crinkling, vein yellowing, and necrosis. Affected fruits showed light green, predominantly elongated, and sunken lesions. Symptoms occurred on less than 1% of plants. Total RNA was extracted from fresh leaf and fruit tissues using the CTAB method described by Xu et al. (2004). Four RNA samples (two leaf and two fruit samples originating from two individual plants) were tested by reverse transcription polymerase chain reaction (RT-PCR) using specific primer sets targeting potyviruses (Salamon and Palkovics 2005), tobamoviruses (Kálmán et al. 2001), tomato spotted wilt virus (TSWV), and cucumber mosaic virus (CMV) (Nemes and Salánki 2020). Complementary DNA was synthesized with random hexamer primers using the RevertAid First Strand cDNA Synthesis Kit (Thermo Fisher Scientific Baltics UAB, Vilnius, Lithuania). All samples tested negative for the viruses mentioned above. Transmission electron microscopy of two leaf and two fruit dip preparations (originating from two individual plants) revealed bullet-shaped to bacilliform virions approximately 212–250 x 76–83 nm in size, consistent with the morphology of rhabdoviruses. Subsequently, RT-PCR was conducted using a specific primer pair (EMDV-PL1a: 5’-ATGGGGGCATCCTATCATAGA-3’ and EMDV-PL2b: 5’-GCGACGTACTTTATATCACACACTGTCAT-3’) designed based on the RNA-dependent RNA polymerase gene (L gene) sequences of eggplant mottled dwarf virus (EMDV) (Alfaro-Fernández et al. 2024). Specific amplification products of the expected size (~1053 bp) were obtained from RNA extracts of both symptomatic leaves and fruits of cucumber plants. The nucleotide sequence of one representative amplicon was determined and deposited in the NCBI GenBank database (accession no.: PX873572). BLASTn analysis of the L1 region (a region of the L gene corresponding to nt positions 8212–9087 of the reference sequence NC₀25389) revealed nucleotide identities ranging from 85. 50 to 98. 74% with EMDV isolates available in GenBank. The Hungarian EMDV isolate showed the highest nucleotide identity with the Italian isolate SOM-2 (HG916817) originating from eggplant. Phylogenetic analysis was performed using MEGA7 (Kumar et al. 2016). The maximum-likelihood tree reconstructed based on nucleotide sequences of the L1 region (a region of the L gene) showed that the Hungarian EMDV isolate clustered within subclade B2 together with Italian isolates. EMDV has been assigned to the species Alphanucleorhabdovirus melongenae (family Rhabdoviridae) and infects several economically important vegetable crops, including eggplant, tomato, potato, pepper, and cucumber, as well as numerous ornamental and wild hosts. The virus is transmitted by leafhoppers. It was first detected in Italy in 1969 and is currently widespread throughout the Mediterranean basin, with reports from numerous European, African, and Asian countries (Martelli et al. 2011). Although the incidence of EMDV infection was extremely low in the investigated greenhouse and no leafhopper vectors were observed, severe outbreaks may occur in the presence of competent insect vectors. To our knowledge, this study represents the first report of eggplant mottled dwarf virus occurrence on cucumber in Hungary.