Phaseolus vulgaris alphaendornavirus-1 is frequent in bean germplasm in Slovakia and shows low molecular variability

Phaseolus vulgaris alphaendornavirus-1 (PvEV-1, family Endornaviridae) was identified by ribodepleted total RNA high-throughput sequencing in the virome of two bean plants (Phaseouls vulgaris L.) grown in a garden in western Slovakia. Two nearly complete PvEV-1 genomes (ca. 14.06 kb, named PV1 and PV2) were assembled, showing 99.9% nucleotide identity, while their nucleotide identity with the reference PvEV-1 genome (NC_039217) reached 98.4%. Two primer pairs spanning the viral helicase encoding region and sequence upstream of the RNA-dependent RNA polymerase were designed and used to confirm the presence of the virus in the original bean samples by RT-PCR. A subsequent search for PvEV-1 presence in Slovakia was focused on two groups of samples: 1) bean plants grown under open field conditions and sampled during the vegetation period and 2) bean accessions grown from seeds obtained from a Slovak and French bean germplasm collection. Based on RT-PCR results, 4 out of 15 bean samples from open fields and 12 out of 21 bean accessions from the curated germplasm collection tested PvEV-1-positive. Interestingly, sequencing of RT-PCR products revealed that all amplified isolates are identical in the two amplified genomic portion which is also identical to those of the PV1 and PV2 isolates. These results suggest a relatively high incidence of PvEV-1 in bean in Slovakia. This is the first evidence and characterization of PvEV-1 from bean plants in Europe.