Pepino mosaic virus (PepMV) is a mechanically-transmitted tomato pathogen of importance worldwide. Interactions between the PepMV coat protein and triple gene block protein (TGBp1) with the host heat shock cognate protein 70 and catalase 1 (CAT1), respectively, have been previously reported by our lab. In this study, a novel tomato interactor (SlTXND9) was shown to bind the PepMV TGBp1 in yeast-two-hybrid screening, in vitro pull-down and bimolecular fluorescent complementation (BiFC) assays. SlTXND9 possesses part of the conserved thioredoxin (TRX) active site sequence (W__PC vs. WCXPC), and TXND9 orthologues cluster within the TRX phylogenetic superfamily closest to phosducin-like protein-3. In PepMV-infected and healthy Nicotiana benthamiana plants, NbTXND9 mRNA levels were comparable, and expression levels remained stable in both local and systemic leaves for 10 days post inoculation (dpi), as was also the case for catalase 1 (CAT1). To localize the TXND9 in plant cells, a polyclonal antiserum was produced. Purified α-SlTXND9 immunoglobulin (IgG) consistently detected a set of three protein bands in the range of 27–35 kDa, in the 1000 and 30,000 g pellets, and the soluble fraction of extracts of healthy and PepMV-infected N. benthamiana leaves, but not in the cell wall. These bands likely consist of the homologous protein NbTXND9 and its post-translationally modified derivatives. On electron microscopy, immuno-gold labelling of ultrathin sections of PepMV-infected N. benthamiana leaves using α-SlTXND9 IgG revealed particle accumulation close to plasmodesmata, suggesting a role in virus movement. Taken together, this study highlights a novel tomato-PepMV protein interaction and provides data on its localization in planta. Currently, studies focusing on the biological function of this interaction during PepMV infection are in progress.

Watermelon mosaic virus (WMV) is a potyvirus and a member of the bean common mosaic virus (BCMV) lineage. It is one of the most economically important viral pathogens of cucurbits worldwide and was first reported in the Czech Republic in 2011 from serological surveys (2005–2011). In this study, we confirmed this identification by determining the complete coding regions of five Czech WMV isolates using high‐throughput sequencing and Sanger sequencing (MW188031; OP585149–OP585152), together with the coat protein (CP) genes of 26 additional isolates. Phylogenies were made from these and more than 128 genomes or 128 CP genes from GenBank. They showed that the Czech isolates were most closely related to other European isolates, but, surprisingly, 96.2% of the genomes were recombinant. The nonrecombinant sequences mostly came from basal isolates, all originating from China, and some from unusual hosts (Ailanthus altissima, Alcea rosea and Panax ginseng). The complete WMV genomes form three phylogenetic clades, two of them small and basal, and the third includes all other isolates. Comparative dating suggests that the basal Chinese isolates are descendants of a potyvirus population infecting various dicotyledonous plant species in China at least 2000 years ago. WMV became a crop pathogen around 1000 years ago, a few years after watermelon was taken to northern China and first grown as a crop during the Five Dynasties (907–960 ce).

Prunus necrotic ringspot virus (PNRSV) and cherry virus A (CVA) are two viruses that mainly infect plants of the genus Prunus. Full-length sequences of these two viruses, collected in the Czech Republic from Prunus cerasifera plants, were obtained via HTS sequencing. Phylogenetic analyses based on the NJ method and Splitstree tools showed that the Czech PNRSV isolate (ON088600-ON088602) is a divergent isolate from other molecular groups, sharing less than 97% pairwise nucleotide identity with members of other groups. The Czech CVA isolate (ON088603) belonged to molecular subgroup III-2, clustered with isolates from non-cherry hosts, and shared the highest pairwise nucleotide identity (99.7%) with an isolate of Australian origin.