Although wheat streak mosaic virus (WSMV) is a well-known pathogen inducing significant crop losses and endangering wheat production worldwide, the recent discovery of High Plains wheat mosaic virus (HPWMoV) in Ukraine raises questions on the co-existence of these two viruses having a similar host range and the same mite vector. Here we report on the screening of winter wheat industrial plantings in several important regions of Ukraine for WSMV and HPWMoV. WSMV was identified in an extremely high number of symptomatic plants (>85%) as compared to HPWMoV detected in 40% of wheat samples. Importantly, the preferred mode of HPWMoV circulation in Ukraine was mixed infection with WSMV (>30%) as opposed to WSMV, which was typically found in monoinfection (60%). Screening wheat varieties for possible virus resistance indicated that all but one were susceptible to WSMV, whereas over 50% of the same varieties were not naturally infected with HPWMoV. Overall, phylogenetic analysis of the collected WSMV and HPWMoV isolates indicated their high identity and similarity to other known isolates of the respective viruses. Here we first characterize WSMV isolates found in winter wheat plants in mono- or mixed infection with HPWMoV, which was recently reported as a typical wheat pathogen in Ukraine.

Tomato mosaic virus (ToMV) induces highly infectious disease of vegetables, whereas use of virus-contaminated seed may lead to complete yield loss. This work was aimed at studying phylogenetic relationships of Ukrainian tomato isolates of ToMV with its known isolates by comparing nucleotide sequence of coat protein gene. ELISA, TEM, RT-PCR, sequence analysis using MEGA 5 software, and statistical methods. cDNAs of two novel Ukrainian isolates ToMV-ukr-5 and ToMV-ukr-10 corresponding to coat protein (CP) gene were sequenced and compared with other published ToMV sequences. On the constructed phylogenetic tree, ToMV isolates were grouped into two separate clusters. In addition to novel Ukrainian isolates ToMV-ukr-5 and ToMV-ukr-10, the first and larger cluster contained nearly all virus isolates used in this study with high (96-98,9 %) level of homology to Ukrainian isolates. The larger cluster was clearly separated into two subclusters: one grouping isolates with over 96,7 % identity with Ukranian isolates, and the other containing three strains and isolates with 96,1 % identity (tomato isolate SL-1, strain camellia isolated from a decorative plant, and isolate Dahlemense DSMZ PV-0135).Two novel Ukrainian isolates ToMV-ukr-5 and ToMV-ukr-10 have been isolated from tomato plants cultivated in open field conditions in different regions of Ukraine. Phylogenetic analysis confirmed high identity of Ukrainian isolates between themselves and with other published ToMV sequences. Ukrainian isolates were most homologous (>98 %) to Brazilian isolate Hemerocallis, to Chinese isolate G2, and to the following tomato isolates: AH4, Queensland, ToMV-tom and Ls-K, S14, and FERA_160205. The high level of homology was traced independently of the source of virus isolation, its plant host and their geography.

The early spring of 2024 contributed to emergence of viruses both in Ukraine and in neighboring Moldova. Already in April, wheat plants with signs of virus damage were selected in Vinnytsia and Dnipropetrovsk regions, and almost at the same time in Moldova. In May, the Wheat stripe mosaic virus (WSMV) was also discovered in Poltava. WMSV was detected in both countries, which has a significant epidemic potential, leading to a decrease in yield. In addition, in Ukraine, we continued to observe the manifestation of cold stress due to a daily temperature drop of more than 20ºC, which led to the appearance of symptoms such as purple leaves and the development of chlorotic and yellowish-brown stripes, which are very similar to viral damage. The absence of viruses in such stressed wheat plants has been conclusively proven. A reliable decrease in wheat yield was established not only under the influence of a viral infection, but also in variants with a daily temperature difference in May-June, that is, the phase of emergence into the tube and the beginning of earing.

Goal. To diagnose potato virus Y (PVY) and potato leaf roll virus (PLRV) in potato plantations and determine the impact of the pathogens on plant yield. Methods. Visual diagnosis method, double sandwich enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, morphomentric and statistic methods were carried out in this study. Results. Among the varieties studied, the most common symptom was upward leaf rolling, with some varieties exhibiting mosaics with necrosis and leaf deformation when the others show leaf rolling with necrosis. Virus identification was carried out in different potato varieties. It was found that PVY was detected in 3 varieties, PLRV was revealed in 4 varieties, mixed infection of PVY + PLRV was confirmed in 2 potato varieties, the incidence was 27.3%, 36.4% and 18.2%, respectively.It was found that among all varieties of different maturity groups, the most pronounced harmful effect of viruses on yield was observed in early varieties. Moreover, exactly PLRV infection most significantly reduced such indicators as yield (g/bush), average weight of one tuber, and average weight of one marketable tuber or mixed infection PLRV + PVY (in the case of mid-early varieties) compared to PVY mono-infection (for early, medium- and late-maturing varieties). On the other hand, the presence of PVY in plants (in mono- or coinfection with PLRV) reduced the average number of tubers per bush more than PLRV for some varieties. Conclusions. Significant yield losses observed due to PVY, PLRV and PVY + PLRV coinfection indicate the need to use virus-free seed potatoes or varieties resistant to them.