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Gladioli can be affected with 15 species of viruses, which cause significant economic losses to both floriculture and agriculture. The most prevalent and harmful for gladioli are Bean yellow mosaic virus (BYMV) and Cucumber mosaic virus (CMV), circulating on the territory of Ukraine on vegetable, legume and other crops, and also Tobacco ringspot virus (TRSV), which is included into the List of regulated pests of Ukraine and is the subject to strict control. The aim of the work was to conduct testing of gladiolus plants for the presence of viral infection symptoms and to test them for the affection with the most widespread and dangerous viruses, namely: BYMV, CMV, TRSV. Visual diagnostics, enzyme-linked immunosorbent assay in DAS-ELISA modification, transmission electron microscopy method and statistical data analysis were used in this research. The results of the studies showed absence of TRSV in all tested samples. For the first time in Ukraine, it has been established that gladioli are infected by Bean yellow mosaic virus. Its circulation on gladioli has been registered in Poltava, Kyiv and Sumy regions. Gladioli were also found to be affected by CMV or mixed infection of these pathogens. Gladioli infection by BYMV and CMV in Kyiv region is 88.2% and 93.8%, in Poltava – 69.2% and 55.5%, in Sumy – 66.6% and 0%, respectively. Typical symptoms on gladiolus plants caused by CMV and BYMV isolates are leaf chlorotic stripes and flower color break, less often – spotting on the leaves and plant stunting. It has been revealed that affection of gladioli by CMV and BYMV can be asymptomatic. The diversity, nature and course of viral infections in gladioli demonstrate the relevance of further research and their monitoring in Ukraine.

Bean yellow mosaic virus (BYMV) is the one of most prevalent and harmful viruses infecting gladiolus plants worldwide. The aim of the study was to perform phylogenetic analysis of two Ukrainian BYMV isolates from gladioli grown in different regions of Ukraine and determine phylogenetic relationships of the isolates to other BYMVs. Visual diagnostics, enzyme-linked immunosorbent assay in DAS-ELISA modification, total RNA extraction, RT-PCR, phylogenetic analysis and statistical data analysis were used in this research. The results of the studies showed that gladioli of variety Pamyat’ (Poltava region, 2018) and var. Galyna Zelenobirska (Kyiv region, 2020) with symptoms of chlorotic stripes and mosaics on the leaves, flower color breaks are infected by BYMV. Fragments of the CP gene sequence of Ukrainian gladiolus isolates of bean yellow mosaic virus, named GlMP-18 (MK416160) and BYMV-Gl-SV-20 (MZ286966) were sequenced and deposited to the NCBI GenBank. Nucleotide sequences of these isolates corresponding to 578 nt of the coat protein gene (CP) located at the position 8727–9305 of the viral genome and amino acid sequences were compared with 40 known BYMV isolates/strains. Phylogenetic analysis demonstrated that GlMP-18 and BYMV-Gl-SV-20 have identity of nucleotide sequence 100% and amino acid sequence 100% with each other. Both Ukrainian isolates clustered with the Monocot group. The identity of the СР gene sequences of the two gladiolus isolates GlMP-18 and BYMV-Gl-SV-20 from geographically remote regions of the country and in different years of selection indicates a common origin of isolates and probable their distribution of planting material.

SUMMARYPlant diseases caused by bacteria are a serious problem in the cultivation and storage of agricultural products. During the last years bacteriophages have attracted increased research interest as a realistic environmentally friendly means for controlling bacterial diseases. The main objective of the study was to characterize the bacteriophages that could be used in the search for and developing the antimicrobial agents based on bacterial viruses. Four isolates of bacteriophages specific to bacteria from Pseudomonas genus were isolated from potato samples with typical symptoms of bacterial disease. These phage isolates differed in terms of the morphology of their negative colonies. Slight variation in the morphology of studied phages was observed using electron microscopy. A group of phages was identified as Podoviridae family of Caudovirales order (icosahedral head without long tail, small size -head diameter 43 ± 1 nm, tail length 1 ± 0,5 nm). To identify host range/specificity of isolated phages, we analyzed the spectrum of lytic activity against 15 strains of phytopathogenic bacteria. Our research revealed that among four phage samples three expressed lytic activity against different strains of phytopathogenic bacteria. The aforementioned data enable us to conclude that these three isolates with broad spectrum of lytic activity can be used as perspective biologic agents in control of bacteriosis. Thereby phages from our collection could be of therapeutic interest, they have the potential to be used in future prospects for phage therapy research.

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