Members of Ralstonia solanacearum species complex (RSSC) are causal agents of vascular wilt disease in more than 450 crop species, including solanaceous plants such as potatoes, tomatoes, bell pepper, eggplant, etc. These phytopathogens cause serious yield loss mostly in solanaceous crops which are grown in tropical, subtropical, and temperate regions of the world. Yield losses comprise 80%–100% in potato, up to 91% for tomato, 10%–30% in tobacco, 33%–90% in banana, and reduce crop productivity and yield. PCR-methods are specific, sensitive and cost-effective approaches for the detection and identification of RSSC members. The objective of this study was to compare specificity of routinely used primer mix for PCR RSSC detection with the newly developed pairs of species-specific primers for ease of use diagnostics in a laboratory. Materials and Methods. The conserved genomic regions of the 16S rRNA sequences of R. solanacearum, R. pseudosolanacearum, and R. syzygii were selected for the design of primers for this study. Newly created primer species specificity was tested in PCR using the DNA of the two targets and 13 non-target strains of bacteria. Results. Three pairs of newly created primers Rs-28(F)/Rs-193(R), Rs-28(F)/OLI-160(R), Rs28(F)/OLI248(R) produced single specific fragments for bacterial strains of Ralstonia solanacearum: 166 bp, 132 bp, and 220 bp. products respectively. No PCR products were obtained during amplification with the negative control or non-target DNA templates from other bacterial species. Conclusion. Designed primers can be used for the development of PCR system for the qualitative and quantitative detection of RSSC members.

Aim. To investigate the prevalence of causative agents of ring rot and soft rot in the potato harvest by the DAS ELISA method. Materials and methods. Samples of the potato harvest from Ternopil, Zhytomyr, Kyiv, Cherkasy, Dnipropetrovsk, Donetsk, Mykolaiv, Odesa, and Kherson regions were used in the study. The detection of bacterial agents was conducted by enzyme-linked immunosorbent assay using commercial test systems LOEWE® Standard Complete Kit (Germany). Results. The highest percentage of affected potatoes was registered in the Donetsk region: 11.1% – by the Clavibacter seedonicus, 31.0% – by the Pectobacterium atrosepticum, and 8.9% – by both bacteria. The causative agent of soft rot was detected twice as often as a causative agent of ring rot in tuber samples from all regions, except the Ternopil region, where the predominance of Clavibacter sepedonicus was revealed. In addition to the Donetsk region, a high prevalence of the causative agent of soft rot was found in the potato harvest from Kyiv (10.2%) and Odesa (10.0%) regions, the highest abundance of the causative agent of ring rot was detected in the Ternopil region. The mixed bacterial infection of potato tubers was diagnosed in 6 areas, and the highest rate was detected in the Donetsk region. Conclusion. The analysis of the distribution of ring rot pathogen Clavibacter sepedonicus and soft rot pathogen Pectobacterium atrocepticum in the potato crop shows the presence of research pathogens in all studied regions. It was discovered the dominance of the representative of pectolytic bacteria in all regions except Ternopil, where the distribution of Clavibacter sepedonicus, the causative agent of ring rot, was dominated. High rates of spread of the studied pathogens were associated with increased local average annual precipitation, as well as with increased annual amplitude of this indicator.