Genetic Loci of Plant Pathogenic Dickeya solani IPO 2222 Expressed in Contact with Weed-Host Bittersweet Nightshade (Solanum dulcamara L.) Plants.

Dickeya solani, belonging to the Soft Rot Pectobacteriaceae, are aggressive necrotrophs, exhibiting both a wide geographic distribution and a wide host range that includes many angiosperm orders, both dicot and monocot plants, cultivated under all climatic conditions. Little is known about the infection strategies D. solani employs to infect hosts other than potato (Solanum tuberosum L.). Our earlier study identified D. solani Tn5 mutants induced exclusively by the presence of the weed host S. dulcamara. The current study assessed the identity and virulence contribution of the selected genes mutated by the Tn5 insertions and induced by the presence of S. dulcamara. These genes encode proteins with functions linked to polyketide antibiotics and polysaccharide synthesis, membrane transport, stress response, and sugar and amino acid metabolism. Eight of these genes, encoding UvrY (GacA), tRNA guanosine transglycosylase Tgt, LPS-related WbeA, capsular biosynthesis protein VpsM, DltB alanine export protein, glycosyltransferase, putative transcription regulator YheO/PAS domain-containing protein, and a hypothetical protein, were required for virulence on S. dulcamara plants. The implications of D. solani interaction with a weed host, S. dulcamara, are discussed.

Involvement of UV-C-induced genomic instability in stimulation рlant long-term protective reactions.

The study of the mechanisms affecting single stress factor impact on long-term metabolic rearrangements is necessary for understanding the principles of plant protective reactions. The objective of the study was to assess the involvement of UV-C-induced genomic instability in induction рlant long-term protective reactions. The study was carried out on two genotypes of chamomile, Perlyna Lisostepu (PL) variety and its mutant, using UV-C pre-sowing seed radiation exposure at dose levels 5-15 kJ/m2. Multiple DNA damages under different exposure doses were studied on plant tissues during the flowering stage using - ISSR-RAPD DNA marker PCR. In the cluster analysis of changes within the amplicon spectra as an integral group the Jacquard similarity index was used. The results of the study suggest that genomic instability is a link between the direct effects of UV-C exposure and stimulation of metabolic rearrangements at the final stages of ontogeny. A hypothetical scheme for the transformation of primary UV-C DNA damage into long-term maintenance of genomic instability signs has been proposed.

Spontaneous mutations in hlyD and tuf genes result in resistance of Dickeya solani IPO 2222 to phage ϕD5 but cause decreased bacterial fitness and virulence in planta.

Lytic bacteriophages able to infect and kill Dickeya spp. can be readily isolated from virtually all Dickeya spp. containing environments, yet little is known about the selective pressure those viruses exert on their hosts. Two spontaneous D. solani IPO 2222 mutants (0.8% of all obtained mutants), DsR34 and DsR207, resistant to infection caused by lytic phage vB_Dsol_D5 (ΦD5) were identified in this study that expressed a reduced ability to macerate potato tuber tissues compared to the wild-type, phage-susceptible D. solani IPO 2222 strain. Genome sequencing revealed that genes encoding: secretion protein HlyD (in mutant DsR34) and elongation factor Tu (EF-Tu) (in mutant DsR207) were altered in these strains. These mutations impacted the DsR34 and DsR207 proteomes. Features essential for the ecological success of these mutants in a plant environment, including their ability to use various carbon and nitrogen sources, production of plant cell wall degrading enzymes, ability to form biofilms, siderophore production, swimming and swarming motility and virulence in planta were assessed. Compared to the wild-type strain, D. solani IPO 2222, mutants DsR34 and DsR207 had a reduced ability to macerate chicory leaves and to colonize and cause symptoms in growing potato plants.

Relationship of radiation-induced genomic instability and antioxidant production in the chamomile plant.

PURPOSE: To verify the hypothesis about the preservation of signs of radiation-induced genomic instability at the flowering stage of the chamomile plant after pre-sowing seed irradiation, the interaction of dose-dependent changes in the level of DNA damage and stimulation of antioxidant production. MATERIALS AND METHODS: The study was carried out on two genotypes of chamomile, Perlyna Lisostepu variety and its mutant, using pre-sowing seed radiation exposure at dose levels 5-15 Gy. Studies of the rearrangement of the primary DNA structure of under different doses were studied on plant tissues at the flowering stage using - ISSR and RAPD DNA markers. Dose-dependent changes relative to the control of the amplicons' spectra were analyzed using the Jacquard similarity index. Antioxidants such as flavonoids and phenols were isolated from pharmaceutical raw materials (inflorescences) using traditional methods. RESULTS: Preservation of multiple DNA damages at the stage of plant flowering under pre-sowing seed irradiation at low doses was confirmed. It was found that the largest rearrangements of the primary DNA structure of both genotypes, manifested in reduced similarity with the control spectra of amplicons, were observed under irradiation dose levels 5-10 Gy. There was a tendency to approach this indicator to the control under 15 Gy dose, which means increasing efficiency of the reparative processes. The relationship between the polymorphism of the primary structure of DNA by ISSR-RAPD-markers in different genotypes and the nature of its rearrangement under radiation exposure was shown. Dose dependences of changes in the specific content of antioxidants were non-monotonic with a maximum at 5-10 Gy. CONCLUSIONS: Comparison of dose dependences of changes in the coefficient of similarity of the spectrum of amplicons between irradiated and control variants with nonmonotonic dose curves in the specific content of antioxidants allowed to suggest that there was the antioxidant protection stimulation under the doses corresponding to low efficiency of repair processes. The decrease in the specific content of antioxidants followed the restoration of the genetic material normal state. The interpretation of the identified phenomenon has been based on both known connection between the effects of genomic instability and the increasing yield of the reactive oxygen species and general principles of antioxidant protection.

Effects of genomic instability in populations of Drosophila melanogaster from regions of Ukraine with different impact of radiation factors.

PURPOSE: To investigate differences in the gonadal dysgenesis frequency as one of the indicators of genome instability through natural populations of Drosophіla melanogaster, selected from Ukrainian regions with different radiation impacts. Follow-up study of the dynamics of this indicator under chronic exposure in laboratory conditions for 10 generations. MATERIALS AND METHODS: The study was conducted in two stages. The first one included trapping of insects in regions with different radiation loads with subsequent assessment of both the time of maturation and the index of the gonadal dysgenesis through the first (F1) generation, obtained in laboratory conditions. At the second stage, the dynamics of this indicator were investigated for the F1-descendants of each ten consequent generations, which were developed under laboratory conditions both with and without additional gamma-exposure with different characteristics of the dose rate 1.2 × 10-8, 0.3 × 10-8 and 0.12 × 10-8 Gy/sec. RESULTS: Differences in the gonadal dysgenesis frequency as one of the indicators of genome instability were revealed in F1-descendants of natural populations of Drosophіla melanogaster, selected from regions of different radiation impact. Under conditions of additional low rate chronic irradiation in laboratory conditions for 10 generations, significant differences in changes in the level and dynamics of this indicator were established depending on the accumulated dose of Drosophila populations from the city of Netishyn (Khmelnytskyi NPP) and Magarach city. There were no signs of adaptation. CONCLUSIONS: The discrepancy between the real and expected biological effects has reflected the difference in the intensity of the radiation background, which was traditionally determined by the gamma-emitters and did not take into account the wide range of other genotoxic elements from nuclear power emissions. A complex, non-monotonic type of frequency dynamics of gonadal dysgenesis could be determined by the interaction of radiation damage, protection and recovery.

Epigenetic factors of individual radiosensitivity and adaptive capacity.

Purpose: Studying the relationship between epigenetic variability with different individual radiosensitivity and adaptive capacity.Material and method: Using a simple and convenient experimental model - maize seedlings with different germination terms and epigenetic patterns - the hypothesis was tested that homogeneous genetically but epigenetic different organisms have different radiosensitivity and radioadaptive capacity. Differences in the DNA methylation profiles of individual subpopulations of seedlings were used as a marker of epigenetic differences and the yield of chromosomal aberration was used as an indicator of DNA vulnerability and its changes under different UV-C irradiation modes. In two series of experiments involving а UV-C acute single and exposure according to the scheme 'adaptive - challenging', the investigation of possible biological importance of epigenetic polymorphism has been performed. The study used a cytogenetic analysis of the yield of chromosomal aberrations and restriction analysis followed by ITS-ISSR- PCR.Results: Significant differences have been established in chromosome aberration yield and DNA methylation profile in control and under UV-C exposure for seedlings of subpopulations differing in time of germination. The differences in the DNA methylation profiles and the yield of chromosomal aberrations in the control subpopulations of seedlings of different germination term indicate the influence of the DNA methylation profile on DNA damage by regular metabolic factors, such as thermal vibrations or reactive oxygen species (ROS). This phenomenon can be explained with different chromatin conformation determining structural or 'passive' resistance, which provides different DNA availability to damage. Methylation switching into de novo under different mode radiation exposure could become a marker of gene expression changes due to induced repair and protecting.Conclusions: The obtained data indicate the importance of epigenetic factors in determining the radio-resistance and adaptive capacity of organisms. It points out that the epigenetic mechanisms that determine the choice of the metabolic pattern also contribute to the individual radiosensitivity and adaptive capacity of the organisms. This contribution is determined by two ways. First, the DNA methylation profile affects the initial damage processes and secondly, the type of methylation switching into de novo is associated with the further development of protection and repair processes.