Relevance. The presented studies are aimed at obtaining new forms of tomato with a complex of genes for resistance to fungal diseases in combination with a standard type of bush and dark coloring of fruits based on marker-mediated selection.Methodology. The biological objects of the study are varieties and hybrid forms of tomato from the collection of the Michurinsky SAU. Molecular genetic analysis was performed using the following methods. DNA extraction was carried out from young leaves using a kit for isolation of NC Sample NC manufactured by Agrodiagnostika LLC according to the manufacturer's protocol. Fermentas production kits were used for PCR. Identification of the cladosporosis resistance gene was Cf-19 performed using the DNA marker R7. The presence of a fusarious wilting resistance gene was determined by a I-2/5 marker. The amplification results were visualized by agarose gel electrophoresis.Results. During the research, a collection of varieties and hybrid forms of tomato of the Michurinsky GAU was analyzed in order to identify genes for resistance to cladosporiosis Cf-19 and fusarium wilt I-2. A total of 52 genotypes were analyzed. It was found that most samples (41 samples) are characterized by a heterozygous state of the Cf-19 gene. All indeterminant and semi-determinant forms had both alleles. Of the 23 determinant forms presented in the collection, 10 had only one allele corresponding to recessive homozygote. Among all analyzed tomato genotypes, no dominant homozygous forms were noted. The study of the collection revealed several alleles of the I-2 gene. In total, four fragments corresponding to various alleles were amplified. A total of 50 resistant genotypes have been identified in the collection. Two alleys of the I-2 gene (633/693 bp) were identified in 42 tomato samples. Four varieties are homozygous in one allele (633 bp), which determines resistance. Three varieties have a second resistance allele (566 bp). One genotype has only an allele defining susceptibility (693 bp). On the basis of molecular analysis, as well as an assessment of the type of bush and fetal color, initial forms were selected with subsequent hybridization. 67 hybrid tomato plants were obtained. Evaluation of the presence of resistance genes showed that most of the resulting hybrids are resistant to cladosporiosis and fuzariosis. This is due to the presence of dominant alleles of Cf-19 and I-2 genes in a heterozygous state. Among the resulting hybrids, plants with a bark type of bush were identified. A total of 13 such plants were obtained.Conclusion. Thus, the work carried out allowed to obtain hybrid forms of tomato combine the signs of resistance to two pathogens of fungal diseases and the stem type of the bush. These forms are planned to be used in further selection work.

Nowadays, thanks to organic farming development, particular attention is paid to the biological methods of plants protection, especially from diseases. Therefore, new biological preparations creation and studying their effectiveness are promising directions. The aim of the research was to study the antagonistic activity of the bacteria Paenibacillus polymyxa and Bacillus amyloliquefaciens against some phytopathogens (Pseudomonas syringae van Hall, Fusarium oxysporum Schltdl, Alternaria alternata (Fr.) Keissl.), as well as their reaction to laser irradiation. The research was carried out in the Research Problem Laboratory “Biphotonika” of the Michurinsk State Agrarian University and the Department of Agricultural Microbiology of the Research Institute of Agriculture of Crimea in 2016–2021. The antagonistic activity of the bacteria was evaluated by the double culture method. The effectiveness of irradiation (as a result of their treatment with coherent light) was determined by the change in the number of bacterial cells in the suspension. The study of the activity of bacteria-antagonists against pathogens showed that the suppression of P. syringae, F. oxysporum, A. alternata growth in the double culture with P. polymyxa compared to the control variants was 32.5 %; 4.0 % and 77.9 %, respectively. B. amyloliquefaciens suppressed the growth of P. syringae by 25.9 %, F. oxysporum – by 49.0 %; A. alternate – by 61.1 %. An increase in the number of cells in suspensions of P. polymyxa and B. amyloliquefaciens after coherent light irradiation by 26.6 % and 36.7 %, respectively, was also found. Thus, to control P. syringae, bacterial strain of P. polymyxa P was more effective. The bacterial strain B. amyloliquefaciens 01-1 showed antagonistic activity against F. oxysporum. Both studied microorganisms were effective against A. alternata. To increase the activity of cell division of antagonist strains of phytopathogens, it is advisable to use coherent light irradiation. In future, it is advisable to test the level of antagonistic activity of the bacteria P. polymyxa and B. amyloliquefaciens after laser irradiation.

This article discusses the problems of working with the endemic species O. hosiei. Analysis of the composition of the epiphytic microbiota of the seeds showed a high level of their contamination with fungi and bacteria. It is shown that the removal of the seed coat and the use of laser irradiation in the complex make it possible to increase the number of viable seeds and healthy seedlings. It is recommended to use complex methods of reducing the level of infectious background and stimulating the immune system of plants.

The problem of increasing activity of phytopathogen antagonist bacteria under the influence of laser irradiation is considered in this paper. Studies on Bacillus subtilis and Pseudomonas fluorescens from various plant protection products have shown that use of laser irradiation leads to an increase in the number of cells in bacterial suspensions. This indicator increased to a maximum of two times at effective exposures in comparison with the non-irradiated variants. That was justification for the need to study the nature of the impact of excessive content of metabolites in the substrate synthesized by such a quantity of bacteria from biological products, which is 2 or more times higher than the number of cells in the standard solutions. With a twofold and fourfold increase in the concentration of metabolites of the studied bacteria compared to their standard content in the medium, the photosynthetic activity of cucumber microplants increased by more than 32%. This suggests that laser stimulation of bacteria – agents of biocontrol of diseases does not adversely affect the functional state of plants.

La pérdida de vigor en semillas de tomate (Solanum lycopersicum L.) por acción de envejecimiento es una condición normal. Este estudio proporciona una referencia futura en cuanto a las posibles aplicaciones de tratamiento con radiación láser roja en semillas de tomate antes de la siembra para mejorar el vigor de semillas envejecidas. El objetivo de este estudio fue analizar los efectos de la irradiación láser en semillas de tomate envejecidas, sobre la tasa de germinación y crecimiento. Se hipotetiza que al menos un tratamiento de irradiación láser roja podría mejorar el vigor de las semillas. Dos grupos de semillas fueron utilizadas, uno con 11 años de envejecimiento y otro con semillas envejecidas 11 años más 24 h de envejecimiento artificial. Para la radiación se utilizó un diodo láser rojo 660 nm con una potencia de 100 mW, a una densidad de radiación de 0.2 mW cm-2, ocho tiempos de exposición a la radiación láser y un testigo como control. Los datos fueron sometidos a un análisis de varianza y las medias fueron comparadas por la prueba  de Tukey (HSD; p ≤ 0.05). En semillas con 11 años de envejecimiento, el tratamiento láser a 120 s mejoró el vigor de las semillas en 125  %, a consecuencia de un aumento en el crecimiento de la radícula (167  %, p ≤ 0.05) respecto al control (100  %). Por otro lado, el tratamiento láser a 60 s mejoró la tolerancia al estrés por envejecimiento artificial, el índice de vigor aumentó 143 % respecto al control (100 %), como consecuencia de una mejora en germinación del 162 % y en el crecimiento del hipocótilo (130 %, p ≤ 0.05), respecto al control (100 %). La radiación láser roja sobre semillas de tomate afectadas por envejecimiento natural o artificial puede influir en los procesos de foto morfogénesis e incrementar el vigor de las semillas.