Aim. To investigate the ability of our phytopathogenic fungal strain 502, earlier preliminarily identified as the phytopathogen Plectosphaerella melonis (syn. Acremonium cucurbitacearum), to have phytotoxic and/or plant growth regulatory activity. Methods. The phytotoxicity of strain 502, was studied by bioassays using the test cultures of corn (Zea mays L.), garden cress (Lepidium sativum L.), cucumber (Cucumis sativus L.), and onion (Allium cepa L.). The cytotoxicity and genotoxicity of the fungus were estimated using the Allium cepa-test. The mitotic index of the, the duration of mitosis phases, and the frequency of aberrant ana-telophases of Allium cepa L. roots meristem was also investigated. For this purpose, strain 502, was grown in the following culture media: synthetic Raulin-Thom medium for 10 days at 26 ± 2 °С. Cell-free filtrate (culture fluid) was used for the study. Ethylene production was quantified in culture filtrate using gas-chromatography meth- od. Ethylene measurement was performed every 7 days during 8 weeks. The determination was carried out using a gas chromatograph «Agilent Technologies 6850» (USA) fitted with a flame ionization detector, using commercial ethylene as a standard for identification and quantification Every experiment had three repeats. The reliability of experimental data was assessed by statistical methods using Statistica 12 (Stat-Soft Inc., USA). Results. Undiluted culture fluid (obtained by growing the fungus on liquid wort) of our strain 502 inhibited the growth of Z. mays seedlings by 14 %, L. sativum seedlings by 18 % (1 : 100 dilution) and stimulated the growth of L. sativum roots by 54 and 41 % (1 : 10 and 1 : 100 dilutions, respectively). The culture fluid, obtained by growing the fungus on Raulin-Thom’s synthetic agar, demonstrated a slight inhibitory effect on the seedlings and roots of L. sativum, and at the dilution of 1 : 1000 stimulated growth by 30 %. Insignificant changes in the mitotic index of the meristem of A. cepa roots were revealed at the effect of the culture fluid of P. melonis, strain 502, diluted at the ratio of 1 : 100 and 1 : 1000. At the same time, the number of cells at the prophase stage decreased 1.7 times (1 : 100 dilution). There is a significant increase in the number of cells at the metaphase stage – 1.3 and 1.4 times (dilution 1 : 100 and 1 : 1000, respectively), the anaphase stage – 2.1 and 1.8 times (dilution 1 : 100 and 1 : 1000, respectively) and the telophase stage – 1.8 times (1 : 100 dilution), as compared with the positive control (culture medium). The frequencies of aberrant ana-telophases in the apical meristems of the initial roots were 5.0 and 2.2 % (at the culture fluid dilution of 1 : 100 and 1 : 1000, respectively). We researched the abil- ity of P. melonis 502 to synthesize ethylene and the highest level of it was registered after 5 weeks of cultivation (111.78 nmol/h g). Conclusions: It was demonstrated by us that the culture fluid of strain 502 showed no phytotoxic effect on roots and seedlings of the investigated cultures, demonstrating the exclusion of phytotoxins from the possible range of effectors. No cytotoxic or genotoxic activity of the culture fluid was observed either. However, the culture fluid altered the dynamics of the cell cycle, in particular, shortened the prophase and stimulated the metaphase, anaphase, and telophase. The culture fluid of the fungus stimulated the growth of L. sativum roots depending on the nutrient medium, where the fungus was grown and cultivated. In particular, when growing the fungus on the liquid wort, the growth was higher by 54 and 41 % (dilution 1 : 10 and 1 : 100, respectively), when growing on synthetic Raulin-Thom’s medium – by 30 %. This demonstrates the ability of strain 502 to possibly synthesize growth promoting substances. Also, we have shown the ability of this strain to synthetize ethylene in vitro (111.78 ± 13.27 nmol/h per g), which can act as virulence factor. We consider the obtained results to be the first stage of the study on the mechanism of the interaction between pathogenic strain 502 and plants.

Fungal diseases cause signifi cant damage to agriculture. Plectosphaerella melonis (syn. Acremonium cucurbitacearum and Nodulisporium melonis) is a pathogen of cultivated plant diseases in Spain, Italy, Japan, USA, Egypt, and Ukraine. This review discusses the main results of research related to this phytopathogen. By morphological and cultural features, P. melonis is a morphologically intermediate species between A. strictum and A. charticola, however, 5.8S-ITS regionbased phylogenetic analysis showed that P. melonis is a monophyletic taxon more closely related to Plectosphaerella than to other species of the genus Acremonium. The most susceptible plants are at the stage of germination; however, the development of the disease is manifested in the fruiting period. For a comprehensive assessment of virulence, real leaf area (RLA) of the first two leaves, lesion of hypocotyl (RH), root collar (RSR), primary (R1R) and secondary roots (R2R) are measured. P. melonis affects the root system, in particular the root collar and hypocotyl, and colonizes the epidermis and cortex of the root centrographically towards the stem. The range of host plants includes Cucurbitaceae, however, peppers, tomatoes, basil, and parsley are infected as well. Plants vary in susceptibility depending on the species and even variety. The pathogenic response of plants differs depending on the growing conditions (protected and open soil), the interaction between the pathogen and competing microorganisms, and other ecological and trophic relationships. The main means of control are the use of long-term crop rotations and the selection of resistant varieties. In Ukraine, a strain of the antagonist fungus Trichoderma viride was selected, which is an effective means for controlling P. melonis 502. The aim of our work was to establish the role of P. melonis in the development of diseases of cultivated plants.

Objective. To study the efficacy of the use of a new strain of Trichoderma viride IMB F-100076 with high antagonistic and cellulolytic activity, in particular its effect on the photosynthetic apparatus and the yield of corn plants. Methods. Study of the effect of T. viride IMB F-100076 on corn94 yield was performed under the conditions of a three-year small-plot field experiment on sodmedium-podzolic soil. The content of chlorophyll a and b in the plants of the experimental variants was determined by spectrophotometry. Methods of mathematical statistics were used in processing the obtained data. Results. Data from a three-year field experiment showed that the application of straw had a negative effect on the yield of corn, which averaged 7.72 t/ha that is 12.3 % less than in the variant without the application of straw (control). Application of the antagonist fungus T. viride IMB F-100076 to the soil simultaneously with straw allowed to obtain an average yield of 9.5 t/ha during three years of study, which is 23 % higher than in the variant with straw. In the control variant (without application of straw and fungal suspension), the yield averaged 8.8 t/ha, which is 14 % higher than in the variant with straw not treated with fungus. It was shown that the content of chlorophylls in corn leaves increases under the influence of T. viride IMB F-100076. For instance, the total content of chlorophyll a and b was 261.04 mg/100 g of leaves, which is 39.0 % higher than in the variant with straw not treatment with a suspension of the fungus, and 15.3 % higher than in the control variant. The obtained results highlight that the treatment of straw with the fungus T. viride IMB F-100076 had a positive effect on the formation of the photosynthetic apparatus of corn plants. Conclusion. Simultaneous application of wheat straw and T. viride IMB F-100076 micromycete, which is characterized by high antagonistic and cellulolytic activity, provides a significant increase in corn yield versus the variant with straw not treated with fungus. The content of chlorophylls a and b in the leaves increases.