Том 57, № 2 (2023)

The class Archaeorhizomycetes (Taphrinomycotina, Ascomycota) is a cosmopolitan group of fungi associated with the plant root system. Representatives of this class are extremely poorly studied due to the difficulty of cultivation, but sequences belonging to Archaeorhizomycetes are often detected during sequencing of natural substrates. Four unique sequences belonging to Archaeorhizomycetes were obtained during a study of the diversity of fungi associated with the orchid Goodyera repens by next-generation high-throughput sequencing of the ITS2 site. One sequence identical to Archaeorhizomyces borealis was identified in Russia for the first time, while two sequences presumably belong to a yet undescribed genus. One sequence belonging to an undescribed species of the genus Archaeorhizomyces is the most frequently detected in all types of samples (sod-podzolic soil, coniferous tree roots, rhizosphere, and orchid roots). The presence of nucleotide sequences of representatives of this class in the root system of Goodyera repens was shown for the first time, and the presence of one sequence in free soil was shown for the first time. The sequences were deposited in the GenBank database.

Thrombolytic properties of the micromycete Tolypocladium inflatum 62a isolated from the White Sea soils exoproteinases preparation, as well as its individual fractions, obtained after isoelectric focusing, were studied in comparison to the closest analogue, the producer of thrombolytic enzymes T. inflatum k1. A pronounced thrombolytic potential, the presence of fibrinolytic and plasminogen activator activity, specific proteolytic activity with respect to certain substrates (plasmin-like and subtilisin-like) as well as a prolonged thrombolytic effect in connection to fibrin clots were demonstrated, which can be used in the development of new drugs for the thrombotic conditions treatment, the development of anti-hematoma drugs for external use as well as diagnostic kits for the pathology of the human hemostasis system.

The effect of pre-sowing seed treatment with light in the red spectral region on the resistance of melon plants (Cucumis melo) of the cultivar Kichkintoy to Fusarium wilt damage caused by Fusarium oxysporum f. sp. melonis was investigated. The directly-opposite effects of red and far red light on the degree of plant damage by the pathogen, which was determined by the special symptoms of the disease on the leaves and stems of plants, were revealed. When alternating seed treatment with red and far red light, the final effect was determined by the type of irradiation that acted last. The results of photobiological testing made it possible to establish the participation of the phytochrome system in the control of the resistance of melon plants of the cv. Kichkintoy to Fusarium wilt. It is shown that there is a high positive correlation between the parameters of chlorophyll fluorescence induction of leaves reflecting the functional activity of the photosynthetic apparatus and the degree of damage to plants grown from non-irradiated seeds and seeds irradiated with red light. The results of the conducted studies establish the possibility of effective regulation of the resistance of the melon cv. Kichkintoy to the defeat of  F. oxysporum f. sp. melonis through photoactivation of the phytochrome system of seeds before sowing.

For the first time in Western Siberia, production tests of an experimental prototype of the drug based on the entomopathogenic fungus Metarhizium robertsii were carried out. Its ability to significantly restrain the development of potato rhizoctoniosis throughout the entire growing season is shown. A significant decrease in the death of sprouts and the development of rhizoctoniosis on the stems was established in comparison with the control and chemical protectant. In the area with the use of M. robertsii, a significant increase in the number of healthy tubers (by 2.5 times) was noted, the number of tubers with sclerotia decreased by 2.8 times compared to the control. The effectiveness of M. robertsii in the suppression of rhizoctoniosis was high at all stages of potato ontogeny and amounted to 52–84%. In laboratory experiments in the presence of M. robertsii, a significant inhibition of the formation of Rhizoctonia solani sclerotia on tubers was established, as well as a decrease in their viability and size.

The present report continues the series devoted to rare and interesting species of microfungi from various regions of Russia that cause rust, shoot deformations or leaf spots, and highlights Pseudocercosporella filipendulae (Mycosphaerellales, Ascomycota), a rare species new to Saint Petersburg City (Russia). The morphology of the species was repeatedly studied, emphasizing the conidia variability. This note gives further information on the distribution of the species in Russia, as well as the size of its conidia.