Том 58, № 3 (2024)

The information about species composition and conformation characteristics of microfungi’s complexes in the soil and leaf litter of specially protected natural areas of Vietnam. The mycological examinations of the Bu Zia Map National Park were carried out for the first time. List of species that was found by dilution plate method from 60 samples includes 88 species of microscopic fungi belonging to 42 genera and 15 types of sterile forms. 13 species of them were not observed previously for Vietnam. Mucoromycota was represented by only two species that related to the order Mucorales. Basisiomycota was represented by only one species. The most of identified fungi belongs to Ascomycota, domitant part of them is anamorphic. The leading orders are Eurotiales (42 species) and Hypocreales (17 species). Among the anamorphic forms there is a lot of different species Aspergillus and Penicillium. In soil from dipterocarp forest were identified 36 species microscopic fungi from 19 genera and eight sterile forms were isolated. There are three species were included in the group of dominants: Aspergillus tubingensis, Penicillium ochrochloron, Trichoderma harzianum. On a forest with Lagerstroemia sp. (Lythraceae) was found 47 species from 24 genera and 4 sterile forms were isolated. In the palm tropical forest area with Arenga westerhoutii (Arecaceae) 44 species of micromycetes from 27 genera and 5 sterile forms were isolated. The number of typical (dominant and frequent) species is very large, especially for the complex of micromycetes of the soil. Purpureocillium lilacinum and Trichoderma harzianum were also present. Rare tropical fungi have been found, such as Heterocephalum taiense, Chaetomella circinoseta and C. raphigera – soil fungi that are usually isolated from tropical soils and plants. Endocalyx melanoxanthus that has a tropical distribution and is associated with palm trees was found in Vietnam for the first time. The micromycete Thielaviopsis radicicola which is a rather serious pathogen of palm was found in the soil in a forest area with a predominance of Lagerstroemia sp. Complexes of micromycetes of the studied forest areas are divided into groups according to the types of habitats studied and by the types of different substrates. The complexes of micromycetes that were found in the soil and on the litter of the Lagerstroemia forest are very different. The degree of study of the species composition for all habitats is not very high: from 56 to 78%. Further studies of this group are promising and may lead to the identification of new species.

We investigated the seasonality of myxomycete fruiting body formation under natural conditions in the field during four years in the Polistovo-Lovatskaya bog system (Northwestern Russia). It was shown that the species diversity of myxomycetes peaks in mid-summer and gradually decreases afterwards. The species composition of myxomycetes varies depending on the season. There were five phenological groups distinguished: summer, early autumn, late autumn, spring and species without pronounced periods of mass formation of fruiting bodies. It is shown the list of identifiable taxa may significantly vary in different years and there are widespread species that do not form sporophores every year. Thus, when conducting field studies, it is necessary to make observations over several years and throughout the entire snowless period.

The genus Armillaria is an essential component of forest ecosystems playing very important ecological role in dead wood decomposition, but it often becomes a serious pathogen causing white root rot in trees. It is also known that Armillaria species significantly differ in the level of pathogenicity. Thus, accurate identification of Armillaria is critical for assessing the risk of tree disease. In this study we analyzed 28 Armillaria isolates from Siberia and the Far East using nucleotide sequences of ITS, IGS-1-1 and TEF-1α gene regions and generated phylogenetic trees based on maximum likelihood method. In total, four Armillaria species were identified: A borealis, A. cepistipes, A. ostoyae and A. gallica. A. borealis was the most frequent among collected isolates (18 out of 28 isolates). A. gallica, A. cepistipes and A. ostoyae were much less frequent with two, five and three isolates out of 28, respectively. Thedistribution of Armillaria species in Siberia and the Far East was described for the first time. It is concluded that further studies are necessary to determine the role of Armillaria in trees pathological dieback, and A. borealis should be a key focus.

Pyrenophora tritici-repentis causing the tan spot of wheat produces specific necrotrophic effectors Ptr ToxA, Ptr ToxB and Ptr ToxC, inducing necrosis and chlorosis on the leaves of susceptible varieties. Based on the ability of P. tritici-repentis strains to produce specific necrotrophic effectors or their combinations, the eight races of the pathogen are distinguished. Monitoring the race composition of P. tritici-repentis populations is necessary to assess the evolutionary potential of the pathogen and develop a methodology for breeding wheat cultivars with long-term resistance. We analyzed 179 monoconidial P. tritici-repentis strains from Kazakhstan and Russia populations in 2020–2022. The widespread distribution of races 2 and 4 was revealed, strains of which were present in each analyzed P. tritici-repentis population with a frequency of 2–36% and 7–82%, respectively. The dominance of avirulent race 4 was noted: the strains of this race accounted for 27% of all analyzed P. tritici-repentis strains. Molecular identification of the ToxA and ToxB genes, as well as toxb, a homolog of the ToxB gene, in 118 P. tritici-repentis strains from six populations revealed the presence of the ToxA gene in 69% of the analyzed strains. The ToxB gene was not detected in any strains, while the toxb gene was found sporadically and was identified in the genome of 18 P. tritici-repentis strains (9%), most of which were avirulent and belonged to race 4. In PCR with specific primers for ToxA gene of ten P. tritici-repentis strains a product of ≈ 800 bp was amplified, which turned out to be significantly larger than expected. This was explained by the presence of an insertion in the amplified region of the ToxA gene. All P. tritici-repentis strains with the ToxAL were assigned to races 4 and 5, which do not form the necrotrophic effector Ptr ToxA. The structure of the ToxAL gene and its protein product is the subject of further research.