Volume 58, Nº 4 (2024)

Myxomycetes are amoeboid fungus-like organisms (Amoebozoa) with a unique life cycle characterized by a great morphological diversity of fruiting bodies. Due to the similarity of these structures to the fruiting bodies of some representatives of Ascomycota and Basidiomycota, myxomycetes have been classified as fungi since the first known scientific description in 1654. Only in the XIX century, when their life cycle was studied, the difference of this group from fungi became clear. During the same period, microscopic structures of fruiting bodies, as well as ornamentation of the spore surface, began to be considered as diagnostic features. Due to this, in the period from the end of XIX to the middle of XX century, a rather stable system was formed. However, as further studies have shown, both macro- and micromorphological characters are often quite variable, depend on environmental conditions, and often result from a convergent evolution, which causes difficulties in defining species and taxonomic units of higher ranks. Since the first decade of the 21st century, thanks to the development of molecular genetic methods and accumulation of data on nucleotide sequences of marker genes together with the improvement of microscopic studies, it has been possible to obtain data on the evolutionary relationships of different groups of myxomycetes. A milestone in this process was the publication of the first phylogenetic system of myxomycetes in 2019. This work was the starting point for a number of studies on the relationships of different groups of myxomycetes at a lower taxonomic level. Thus, there has been a surge in the number of studies that bring us closer to constructing a natural system. The latest iteration of the myxomycete system, incorporating all modifications and enhancements as of June 2024, is presented.

This paper is a first report on the results of macrofungi studies in the planned protected area (PPA) Maksimjarvi, situated in the middle part of the Republic of Karelia, near the Finnish border. The forests there are predominantly north-boreal pine stands with a smaller proportion of spruce stands. The data were gathered during the fieldwork carried out in 2022 by O. Predtechenskaya and A. Ruokolainen and combined with data from Finnish colleagues carried out in 2012 and 2016. The records are supported by specimens deposited in the herbarium of the Karelian Research Centre RAS (PTZ) and Botanical Museum of the University of Helsinki (H). The current checklist for the Maksimjarvi territory includes 196 species of 121 genera, 57 families, 14 orders of aphyllophoroid, agaricoid and gasteroid fungi. The records include the first finding of Phellodon secretus in the Republic of Karelia, and 3 fungal species (Botryobasidium laeve, Peniophora septentrionalis, Phellodon secretus) were found for the first time in the biogeographic province Karelia pomorica occidentalis. Surveys of the Maksimjarvi PPA revealed 17 fungal species listed in the Red Data Book of the Republic of Karelia (2020). The area is known to harbor indicator and specialized fungal species of biologically valuable forests. The need to designate it as a conservation area is substantiated with regard to the ongoing formation of the PA system of the Green Belt of Fennoscandia and the Republic of Karelia.

We have summarized the results of xylotrophic agaricoid basidiomycetes long-term monitoring in some types of indigenous and derived forests in the southern taiga subzone of Perm Krai. We carried out the research by a stationary method on the test 50×20 m areas, one in each type of forest: spruce forest at the brook, sorrel spruce forest and birch forest. We did the work in three periods: I – 1975–1977, II – 1994–1996, III – 2010–2012. The collection of material was carried out annually: in August 3 times with an interval of 10 days (the species composition, number and air-dry biomass of basidiomes were taken into account), and in September once (only the species composition of fungi was taken into account). To date, we have established that the number of xylotrophic agaricoid fungi in the studied forest types varies from 60 (sorrel spruce forest) to 66 (birch forest). Most of the identified species belong to the Tricholomataceae family (37.7–43.3% of the total number of xylotrophic fungi species in each of the biogeocoenoses). There was an annual accumulation of detectable fungal species, with the largest number of species (67–75%) detected from 2 to 9 times, and 2–3% of them were permanent, occurring annually. There was relative stability of the species composition of higher vascular plants (Jaccard generality coefficient: J = 56–88) over time and more significant changes in the species composition of xylotrophic fungi (J = 36–50). The spruce forests had the most similarity of fungi species composition between the cenoses by periods (J = 44–52), and for the entire observation period, the sorrel spruce forest and birch forest had the maximum Jaccard index between cenoses (J = 56). The yield of xylotrophic agaricoid fungi in the studied cenoses varies by years of observation. The birch forest had the largest number and biomass of basidiomata for all the three periods of the research. A decrease in the number of basidiomes of xylotrophic fungi in the sorrel spruce forest was established with an increase in the average monthly air temperature in August (Spearman correlation coefficient: r_s = −0.70). The sorrel spruce forest was the most favorable for the biota of xylotrophic agaricoid basidiomycetes, both in number (Shannon index: H = 1.23) and in biomass (H = 1.20), during all the research, since the biota of xylotrophes of the specified cenosis was more diverse and its components were most aligned.

The work contains a comparative analysis of methods for storing pure cultures of macrofungi. The study used 20 species of macrofungi from various taxonomic and ecological-trophic groups. Storage was carried out using five methods: serial subculturing, storage under a layer of distilled water and three cryopreservation protocols: a protocol using blocks of agar medium, a “perlite protocol” and a “grain protocol”. For the selected cryostorage methods, various cryoprotective compounds (glycerol, trehalose) were used. Radial growth rate was used as a criterion for the state of crops. The values of the radial growth rate obtained immediately after isolation of the pure culture were chosen as the control. It has been shown that the most favorable for preserving the physiological activity of cultures are the storage method under a layer of distilled water, “perlite” and “grain” cryopreservation protocols.

Yellow rust (Puccinia striiformis f. sp. tritici, Pst) is a potentially dangerous disease of wheat. Genetic protection of wheat is an environmentally safe method of control. For its successful application, information on the structure of regional populations of the pathogen is needed. The purpose of these studies is to characterize the virulence and molecular polymorphism of Russian Pst populations in 2022. Wheat leaves with Pst urediniopustules were obtained from the North Caucasus (Krasnodar Territory, Dagestan, Kalmykia) and Northwestern (Leningrad region) regions. Virulence analysis was performed on 14 isogenic lines (AvocetNIL) and 15 differentiator varieties. The polymorphism of 20 microsatellite loci was evaluated in molecular analysis. We used SSR markers recommended by the Global Rust Reference Center. Virulence was studied in 74 monopustular isolates: 29 Dagestan, 10 Krasnodar, 5 Kalmyk, 30 northwestern. Resistance to all isolates was shown for lines with genes Yr5, Yr10, Yr15, Yr24, Yr26 and varieties Moro (Yr10, YrMor) and Nord Desprez (Yr3, YrND, Yr+). Isolates virulent to the AvYr17 line were detected for the first time in Dagestan and Krasnodar populations. They were moderately represented in the northwestern population (13%). Significant variation was observed in lines and varieties with the Yr1 and Yr3 genes. There was a decrease in virulence to Yr7 and YrSp compared to 2019–2021. 28 phenotypes (races) were determined in the virulence analysis (15 in Dagestan, 11 in North West, 3 in Krasnodar and 2 in Kalmyk). A common phenotype was noted for three North Caucasian Pst samples. The genetic distances between the identified phenotypes were estimated. In the multidimensional diagram, most of them combined together in a common group, with the exception of three Dagestan phenotypes with the fewest virulence alleles. According to the Fst index, Dagestan and Kalmyk Pst collections were characterized by high similarity; others differed moderately from them. The long-term virulence dynamics (2019–2022) of Pst populations in the Northwestern and North Caucasian regions was assessed. High similarity was determined between all regional population samples in 2019 and 2020. The northwestern and Dagestan populations differed slightly from them in 2021 and 2022. In 2022, the Krasnodar and Kalmyk populations were divided into separate groups, which differed from each other and from the main group. Long-term results of virulence analysis indicate a high dynamic of the structure of Pst populations in Russia. All North Caucasian isolates and 23 Northwestern isolates were used in the SSR analysis. Six loci (RYN3, RYN9, RYN12, WU6, RJO21, RJO24) were monomorphic. Three polymorphic alleles were identified in the RYN13 and RJO27 loci and two in the remaining studied ones. Significant deviations from the Hardy-Weinberg equilibrium are noted for most loci. The observed heterozygosity exceeded the expected one, which indicates an excess of heterozygotes and the clonal origin of the population. The studied collection of isolates was represented by 20 multilocus genotypes (MGs) (Dagestan and Northwestern – 11 each, Krasnodar – 3, Kalmyk – 1). Common genotypes were detected in Dagestan, Krasnodar and Northwestern populations (MG_1); Dagestan, Kalmyk and Northwestern (MG_2); Dagestan and Krasnodar (MG_3, MG_4). The genetic distances between MGs were estimated. In the multidimensional diagram, they are divided into 4 groups. The main group included 80% of MGs. One Dagestan MG, two Northwestern MG and MG_3 common for Dagestan and Krasnodar collections, significantly differentiated from the main group and among themselves. According to the Fst index, most regional Pst collections were moderately differentiated among themselves, with the exception of Dagestan and Kalmyk, which is consistent with the virulence analysis. According to the Mantel test, a moderate correlation was found between the results of virulence analysis and SSR (r = 0.6). This indicates that both analyses can be used in assessing the genetic polymorphism of Pst. The high variability of Russian populations based on virulence and microsatellite loci determines the need for annual monitoring of regional Pst populations in Russia.