Mycology and Phytopathology

As a result of the long-term research, 63 fungal species belonging to 52 genera, 37 families, 16 orders, 5 classes, and 2 divisions (Ascomycota and Basidiomycota) of the kingdom Fungi were recorded on three hazel (Corylus) species in the Rostov region. Agaricomycetes (24), Sordariomycetes (17), and Dothideomycetes (12) were the three classes with the highest number of species. Lachnella alboviolascens and Trimmatostroma betulinum can be considered as first recorded on hazels in Russia and in the world; Chaetosphaeria ovoidea, Melanomma campylosporum and Sillia ferruginea are first found in the Rostov region. The greatest numbers of fungal species were observed on branches (23) and trunks (21), while the smaller numbers were recorded on twigs (12), leaves (10), and nut kernels (9). The majority of the recorded fungi (41, 60.1%) were plant parasites (pathogens of plants), including two obligate parasites (powdery mildews), 10 facultative saprotrophs (other phytopathogens), and 29 facultative parasites (opportunistic phytopathogens); only 22 species were saprotrophs (non-pathogenic). Of the 63 fungal species found on hazels in the Rostov region, 53 (84.1%) were also recorded on many other woody plants, while only 10 species were found exclusively on plants belonging to the Corylus genus or the Betulaceae family. The largest number of fungi was recorded in the semi-abandoned hazel plantations in Donskoye forestry (59) and in the hazel collections of the Botanical Garden of the Southern Federal University in Rostov-on-Don (36), much less in urban plantings (18) and private gardens (15). Only 15 species, mostly plant pathogens, were found in all types of habitats, and only five fungi were common or widespread species and are the main fungal pathogens of hazels: Phyllactinia guttata and Erysiphe corylacearum (powdery mildews), Pezicula cinnamomea (twig and branch dying), Chondrostereum purpureum, and Stereum hirsutum (trunk rot). The research of powdery mildews revealed that the invasive Erysiphe corylacearum, which has become common in the Rostov region since the first record in 2017, is more harmful than the native Phyllactinia guttata s.str. due to its early seasonal growth and damage to young shoots and leaves. However, due to the annual phenopause in powdery mildew growth caused by summer heat in July and August, the harm inflicted by Erysiphe corylacearum was minimal and not crucial for the viability and productivity of hazel. The comparison of the ascomycete species composition of the Rostov region and the seven regions/countries by the Kulczynski binary index (modified by S. P. Zhukov) revealed the highest similarity between the Rostov region and the Crimean peninsula because of the similar semi-arid regional climates and geographical proximity, the lower similarity with the neighboring Krasnodar region and with the former regions of Eastern Ukraine, much lower similarity with more distant regions of Russia (Moscow and Northwest Russia), and minimal similarity with other countries (Georgia and Poland).

Entyloma guaraniticum was discovered on Bidens pilosa in the Ta Dung Nature Reserve in Vietnam in 2022. This record is new to Vietnam. The record is supported by morphological and molecular data. A description of the species and information on its distribution are provided.

There are 42 species of fungi (Ascomycota, Basidiomycota) collected for the first time in Taimyr district of Krasnoyarsk Krai, and 13 species are the second – fourth finds. 25 species were collected on driftwood along the shores of lakes and rivers, and 11 species on firewood at the mountain base. 23 species develop in anthropogenic habitats on alien substrate, building structures, firewood and lumber. Four species were identified in anthropogenic conditions, which are first reported in the Russian Arctic (Cytospora chrysosperma, Didymella pomorum, Pleurotus abieticola, Sporocadus lichenicola).

The functional features of the implementation of cotton protective reactions to the most dangerous pathogens, Verticillium dahliae and Fusarium oxysporum, Xanthomonas malvacearum and Rhizoctonia solani – were studied. The hypersensitivity reaction of cotton tissues infected with pathogens was controlled by methods of observing the movement and size of the zone of fluorescent substances and determining the amount of toxic compounds for pathogens – phytoalexins. Infection of cotton with Verticillium dahliae and Fusarium oxysporum already in the first days of incubation led to a bright blue fluorescence that spread upwards towards the growth point of the experimental plants. In cotton infected with Xanthomonas malvacearum and Rhizoctonia solani the color of the fluorescent zones was less intense. The rate of spread through plant tissues, especially at the initial stages of the latent period, was significantly lower. In addition, the content of post-infection inhibitors in the tissues of xylem vessels of cotton infected with gummosis and root rot was recorded at a significantly lower level compared to the experimental plants infected with Fusarium and Verticillium wilt. On the 20th day of incubation, a significant increase in the total content of phytoalexins was noted in experimental cotton plants infected with root rot and gummosis, but the amount of the main phytoalexin – isohemigossypol in the tissues of these plants reached only 50% of the level of samples infected with Fusarium and Verticillium wilt. A comparative analysis of the effect of the studied pathogens on the intensity of the hypersensitivity reaction and the parameters of chlorophyll fluorescence induction indicate the possibility of using these methods at the initial stages of the incubation period in infected plant tissues for early detection of cotton disease resistance. The establishment of a positive correlation between the results of fluorescent analysis and the indicators of the effectiveness of the hypersensitivity reaction indicate the advisability of an integrated approach to assessing the resistance of cotton to pathogens.

Fusarium culmorum is a hemibiotrophic phytopathogenic fungus that causes Fusarium head blight, Fusarium root rot and Fusarium crown rot of barley and wheat. These diseases result in reductions in yield as well as in grain contamination with mycotoxins which are dangerous to human and animal health. In this work, the early stages of the interactions between F. culmorum and barley with different resistance to root rot were studied. Barley responses were assessed by the intensity of expression of the genes PR1, PR4, LOX, PAL, NPR1, WRKY33, WRKY34 associated with pathogenesis. The state of F. culmorum in barley roots was determined by the amount of its DNA and the intensity of expression of the TRI13 gene encoding the production of trichothecene toxins by the fungus. As a result, differences in the responses of barley of two genotypes to F. culmorum colonization were established. In medium-resistant barley, in response to the pathogen attack, the PR1, PR4, and LOX genes were induced earlier than in susceptible barley. In medium-resistant barley, the expression of protective genes was increased more often than in susceptible barley compared to the control. An increase in the amount of F. culmorum DNA and the level of toxins produced by it was accompanied by suppression of the expression of the PR4, PAL, WRKY33, and WRKY34 genes in susceptible barley. In medium-resistant barley during this period, there was no suppression of protective genes; on the contrary, compared with the control, the expression of the PR1, PR4, LOX, PAL, and NPR1 genes was increased. The involvement of the studied genes in the interactions between barley of two genotypes and F. culmorum has been determined. The results obtained expand the knowledge about the molecular interactions between the parasite and the host plant in the barley – Fusarium culmorum pathosystem.

This article offers an in-depth exploration of the rare and little-known fungal species recently added to the collections of the “Herbarium of epixylic fungi, algae and lichens of the Saint Petersburg State Forest Technical University named after S. M. Kirov” (SPFUE). The acquisitions, made in 2025, contribute significantly to the herbarium’s growing repository of materials. Duplicate specimens were also transferred to the mycological herbarium of the Komarov Botanical Institute (LE F). The herbarium itself was founded in October 2024 with the objective of organizing materials that have been accumulated since the mid-20th century. Central to this foundation are the works and collections of prominent phytopathologists such as A. T. Vakin (1903–1966), I. I. Minkevich (1931–2017), and G. I. Zarudnaya. Covering a distinct thematic niche, the herbarium primarily focuses on fungi and lichens associated with the bark of living trees as well as unfallen and freshly fallen terminal branches. While the herbarium also includes powdery mildew fungi and leaf-spot-causing species on one hand, and tinder fungi on the other, these are less prominently represented. Beyond fungi, the collection houses epiphytic lichens and aerophytic algae, adding further depth to its biological diversity. Highlighting exceptional acquisitions from 2025, the article delves into detailed ecological, morphological, and distributional notes on three noteworthy species: Melanconis alni, Illosporiopsis christiansenii (Ascomycota), and Puccinia phragmitis (Basidiomycota). Additionally, insights into herbarium specimens stored at both LE F and SPFUE are provided, enhancing understanding of their scientific significance.