Scarce research into the secondary metabolites of the fungi Pseudogymnoascus spp. has shown a hidden biosynthetic potential for biologically active compounds. This work investigated the biosynthesis of secondary metabolites by two Pseudogymnoascus fungal strains, VKM F-4518 and VKM F-4519, isolated from the surface soil layer of the Kolyma Lowland, Russia, in the Arctic. In these strains, 16-membered trilactone macrolides, (+)-macrosphelides A and B, were identified using 1D and 2D NMR, UHRMS, and optical rotation data. In the fungi of this genus, these metabolites were found for the first time. The studied strains are highly active producers of macrosphelide A, which is being considered as a promising agent for the cure of cancer. Using the antiSMASH secondary metabolite analysis tool, we found that the genome of strain VKM F-4518 contained 32 of the biosynthetic clusters of the secondary metabolite genes (BGC) and that of VKM F-4519 had 17 BGCs. Based on the comparison of the cluster of macrotriolide genes from the fungus Paraphaeosphaeria sporulosa, we found the complete supposed cluster BGCs of macrosphelides in the genomes of two Pseudogymnoascus strains using the BLAST+ program.

Most Fusarium species are known as endophytes and/or phytopathogens of higher plants and have a worldwide distribution. Recently, information discovered with molecular tools has been also published about the presence of these fungi in the microbiome of truffle fruiting bodies. In the present work, we isolated and identified three Fusarium strains from truffle fruiting bodies. All isolates were assigned to the same species, F. commune, and the strains were deposited in the All-Russian Collection of Microorganisms under accession numbers VKM F-5020, VKM F-5021, and VKM F-5022. To check the possible effects of the isolated strains on the plants, the isolates were used to infect sterile seedlings of Sarepta mustard (Brassica juncea L.). This model infection led to a moderate suppression of the photosynthetic apparatus activity and plant growth. Here, we present characteristics of the F. commune isolates: description of the conidial morphology, pigmentation, and composition of the mycelium fatty acids. Overall, this is the first description of the Fusarium cultures isolated from truffle fruiting bodies. Possible symbiosis of the F. commune strains with truffles and their involvement in the cooperative fatty acid production are proposed.

The importance of Pestalotiopsis and Neopestalotiopsis species as pathogens of economically important plants is steadily increasing, while knowledge of their phytotoxic metabolites remains limited. Eighteen new strains of pestalotioid fungi were isolated from various plant samples that showed visible symptoms of disease. These strains were evaluated morphologically, and phylogenetic analyses of the ITS (internal transcribed spacer) and tub2 (beta-tubulin) gene regions were performed for genotyping. The isolated strains from Castanea sativa wood and nut were assigned to the species Neopestalotiopsis clavispora (six strain) and P. chamaeropis (one strain); four strains of Neopestalotiopsis, and one strain of Pestalotiopsis were not identified at the species level. Five strains isolated from coniferous trees, such as cypress and fir, were assigned to the species P. monochaeta, P. verruculosa, P. hollandica, and N. chrysea. A strain isolated from the Vaccinium uliginosum L. shoot was diagnosed as N. megabetaspora. The pathogenicity of strains was confirmed in vitro on coniferous shoots, Granny Smith apples, and leaves of C. sativa. The most pronounced phytopathogenic properties were demonstrated by strains isolated from C. sativa and a blueberry shoot compared to strains from coniferous trees. The dihydropyrans pestalotin and 7-hydroxypestalotin were identified in these strains, except for P. chamaeropis. The strains, isolated from cypress and fir, mainly produced a range of other metabolites. The extracts of the strains exerted a phytotoxic effect on lettuce root growth, suggesting that the metabolites may be involved in the virulence of the phytopathogenic fungi Pestalotiopsis s.l. Using the extract of Pes21 N. megabetaspora—the most active producer of pestalotins—we demonstrated that the necrosis area on the leaves of V. uliginosum L. and Rubus idaeus L. increased consistently with increasing metabolite concentrations. Purified pestalotin and 7-hydroxypestalotin inhibited lettuce root growth at a concentration of 500 μg/mL and stimulated it at a concentration of 100 μg/mL. This work provides important insights into the regulatory role of metabolites in fungus–plant interactions and serves as a basis for developing new strategies for the maintenance of plant resources.

Aspergillus fungi are a source of low-molecular compounds of various structures possessing biological activities. We investigated the secondary metabolite profile of the soil fungus A. calidoustus VKM F-4916. The strain was found to synthesize new metabolites attributed to furoisocoumarins, which we named asperisocoumarin J and K, and a known siderophore desferritriacetylfusigen. The structure of asperisocoumarin J and K were determined by mass spectrometry and NMR spectroscopy. Asperisocoumarins J, K and desferritriacetylfusigen possessed a phytotoxicity, inhibiting the lettuce root growth. Sow thistle leaf and wheat leaf cuttings were sensitive to the action of asperisocoumarin J and K at a concentration of 5 mg/mL. Analysis of the structures of furoisocoumarins (asperisocoumarins J and K) using the online resource Pesti-DGI-Net showed that compounds had the physico-chemical properties favorable for pesticide development, in particular, fungicides and herbicides. An in-depth study of the phytotoxic properties of furoisocoumarins and their natural analogs is of interest in the context of the search for new herbicide compounds.