The Proteaceae, a diverse family of woody flowering plants in the Southern Hemisphere, contains many species known to be susceptible to Phytophthora cinnamomi, both in the natural environment and in cut-flower orchards. Very little is known about the prevalence of P. cinnamomi and other oomycetes across these landscapes. To address this knowledge gap, we used a double ITS1 and RPS10 gene metabarcoding approach and traditional isolation protocols to investigate oomycetes in orchards and natural stands of Proteaceae across South Africa, South Africa (eastern and western), Australia, and Europe. The RPS10 primers amplified more samples, including various Pythium species, while the ITS primers detected more Phytophthora phylotypes. Both datasets showed that geographic regions influenced oomycete species richness and community composition, while they did not show any variation between orchards and natural vegetation. RPS10 metabarcoding detected the largest number of species and provided greater statistical confidence than ITS1 when considering oomycete species composition. Metabarcoding also showed that orchards had a higher abundance of P. cinnamomi compared to native stands, although this was not found when isolating through baiting of roots and rhizosphere soil. Direct isolation and metabarcoding are complementary, with metabarcoding serving as an early detection tool. However, it cannot distinguish living viable propagules from residual DNA of dead propagules, limiting its use for diagnostic purposes related to Phytophthora management and control. These results, along with those of other recent studies, show that metabarcoding offers an effective tool to describe the dynamics of soil oomycetes in different ecosystems.

Convergent evolution is the phenomenon of similar traits evolving independently in different lineages of the tree of life. Studying convergent evolution provides an excellent opportunity to understand natural selection for specific traits and physiological constraints to evolution that allow a broadened view on evolutionary mechanisms as a whole. Smut fungi, a polyphyletic group of plant-parasitic fungi with a specific infection and life cycle pattern, are a prime example of convergent evolution. Most notably, smut fungi in the genus Microbotryum that belongs to the subdivision Pucciniomycotina and smut fungi from the subdivision Ustilaginomycotina show strong similarities despite millions of years of independent evolution. However, the conceptual connections drawn between the two groups are scarce, thereby limiting the opportunities for exploring convergent evolution between these taxa. To facilitate knowledge exchange within the research community, we provide a summary of databases, molecular and biological tools and a brief introduction to the structure of populations and the characteristics of host specificity in both groups. Furthermore, we compare the life cycles and research emphases between the two groups. The comparisons are supplemented with an analysis of genome composition and gene function, which aims to advance research on the convergent evolution of smut fungi using existing data.

Riparian alder forests are threatened by Phytophthora across Europe. Comparative studies of the pathogenicity of Phytophthora species are crucial for developing effective management strategies. Although only a limited number of species, particularly P. × alni, lead to tree decline in natural environments, many species demonstrate pathogenicity in inoculation trials. Phytophthora species vary in their ability to infect different tissues, such as phloem and xylem, and trigger defence responses in the host through the formation of tyloses and callose. By comparing the histological responses of alder to various Phytophthora species, we can gain insights into the success of P. × alni and the potential damage that could be caused by other species. To investigate the defence strategies of black alder (Alnus glutinosa) against attack by Phytophthora and Halophytophthora species present in Catalonia (NE Spain), we conducted inoculation trials on saplings using nine potentially pathogenic species and compared the histological responses. Phytophthora × alni and P. plurivora were the most aggressive species followed by other exotic species such as P. × cambivora and P. cactorum. Phytophthora × alni and P. plurivora were equally damaging despite the higher prevalence of P. × alni in declining alders in natural settings. Although P. × alni mainly invaded the phloem, P. plurivora also invaded the xylem and triggered the production of tyloses. Histological analyses revealed a diverse range of plant responses to infection by Phytophthora species, providing a better understanding of their adaptability in natural environments compared with solely observing lesions. The low level of callose production in saplings inoculated with P. × alni compared with callose production in saplings inoculated with less pathogenic species suggests that P. × alni can evade recognition by the host and, hence, could partially explain its success.

Protoilludene-type sesquiterpene aryl esters are a unique and very diverse compound class that were exclusively isolated from members of the genus Armillaria (Agaricomycetes, Physalacriaceae) up to this point. Herein, we describe the isolation and structural characterization of 5′-O-methyl-14-hydroxyarmillane (1), a new armillane-type derivative, that was obtained from submerged cultures of Guyanagaster necrorhiza (CBS 138623) together with the known congeners melleolide G (2), melleolide B (3), and 10-dehydroxy-melleolide B (4). ROESY data and coupling constants assigned the relative configurations of 1, while common absolute configurations were confirmed from comparison of its ECD spectrum to the one of 10-hydroxy-5′-methoxy-6′-chloroarmillane (5). Additionally, the configuration of melleolide G (2) was revised based on observed ROESY correlations. It is the first time that protoilludene-type sesquiterpene aryl esters were isolated from another genus, namely, Guyanagaster, that is closely related to Armillaria. 1–4 were evaluated for their biological activities in a serial dilution assay against several yeast, fungi, and bacteria, as well as in a cytotoxicity assay against different cell lines. Compound 4 was moderately active against Bacillus subtilis, Staphylococcus aureus, and Mucor hiemalis. Furthermore, 1, 3, and 4 showed weak cytotoxic effects against the mouse fibroblast cell line L929 and the cervix carcinoma cell line KB3.1.

In fungi, little is known about connections between volatile organic compound (VOC) formation and developmental stages that are amongst others triggered by fruiting-related genes (FRGs). We analysed the volatilomes of Schizophyllum commune during different developmental stages in a variety of FRG-deletion strains and wild-type strains. The deletion strains Δtea1Δtea1, Δwc-2Δwc-2 and Δhom2Δhom2 were unable to develop fruiting bodies, and Δfst4Δfst4 formed only rudimentary fruiting body structures. Early developmental stages of these strains were dominated by esters, including methyl 2-methylbutanoate, ethyl 2-methylbutanoate, isobutyl 2-methylpropionate, and 2-methylbutyl acetate, of which the last three were not found in the headspace (HS) of the wild-type samples. Compared to the wild type, in the HS of hom2con samples, that are able to form fruiting bodies, methyl 2-methylbutanoate was the most abundant substance at early stages (68–81% of the total peak area). In contrast to fruiting body forming strains, Δtea1Δtea1, Δwc-2Δwc-2, Δhom2Δhom2 and Δfst4Δfst4 showed less sesquiterpenes in the HS. However, the sesquiterpenes found in the HS of FRG-deletion strains, namely, (E)-nerolidol, δ-cadinene, L-calamenene, α-bisabolol and β-bisabolene, were not present in hom2con or wild-type strains that mainly formed fruiting bodies and barely mycelium. Several sesquiterpenes, including α-guaiene, chamigrene and γ-gurjunene, were only found in presence of fruiting bodies. Our results show remarkable connections between FRGs, fruiting body development and VOC production in S. commune, especially counting for sesquiterpenes. Future studies are needed to reveal whether FRGs directly regulates VOC formation or indirectly by changing the phenotype.

Meliolales (black mildews) is an order of plant parasitic ascomycetous fungi in the tropics and subtropics. They are frequently overgrown and parasitized by other fungi, known as hyperparasites. During the last few years, species of hyperparasitic fungi on Meliolales have been collected in Benin and Panama. A new species of Paranectria and seven new reports of hyperparasites of different systematic groups are presented here with detailed descriptions and illustrations, together with new data concerning fungal hosts and host plants. The new species is called Paranectria longiappendiculata, characterized by exceptionally long appendages carried by the ascospores. New records for Benin and Panama are Calloriopsis herpotricha, Dimerosporiella cephalosporii, Isthmospora glabra, Isthmospora trichophila, Malacaria meliolicola, Paranectriella hemileiae, and Paranectriella minuta. Calloriopsis herpotricha is recorded for Africa and D. cephalosporii and P. hemileiae for America for the first time, suggesting an apparently pantropical distribution. Findings show a blatant lack of investigation on hyperparasitic fungi in the tropics. The phylogenetic positions of three of these newly reported species, C. herpotricha, D. cephalosporii, and P. minuta, are shown based on the analysis of internal transcribed spacer (ITS), large subunit (LSU), and small subunit (SSU) rDNA sequences. These sequences were generated in the context of the present study for the first time.

Fungal specimens parasitic on spider egg sacs (Araneidae sensu lato) were collected, isolated, and identified based on molecular phylogenetic analyses of five nuclear loci (ITS, LSU, TEF1, RPB1 and RPB2) combined with morphological data. In this study, one novel monotypic genus is described, Bhushaniella rubra for Thailand. Bhushaniella rubra is characterized by producing superficial perithecia. Its anamorph has a unique character by producing verticillate phialides with a slightly curved neck. A concurrent evaluation of the secondary metabolites of the mycelial extracts of the new fungus revealed the presence of picoline alkaloids of the penicolinate type, for which we propose the trivial names penicolinates F and G. Their chemical structures were elucidated by two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy and high resolution mass spectrometry (HR-MS). They only showed weak to no antibiotic activity and were devoid of significant cytotoxic effects.