Diversity and Communities of Fungal Endophytes from Four Pinus Species in Korea

Ant's Nest as a microenvironment: Distinct Mucoromycota (Fungi) community of the red wood ants' (Formica polyctena) mounds

Many social insect species build nests, which differ from the surrounding environment and are often occupied by specific organismal communities. These organisms may interact mutualistically or parasitically with the nest-builders, or simply co-occur, being able to survive in these microenvironments. In temperate forests, red wood ants (e.g. Formica polyctena) are known to create distinct, highly developed nests, which consist of large, above-ground mounds, built primarily out of plant matter collected from the forest litter. The microorganismal communities of such mounds remain understudied. As representatives of Mucoromycota fungi commonly engage in the decomposition process of the forest litter, they would be expected to occur in the mounds. However, it is still not known whether the Mucoromycota community of these ants' nests differ from the one of the surrounding forest litter. In order to distinguish mound-associated taxa, we characterized Mucoromycota communities of Formica polyctena mounds and the surrounding forest litter. We sampled four sites, twice in a season. Sampled material was plated on agar media and emerging Mucoromycota colonies were identified based on their morphology. Fungal identification was further confirmed using DNA barcoding. In order to compare described communities, PERMANOVA test and non-metric multidimensional scaling ordinations were used. To distinguish taxa associated with the mounds, multilevel pattern analysis was performed. Our results show that the Mucoromycota community of Formica polyctena's mound differs from the community of the surrounding forest litter. While representatives of Entomortierella lignicola and Absidia cylindrospora clade were found to be associated with the mound environment, representatives of Umbelopsis curvata and Podila verticillata-humilis clade were associated with forest litter, and were rarely present in the mounds. Our findings strongly suggest that the red wood ants' nest is a specific microenvironment in the temperate forest floor, which is a preferred microhabitat for the mound-associated Mucoromycota, possibly adapted to live in proximity to ants.

The Populations of Two Differently Medicine-Used Plants of Hedyotis diffusa and Hedyotis corymbosa Shoot-Assembling Rich Bacterial and Fungal Communities with Varied Compositions but Conserved Structures

The plant-colonized microbial communities have closely micro-ecological effects on host plant growth and health. There are many medicinal plants in the genus Hedyotis, but it is yet unclear about the shoot-assembled bacterial and fungal communities (SBFC) of Hedyotis plants. Hence, eight plant populations of Hedyotis diffusa (HD) and H. corymbosa (HC) were evaluated with 16S rRNA gene and ITS sequences, for comparing the types, abundance, or/and potential functions of SBFC at plant species- and population levels. In tested HD- and HC-SBFC, 682 fungal operational taxonomic units and 1,329 bacterial zero-radius operational taxonomic units were identified, with rich species compositions and varied alpha diversities. Notably, the SBFC compositions of HD and HC plant populations were exhibited with partly different types and abundances at phylum and genus levels but without significantly different beta diversities at plant species and population levels. Typically, the SBFC of HD and HC plant populations were presented with abundance-different biomarkers, such as Frankiaceae and Bryobacteraceae, and with similar micro-ecological functions of microbial metabolisms of lipids, terpenoids,and xenobiotics. Taken together, HD- and HC-SBFC possessed with varied rich compositions, conservative taxonomic structures, and similar metabolic functions, but with small-scale type and abundance differences at plant species- and population- levels.

Contribution to the characterization of the seed endophyte microbiome of Argania spinosa across geographical locations in Central Morocco using metagenomic approaches

Microbial endophytes are microorganisms that live inside plants, and some of them play important yet understudied roles in plant health, growth, and adaptation to environmental conditions. Their diversity within plants has traditionally been underestimated due to the limitations of culture-dependent techniques. Metagenomic profiling provides a culture-independent approach to characterize entire microbial communities. The argan tree (Argania spinosa) is ecologically and economically important in Morocco, yet its seed endophyte microbiome remains unexplored. This study aimed to compare the bacterial and fungal endophyte communities associated with argan seeds collected from six sites across Morocco using Illumina MiSeq sequencing of the 16S rRNA gene and ITS regions, respectively. Bacterial DNA was extracted from surface-sterilized seeds and amplified using universal primers, while fungal DNA was isolated directly from seeds. Bioinformatics analysis of sequencing data identified taxonomic profiles at the phylum to genus levels. The results indicated that bacterial communities were dominated by the genus Rhodoligotrophos, while fungal communities exhibited varying degrees of dominance between Ascomycota and Basidiomycota depending on site, with Penicillium being the most abundant overall. Distinct site-specific profiles were observed, with Pseudomonas, Bacillus, and Aspergillus present across multiple locations. Alpha diversity indices revealed variation in endophyte richness between seed sources. In conclusion, this first exploration of the argan seed endophyte microbiome demonstrated environmental influence on community structure. While facing limitations due to small sample sizes and lack of ecological metadata, it provides a foundation for future mechanistic investigations into how specific endophyte-host interactions shape argan adaptation across Morocco's diverse landscapes.

The genus Rachicladosporium: introducing new species from sooty mould communities and excluding cold adapted species

The fungal genus Rachicladosporium (Cladosporiales, Cladosporiaceae), typified by cladosporium-like Rachicladosporium luculiae, includes a morphologically diverse assemblage of species. The species of this genus were reported from different substrates, habitats and environments, including plant leaves and needles, twig, black mould on baobab trees, rocks and insects. In this study, four new Rachicladosporium species (R. europaeum, R. ignacyi, R. kajetanii, R. silesianum) isolated from sooty mould communities covering leaves and needles of trees and shrubs in Poland are described. The new species are delineated based on morphological characteristics and molecular phylogenetic analyses using concatenated ITS, LSU, and rpb2 sequences. All newly described species are nested in the main Rachicladosporium lineage (centred around the type species), which contains species that are able to grow at 25 °C. By contrast, four cold adapted, endolithic species known from Antarctica (R. antarcticum, R. aridum, R. mcmurdoi) and Italian Alps (R. monterosanum) form distant phylogenetic lineage and do not grow at this temperature. Therefore, they are accommodated in the new genus Cryoendolithus, typified by Cryoendolithus mcmurdoi.

Sapwood mycobiome varies across host, plant compartment and environments in Nothofagus forests from Northern Patagonia

Global forests are increasingly being threatened by altered climatic conditions and increased attacks by pests and pathogens. The complex ecological interactions among pathogens, microbial communities, tree hosts and the environment are important drivers of forest dynamics. Little is known about the ecology of forest pathology and related microbial communities in temperate forests of the southern hemisphere. In this study, we used next-generation sequencing to characterize sapwood-inhabiting fungal communities in North Patagonian Nothofagus forests and assessed patterns of diversity of taxa and ecological guilds across climatic, site and host variables (health condition and compartment) as a contribution to Nothofagus autecology. The diversity patterns inferred through the metabarcoding analysis were similar to those obtained through culture-dependent approaches. However, we detected additional heterogeneity and greater richness with culture-free methods. Host species was the strongest driver of fungal community structure and composition, while host health status was the weakest. The relative impacts of site, season, plant compartment and health status were different for each tree species; these differences can be interpreted as a matter of water availability. For Nothofagus dombeyi, which is distributed across a wide range of climatic conditions, site was the strongest driver of community composition. The microbiome of N. pumilio varied more with season and temperature, a relevant factor for forest conservation in the present climate change scenario. Both species carry a number of potential fungal pathogens in their sapwood, whether they exhibit symptoms or not. Our results provide insight into the diversity of fungi associated with the complex pathobiome of the dominant Nothofagus species in southern South America.

A new genus Neobelonopsis and two new species of Trichobelonium (Helotiales, Ascomycota) discovered mainly from poaceous grasses native to Asia in Japan

Mollisioid fungi, represented by Mollisia (Fr.) P. Karst., are characterized by soft, sessile apothecia with globose, dark-celled excipula, hyaline ascospores, and worldwide distribution in temperate regions. Their generic and species delimitation is difficult due to the lack of distinct features, and studies based on DNA sequences are urgently required. Two genera of mollisioid fungi, Belonopsis and Trichobelonium, comprise relatively few species and are recognized by (0-)1-3-septate ascospores, medullary excipulum composed of loosely interwoven hyphae, and calcium oxalate crystals in the excipulum. Specimens of undescribed species that are morphologically assignable to Belonopsis or Trichobelonium were collected from various sites in Japan and their assignment to the proper genera was attempted. According to a molecular phylogenetic analysis involving members of Mollisiaceae based on concatenated sequences of ITS, LSU, and RPB1, eight taxonomic entities were placed in a strongly supported single clade with Mollisiadiesbachiana, separated from the type species of Belonopsis, B.excelsior. A new genus Neobelonopsis was thus proposed to accommodate the undescribed species. In this study, eight new species of Neobelonopsis and two new species of Trichobelonium were described. A new combination was also proposed for M.diesbachiana. The generic distinction of Neobelonopsis and Trichobelonium was supported by molecular analysis. Some additional characteristics to delimit Trichobelonium were identified, such as the presence of anchoring hyphae between the base of the apothecium and subiculum, and the production of abundant crystals and soluble pigments on the colonies. Derivative species of Neobelonopsis were found to have multi-septa in ascospores.

Chemical Characterization and Metagenomic Identification of Endophytic Microbiome from South African Sunflower (Helianthus annus) Seeds

Helianthus annus (sunflower) is a globally important oilseed crop whose survival is threatened by various pathogenic diseases. Agrochemical products are used to eradicate these diseases; however, due to their unfriendly environmental consequences, characterizing microorganisms for exploration as biocontrol agents are considered better alternatives against the use of synthetic chemicals. The study assessed the oil contents of 20 sunflower seed cultivars using FAMEs-chromatography and characterized the endophytic fungi and bacteria microbiome using Illumina sequencing of fungi ITS 1 and bacteria 16S (V3-V4) regions of the rRNA operon. The oil contents ranged between 41-52.8%, and 23 fatty acid components (in varied amounts) were found in all the cultivars, with linoleic (53%) and oleic (28%) acids as the most abundant. Ascomycota (fungi) and Proteobacteria (bacteria) dominated the cultivars at the phyla level, while Alternaria and Bacillus at the genus level in varying abundance. AGSUN 5102 and AGSUN 5101 (AGSUN 5270 for bacteria) had the highest fungi diversity structure, which may have been contributed by the high relative abundance of linoleic acid in the fatty acid components. Dominant fungi genera such as Alternaria, Aspergillus, Aureobasidium, Alternariaste, Cladosporium, Penicillium, and bacteria including Bacillus, Staphylococcus, and Lactobacillus are established, providing insight into the fungi and bacteria community structures from the seeds of South Africa sunflower.

Analysis of endophyte diversity of two Gentiana plants species and the association with secondary metabolite

Background

The influence of external environmental factors on secondary metabolites of medicinal plants has always been studied. However, little is known about the relationships between endophytes and host metabolites, especially the relationship differences between different plant species. Thus, we used high-throughput sequencing methods to compare endophyte diversity from roots of two closely related species, Gentiana officinalis and G. siphonantha, from the same production area, and analyze the association with four secondary metabolites (Gentiopicroside, Loganic acid, Swertiamarine and Sweroside).

Results

The fungal and bacteria communities’ richness and diversity of G. siphonantha was higher than G. officinalis. Ascomycota and Proteobacteria were dominant fungal and bacterial phylum of the two closely related species. At the genus level, Tetracladium and Cadophora were dominant fungal genus in G. officinalis and G. siphonantha samples, respectively. While Pseudomonas was dominant bacterial genus in two closely related species, with relative abundances were 8.29 and 8.05%, respectively. Spearman analysis showed that the content of loganic acid was significantly positively correlated with endophytic fungi, the content of gentiopicroside, swertiamarine and sweroside were significantly positively correlated with endophytic bacteria in the two related species. PICRUSt and FUNGuild predictive analysis indicated that metabolism and saprotroph was primary function of endophytic bacteria and fungi in the two related species.

Conclusion

Our results will expand the knowledge on relationships of plant-microbe interactions and offer pivotal information to reveal the role of endophytes in the production of Gentiana plant and its important secondary metabolite.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02510-4.