Diversity and distribution of tropical ectomycorrhizal fungi

The tropics were long considered to have few ectomycorrhizal fungi, presumably due to a paucity of ectomycorrhizal host plants relative to higher-latitude ecosystems. However, an increase in research in tropical regions over the past 30 years has greatly expanded knowledge about the occurrence of tropical ectomycorrhizal fungi. To assess their broad biogeographic and diversity patterns, we conducted a comprehensive review and quantitative data analysis of 49 studies with 80 individual data sets along with additional data from GlobalFungi to elucidate tropical diversity patterns and biogeography of ectomycorrhizal fungi across the four main tropical regions: the Afrotropics, the Neotropics, Southeast Asia, and Oceania. Generalized linear models were used to explore biotic and abiotic influences on the relative abundance of the 10 most frequently occurring lineages. We also reviewed the available literature and synthesized current knowledge about responses of fungi to anthropogenic disturbances, and their conservation status and threats. We found that /russula-lactarius and /tomentella-thelephora were the most abundant lineages in the Afrotropics, the Neotropics, and Southeast Asia, whereas /cortinarius was the most abundant lineage in Oceania, and that /russula-lactarius, /inocybe, and /tomentella-thelephora were the most species-rich lineages across all of the tropical regions. Based on these analyses, we highlight knowledge gaps for each tropical region. Increased sampling of tropical regions, collaborative efforts, and use of molecular methodologies are needed for a more comprehensive view of the ecology and diversity of tropical ectomycorrhizal fungi.

The production of broad-spectrum antibiotics from phytopathogen Epicoccum sorghinum by culturing in host edible mushroom Thelephora ganbajun extract

Metabolism of special endophytes and phytopathogens can be induced by the symbiotic interactions with the host. A phytopathogen Epicoccum sorghinum cultured in host mushroom Thelephora ganbajun medium exhibited different metabolites compared with that of ordinary medium. An unprecedented scaffold possessing the same substructure as perylenequinone mycotoxin, a first methyl rearrangement product of phytotoxin, epoxydon 6-methylsalicylate ester, three undescribed compounds, and an undescribed natural product were isolated from E. sorghinum cultured in T. ganbajun. Episorin A and epicosorin A were produced from E. sorghinum induced by culturing in host medium. Episorin A was the first example of perylenequinone analogue in the natural products. These induced compounds and other metabolites showed notable antibiosis against endogenous fungi, and insect existing in mushroom. Induced episorin A showed significant inhibitory effects on nitric oxide production in LPS-activated macrophages, and anti-acetylcholinesterase with the IC₅₀ at 5.40 ± 0.25 μM, and 4.32 μM, respectively, and cytotoxicity against HL-60, A-549, SMMC-7721, MCF-7 and SW480 with IC₅₀ at 14.21 ± 0.53, 17.93 ± 0.22, 18.17 ± 0.63, 28.36 ± 0.43, and 18.20 ± 1.03 μM.

Complete mitochondrial genome of the edible Basidiomycete mushroom Thelephora aurantiotincta (Aphyllophorales: Thelephoraceae) from China

The complete mitochondrial genome of Thelephora aurantiotincta, an edible Basidiomycete mushroom species with ecological and economic value is reported in this study. The whole genome is a circular molecule 50,672 bp in length and encodes 42 genes as follows: 15 protein-coding genes, two rRNA genes and 25 tRNA genes. The A, T, C, G contents in the genome are 35.60%, 35.31%, 13.89%, and 15.20%, respectively. Phylogenetic analysis revealed a close relationship between T. aurantiotincta and T. ganbajun. This is the first complete mitochondrial genome for T. aurantiotincta that will be useful for providing basic genetic information for this important species.

Mycorrhizal divergence and selection against immigrant seeds in forest and dune populations of the partially mycoheterotrophic Pyrola rotundifolia

Plant populations occupying different habitats may diverge from each other over time and gradually accumulate genetic and morphological differences, ultimately resulting in ecotype or even species formation. In plant species that critically rely on mycorrhizal fungi, differences in mycorrhizal communities can contribute to ecological isolation by reducing or even inhibiting germination of immigrant seeds. In this study, we investigated whether the mycorrhizal communities available in the soil and associating with the roots of seedlings and adult plants of the partially mycoheterotrophic Pyrola rotundifolia differed between populations growing in sand dunes and forests. In addition, reciprocal germination experiments were performed to test whether native seeds showed higher germination than immigrant seeds. Our results showed that the mycorrhizal communities differed significantly between forest and dune populations, and that within populations seedlings and adults also associated with different mycorrhizal communities. In both forest and dune populations, mycorrhizal communities were dominated by members of the Thelephoraceae, but dune populations showed a higher incidence of members of the Inocybaceae, whereas forest populations showed a high abundance of members of the Russulaceae. Reciprocal germination experiments showed that native seeds showed a higher germination success than immigrant seeds and this effect was most pronounced in dune populations. Overall, these results demonstrate that plants of P. rotundifolia growing in dune and forest habitats associate with different mycorrhizal communities and that reduced germination of non-native seeds may contribute to reproductive isolation. We conclude that selection against immigrants may constitute an important reproductive barrier at early stages of the speciation process.

New species of Tomentella (Thelephorales) from the Patagonian Andes forests

The genus Tomentella forms abundant ectomycorrhizae in coniferous and deciduous forests worldwide. Molecular identification of root tips suggests undescribed species in the Nothofagus forests of Patagonia, Argentina. Tomentella tenuissima, T. pulvinulata and T. patagonica are described here as new to science based on morphological and molecular analyses. Their host range is addressed using available soil sequences. The identity of previous records of T. galzinii and T. radiosa are discussed with morphological and molecular evidence.

Symbiotic germination and development of myco-heterotrophic plants in nature: ontogeny of Corallorhiza trifida and characterization of its mycorrhizal fungi

The processes of symbiotic germination and seedling development were analysed in the myco-heterotrophic orchid Corallorhiza trifida, seeds of which were buried in 'packets' either adjacent to or at varying distances from adult plants in defined communities of ectomycorrhizal tree species. Germination occurred within eight months of burial under Betula-Alnus and within seven months under Salix repens. It was always associated with penetration of the suspensor by a clamp-forming mycorrhizal fungus. Four distinct developmental stages were defined and the rates of transition through these stages were plotted. There was no evidence of a relationship between extent of germination or rate of development and the presence of naturally distributed plants of C. trifida at the spatial scale of 1 m. The best germination and the most rapid rate of development of C. trifida seedlings occurred in a Salix repens community located at a considerable distance from any extant C. trifida population. Determination of internal transcribed spacer (ITS) RFLPs and of gene sequences of the fungi involved in symbiotic germination and growth of C. trifida, revealed them to belong exclusively to the Thelephora-Tomentella complex of the Thelephoraceae. These fungi are known also to be ectomycorrhizal associates of trees. It is hypothesized that the rate of growth of the C. trifida seedlings is determined by the ability of the fungal symbionts to transfer carbon from their ectomycorrhizal co-associates.