SummaryFungi (Eumycota) form close associations with plants, with which they have co-existed since the dawn of life on land, but their diversity in early terrestrial ecosystems is still poorly understood.We studied petrographic sections of exceptionally well-preserved petrified plants from the 407 million yr-old Rhynie Chert (Scotland, UK). For comparative purposes, we illustrate fungal associations in four extant lower land plants.We document two new endophytes in the plant Horneophyton lignieri: Palaeoglomus boullardii (sp. nov. Glomeromycota) colonizes parenchyma in a discontinuous zone of the outer cortex of the aerial axes, forming arbuscule-like structures, vesicles and spores; Palaeoendogone gwynne-vaughaniae (gen. nov., sp. nov. Mucoromycotina) colonizes parenchyma in the basal part of the plant, where it is present in intercellular spaces and as intracellular coils but absent from rhizoids.Critical comparisons between the newly discovered Horneophyton endophytes, fungi previously described from the Rhynie Chert and fungal colonization in extant lower land plants reveal several features characteristic of both Mucoromycotina and Glomeromycota. A reappraisal of fungal associations in early land plants indicates that they are more diverse than assumed hitherto, overturning the long-held paradigm that the early endophytes were exclusively Glomeromycota.

Background: Inonotus obliquus, also known as Chaga, is a parasitic fungus growing on birches and used in traditional medicine (especially by Khanty people) to treat various health problems. In this study, we aimed to quantify the 3 metabolites frequently cited in literature, that is, betulin, betulinic acid, and inotodiol in the Chaga recently discovered in forests located in Normandy (France), and to compare their concentrations with Ukrainian and Canadian Chaga. This study also explores the cytotoxicity of the French Chaga against cancer-derived cells and transformed cells. Methods: A quantification method by HPLC-MS-MS (high-performance liquid chromatography–tandem mass spectrometry) of betulin, betulinic acid, and inotodiol was developed to study the French Chaga and compare the concentration of these metabolites with extracts provided from Chaga growing in Canada and Ukraine. This method was also used to identify and quantify those 3 compounds in other traditional preparations of Chaga (aqueous extract, infusion, and decoction). Among these preparations, the aqueous extract that contains betulin, betulinic acid, and inotodiol was chosen to evaluate and compare its cytotoxic activity toward human lung adenocarcinoma cells (A549 line) and human bronchial epithelial cells (BEAS-2B line). Results: French Chaga contains betulin and betulinic acid at higher levels than in other Chaga, whereas the concentration of inotodiol is greater in the Canadian Chaga. Moreover, the results highlighted a cytotoxic activity of the Chaga’s aqueous extract after 48 and 72 hours of exposure with a higher effect on cancer-derived cells A549 than on normal transformed cells BEAS-2B (P = 0.025 after 48 hours of exposure and P = 0.004 after 72 hours of exposure).

Thin sections of petrified fossils made during the latter part of the nineteenth and early twentieth centuries to investigate the internal tissue systems of plants now provide an important new source of information on associated micro-organisms. We report a new heterokont eukaryote (Combresomyces williamsonii sp. nov.) based on exquisitely preserved fossil oogonia, antheridia and hyphae from the Carboniferous (Pennsylvanian: Bashkirian stage) of UK. The structure of the oogonia and antheridia and features observed within the hyphae demonstrate a relationship with Oomycetes (Peronosporomycetes). The fossil microorganism was documented in situ in petrified stem cortex and rootlets of the extinct seed fern Lyginopteris oldhamia (Pteridospermales). The main observed features point towards a pythiaceous Oomycete but links to biotrophic Albuginales or Peronosporaceae cannot be ruled out owing to the observation of a possible haustorium. Our study provides the earliest evidence for parasitism in Oomycetes.

Air quality can be altered by fungal contaminants suspended in the air, forming bioaerosols. Aspergilli section Nidulantes series Versicolores are recurrent in bioaerosols and are mainly responsible for allergies and asthma aggravation. Phylogenetic studies recently identified 12 new species within this series. This study is the first to identify species of Aspergillus series Versicolores in French bioaerosols and to characterize them macroscopically, microscopically and molecularly. Bioaerosols were collected in a cancer treatment center, in contaminated homes and in agricultural environments. A total of 93 isolates were cultured on selective media, observed by optical microscopy and identified by benA amplification before sequencing. The field data (temperature and relative humidity) were statistically tested to explore the ecology of these species. Eight species were identified from bioaerosols: Aspergillus creber and A. jensenii, which represent more than 80% of the isolates, and A. protuberus, A. puulaauensis, A. sydowii, A. tabacinus, A. amoenus and A. fructus. Aspergilli series Versicolores are distributed differently depending on the sampling site and climatic determinants. Aspergillus protuberus was found in bioaerosols collected under significantly lower relative humidity (p = 3.899 × 10−4). Characterization and repartition of these isolates belonging to the Versicolores series constitute an important step to better assess exposure to fungal bioaerosols.