Covering: up to December 2017 The diversity of secondary metabolites in the fungal order Xylariales is reviewed with special emphasis on correlations between chemical diversity and biodiversity as inferred from recent taxonomic and phylogenetic studies. The Xylariales are arguably among the predominant fungal endophytes, which are the producer organisms of pharmaceutical lead compounds including the antimycotic sordarins and the antiparasitic nodulisporic acids, as well as the marketed drug, emodepside. Many Xylariales are “macromycetes”, which form conspicuous fruiting bodies (stromata), and the metabolite profiles that are predominant in the stromata are often complementary to those encountered in corresponding mycelial cultures of a given species. Secondary metabolite profiles have recently been proven highly informative as additional parameters to support classical morphology and molecular phylogenetic approaches in order to reconstruct evolutionary relationships among these fungi. Even the recent taxonomic rearrangement of the Xylariales has been relying on such approaches, since certain groups of metabolites seem to have significance at the species, genus or family level, respectively, while others are only produced in certain taxa and their production is highly dependent on the culture conditions. The vast metabolic diversity that may be encountered in a single species or strain is illustrated based on examples like Daldinia eschscholtzii, Hypoxylon rickii, and Pestalotiopsis fici. In the future, it appears feasible to increase our knowledge of secondary metabolite diversity by embarking on certain genera that have so far been neglected, as well as by studying the volatile secondary metabolites more intensively. Methods of bioinformatics, phylogenomics and transcriptomics, which have been developed to study other fungi, are readily available for use in such scenarios.

A recent find of a Marasmius species in Northern Thailand led to the isolation of five unprecedented derivatives of the carotane antibiotic fulvoferruginin (1), fulvoferruginins B–F (2–6). The structures of these sesquiterpenoids were elucidated using HRESIMS, 1D and 2D NMR, as well as CD spectroscopy. Assessing the bioactivity, fulvoferruginin emerged as a potent cytotoxic agent of potential pharmaceutical interest.

Pseudopalawania siamensis gen. et sp. nov., from northern Thailand, is introduced based on multi-gene analyses and morphological comparison. An isolate was fermented in yeast malt culture broth and explored for its secondary metabolite production. Chromatographic purification of the crude ethyl acetate (broth) extract yielded four tetrahydroxanthones comprised of a new heterodimeric bistetrahydroxanthone, pseudopalawanone (1), two known dimeric derivatives, 4,4′-secalonic acid D (2) and penicillixanthone A (3), the corresponding monomeric tetrahydroxanthone paecilin B (4), and the known benzophenone, cephalanone F (5). Compounds 1–3 showed potent inhibitory activity against Gram-positive bacteria. Compounds 2 and 3 were inhibitory against Bacillus subtilis with minimum inhibitory concentrations (MIC) of 1.0 and 4.2 μg/mL, respectively. Only compound 2 showed activity against Mycobacterium smegmatis. In addition, the dimeric compounds 1–3 also showed moderate cytotoxic effects on HeLa and mouse fibroblast cell lines, which makes them less attractive as candidates for development of selectively acting antibiotics.

The tomato is a major crop worldwide and is one of the five most consumed vegetables in Germany. Stemphylium species including S. eturmiunum, S. gracilariae, S. lycii, S. lycopersici, S. rombundicum, S. simmonsii, S. solani, and S. vesicarium have been identified as tomato pathogens in various countries. In Germany, multiple instances of S. lycopersici and S. solani affecting tomato plants have been documented; however, only one incident of S. vesicarium has been reported in 1972. S. vesicarium is known to cause yellowish-brown spots on tomato leaves, which can ultimately lead to defoliation and reduced fruit yield. Therefore, it is crucial to identify the S. vesicarium that cause this disease accurately. In this study, S. vesicarium was isolated from necrotic tomato plants in organic farms located in northern and southern regions of Germany. Single spore isolates were generated and identified as S. vesicarium based on morphological characteristic and molecular analyses using nucleotide sequences of the internal transcribed spacer (ITS) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Koch´s postulates were fulfilled and revealed that S. vesicarium is the causal agent of brown spot on the samples adding a new account of the species.

Tomato (Solanum lycopersicum L.) is one of the most popular vegetables in Germany and the demand for organically grown tomatoes in particular is growing steadily. In seasonal low-cost organic tomat...

Synergistic interactions between soil-borne fungi and plant-parasitic nematodes can cause significantly more damage to a crop than either pathogen alone. For peppermint, synergistic interactions between Verticillium dahliae and plant-parasitic nematodes have only been described for the migratory endoparasite Pratylenchus, whereas there is no information for such interactions for ectoparasitic or sedentary endoparasitic nematodes. To determine whether species of these nematode groups co-occur with V. dahliae on peppermint, and to evaluate whether their interactions with V. dahliae on peppermint are synergistic, we conducted a field survey and three greenhouse experiments. In the field survey, we confirmed the presence of V. dahliae in infected plants and detected eight plant-parasitic nematode species in the soil associated with peppermint. Among the detected taxa were the sedentary endoparasite Meloidogyne hapla and the ectoparasite Paratylenchus projectus, with the latter found at particularly high densities. Both such species were selected for greenhouse experiments. The synergistic effect was assessed primarily on the basis of symptom severity and a measure of plant development. Furthermore, we employed isolation and qPCR to detect and quantify V. dahliae in peppermint stem base, stem and leaf samples. Results suggested potential synergistic interactions between V. dahliae and both nematodes, which was associated with increased wilt symptoms and reduced plant growth. The qPCR and isolation approaches confirmed the presence of V. dahliae and suggested that both nematodes influence V. dahliae distribution within a plant, as differences in Ct values between stem base and stem varied among treatments. In V. dahliae alone, no consistent differences were observed. In V. dahliae-M. hapla, Ct values were higher in the stem than in the stem base, whereas in V. dahliae-P. projectus, variable responses were observed depending on the inoculation order. In conclusion, the results demonstrated the cooccurrence of V. dahliae with different plant-parasitic nematodes on peppermint and indicated the potential synergistic interactions with M. hapla and P. projectus. However, whether such synergistic effects also occur under field conditions still needs to be proven.