Fungi and oomycetes release volatiles into their environment which could be used for olfactory detection and identification of these organisms by electronic-nose (e-nose). The aim of this study was to survey volatile compound emission using an e-nose device and to identify released molecules through solid phase microextraction–gas chromatography/mass spectrometry (SPME–GC/MS) analysis to ultimately develop a detection system for fungi and fungi-like organisms. To this end, cultures of eight fungi (Armillaria gallica, Armillaria ostoyae, Fusarium avenaceum, Fusarium culmorum, Fusarium oxysporum, Fusarium poae, Rhizoctonia solani, Trichoderma asperellum) and four oomycetes (Phytophthora cactorum, P. cinnamomi, P. plurivora, P. ramorum) were tested with the e-nose system and investigated by means of SPME-GC/MS. Strains of F. poae, R. solani and T. asperellum appeared to be the most odoriferous. All investigated fungal species (except R. solani) produced sesquiterpenes in variable amounts, in contrast to the tested oomycetes strains. Other molecules such as aliphatic hydrocarbons, alcohols, aldehydes, esters and benzene derivatives were found in all samples. The results suggested that the major differences between respective VOC emission ranges of the tested species lie in sesquiterpene production, with fungi emitting some while oomycetes released none or smaller amounts of such molecules. Our e-nose system could discriminate between the odors emitted by P. ramorum, F. poae, T. asperellum and R. solani, which accounted for over 88% of the PCA variance. These preliminary results of fungal and oomycete detection make the e-nose device suitable for further sensor design as a potential tool for forest managers, other plant managers, as well as regulatory agencies such as quarantine services.

The protective effects of Trichoderma asperellum IZR D-11 as a biocontrol agent against the powdery mildew Erysiphe alphitoides infecting leaves of Quercus robur were evaluated for the first time. A strain of Trichoderma had earlier been isolated in Belarus, and was identified in this study as T. asperellum by sequencing of three genomic markers: internal transcribed spacer, translation elongation factor 1 alpha and RNA polymerase II subunit 2, with over 99.2% identity to corresponding genomic sequences in GenBank. When applied once in the first year just after onset of powdery mildew disease, T asperellum IZR D-11 reduced disease progression and continued to reduce powdery mildew levels during the following three years. Photosynthetic activity as represented by chlorophyll fluorescence measured in oak seedlings was increased in treated plants, and greater assimilate production was also found. The use of this antagonistic fungus increased the total water content in oak leaves suggesting that T. asperellum IZR D-11 can serve as a preventive measure to reduce energy losses in the process of water transpiration. GC-MS analysis detected 49 volatile compounds in the headspace of pure cultures of T. asperellum. Sesquiterpenes represented mainly by daucene, dauca-4(11),8-diene and isodaucene were the largest group of compounds emitted. We speculate that these volatiles from T. asperellum IZR D-11 may be involved in induced resistance in the plant, but further research is needed. The above results suggest that T. asperellum strain IZR D-11 has potential as a biocontrol agent of oak powdery mildew in forest nurseries.

Fusarium graminearum and F. culmorum are considered some of the most dangerous pathogens of plant diseases. They are also considerably dangerous to humans as they contaminate stored grain, causing a reduction in yield and deterioration in grain quality by producing mycotoxins. Detecting Fusarium fungi is possible using various diagnostic methods. In the manuscript, qPCR tests were used to determine the level of wheat grain spoilage by estimating the amount of DNA present. High-performance liquid chromatography was performed to determine the concentration of DON and ZEA mycotoxins produced by the fungi. GC-MS analysis was used to identify volatile organic components produced by two studied species of Fusarium. A custom-made, low-cost, electronic nose was used for measurements of three categories of samples, and Random Forests machine learning models were trained for classification between healthy and infected samples. A detection performance with recall in the range of 88–94%, precision in the range of 90–96%, and accuracy in the range of 85–93% was achieved for various models. Two methods of data collection during electronic nose measurements were tested and compared: sensor response to immersion in the odor and response to sensor temperature modulation. An improvement in the detection performance was achieved when the temperature modulation profile with short rectangular steps of heater voltage change was applied.

Application of substances from medicinal mushrooms is one of the interesting approaches to improve cancer therapy. In this study, we commenced a new attempt in the field of Heterobasidion annosum (Fr.) Bref. sensu lato to further extend our knowledge on this basidiomycete fungus. For this purpose, analysis of the active substances of Heterobasidion annosum methanolic extract and also its influence on colorectal cancer in terms of in vitro and in vivo experiments were performed. In vivo studies on mice were conducted to verify its acute toxicity and to further affirm its anticancer potential. Results indicated that all the most common substances of best known medicinal mushrooms that are also responsible for their biological activity are present in tested extracts. In vitro tests showed a high hemocompatibility and a significant decrease in viability and proliferation of DLD-1 cells in a concentration-dependent manner of Heterobasidion annosum extract. The studies performed on xenograft model of mice showed lower tendency of tumor growth in the group of mice receiving Heterobasidion annosum extract as well as mild or moderate toxicity. Obtained results suggest beneficial potential of Heterobasidion annosum against colon cancer as cytotoxic agent or as adjuvant anticancer therapy.

The purpose of this study was to better understand the interactive impact of two soil-borne pathogens, Phytophthora cactorum and Armillaria gallica, on seedlings of silver birch (Betula pendula Roth.) subjected to stress caused by mechanical defoliation, simulating primary insect feeding. This is the first experimental confirmation of silver birch seedling root damage (and in consequence shoot mortality) caused by the additive effect of defoliation stress and P. cactorum inoculation via soil. However, the most severe damage to roots occurred after A. gallica inoculation. One year after treatments, chlorophyll fluorescence measurement, and gas chromatography coupled with mass spectrometry (GC-MS) were used to analyze the photosynthetic activity in leaves, the volatile organic compounds (VOCs) emitted by the birch leaves, and chemical compounds from the roots. The cumulative effect of the two pathogens and partial defoliation reduced photosynthetic activity, suggesting dysfunction of photosystem PSII due to the applied stresses. In summary, it seems that the main differences in photosynthetic performance could be attributed to Armillaria infection. The birch leaves in seedlings exposed to 50% defoliation, and inoculation with P.cactorum and A. gallica, emitted more aromatic carbonyls and alcohols, as well as half as much aliphatic esters, compared to controls. In infected birch roots, the production of phenols, triterpenes, and fatty alcohols increased, but fatty acids decreased. Higher levels of aromatic carbonyls and alcohols in leaves, as well as phenolic compounds in the roots of stressed birches (compared to control) suggest an activation of plant systemic acquired resistance (SAR).

The European Fraxinus species are threatened by the alien invasive pathogen Hymenoscyphus fraxineus, which was introduced into Poland in the 1990s and has spread throughout the European continent, causing a large-scale decline of ash. There are no effective treatments to protect ash trees against ash dieback, which is caused by this pathogen, showing high variations in susceptibility at the individual level. Earlier studies have shown that the application of phosphites could improve the health of treated seedlings after artificial inoculation with H. fraxineus. Three-year-old F. excelsior seedlings were inoculated with the following pathogens: a H. fraxineus, Phytophthora species mixture (P. plurivora, P. megasperma, and P. taxon hungarica), in combination with two pathogens and mock-inoculated as the control, and then either watered or treated with ammonium phosphite (Actifos). Results showed significant differences in the survival of seedlings and symptoms of disease development among the treatments. Chlorophyll-a fluorescence parameters indicated a decrease in photosynthetic efficiency in infected plants, suggesting that they were under strong biotic stress, but none of the parameters could be used as a reliable bioindicator for ash decline disease. The application of Actifos enhanced the production of triterpenes (ursolic and oleanolic acid), and decreased the production of phenols (tyrosol) and sterols (β-sitosterol) in seedlings infected with H. fraxineus. Treatment with Actifos caused seedlings to enhance their response to pathogen(s) attack and increase their survival probability.