Enhancing Biomass and ß-Glucan Yield from Oyster Mushroom Pleurotus ostreatus (Agaricomycetes) Mycelia through Extract Valorization.

This study aimed to examine the impact of mushroom extract-based solid media on the ß-glucan content, growth rate, density, and biomass content of Pleurotus ostreatus (oyster mushroom) mycelia. Fresh, high-quality raw P. ostreatus were washed, sliced, and heated in a sealed pressure cooker at 90°C for 4 h in the drying cabinet. Following the heating process, centrifugation was carried out. Different concentrations of Pleurotus ostreatus extract were mixed with distilled water (0%, 25%, 50%, 75%, and 100%) and prepared for a sterile solid media. A malt extract-based medium was maintained as a control. This study focuses on the growth performance of P. ostreatus mycelium on its own mushroom extract-based culture medium which holds considerable economic and environmental significance. During the six-day observation period, the mycelium exhibited consistent growth across all tested media, maintaining a steady growth rate of 15 mm. The increased content of mushroom extract resulted from the enhanced density of the mycelia and biomass content. It can be inferred that when media containing less than 25% of mushroom extract dilution is used, ß-glucan can be formed in smaller amounts. Further research is needed to explore mushroom extract derived from different types of mushroom byproducts, which fail to meet commercial standards.

A Phytotoxin with Selective Herbicidal Activity and Related Metabolites from the Phytopathogenic Fungus Bipolaris cookei SYBL03.

Weeds are a serious threat to crop production, and the utilization of secondary metabolites of phytopathogenic fungi is considered to be an effective method of weed control. In this study, eight compounds were isolated and purified from the mycelium and fermentation broth extracts of Bipolaris cookei SYBL03. The compounds (1-8), except 2 and 6, are reported for the first time from this genus. The herbicidal activities of compounds 1-8 were studied by evaluating their effects on the seed germination and seedling growth of monocotyledonous and dicotyledonous weeds. The results indicated that compound 7 (Cyclo-N-methylphenylalanyltryptophenyl, cNMPT) exhibited a concentration-dependent dual effect on the growth of weed seedlings and selective herbicidal activity against dicotyledonous weeds. We further investigated the morphological and physiological responses of roots of Amaranthus retroflexus, a dicotyledonous weed, to compound 7. Some changes were found in seedlings grown in 400 µg/mL compound 7 solution for 96 h, such as shortening and swelling of elongation zone cells, reduced number and length of root hairs, damage and wrinkling of the root surface, occurrence of electrolyte leakage, and an increase in ethylene content. These results suggest that compound 7 may exert herbicidal activity by causing stress to weed seedlings. Increased ethylene production could be involved in the response of plants to compound 7.

Bioactivities evaluation of an endophytic bacterial strain Bacillus tequilensis QNF2 inhibiting apple ring rot caused by Botryosphaeria dothidea on postharvest apple fruits.

Apple ring rot, one of the most common apple postharvest diseases during storage, is caused by Botryosphaeria dothidea. Presently, the disease management is primarily dependent on chemical fungicide application. Here we demonstrated an endophyte bacterium Bacillus tequilensis QNF2, isolated from Chinese leek (Allium tuberosum) roots considerably suppressed B. dothidea mycelial growth, with the highest suppression of 73.56 % and 99.5 % in the PDA and PDB medium, respectively in vitro confront experiments. In in vivo experiments, B. tequilensis QNF2 exhibited a control efficacy of 88.52 % and 100 % on ring rot disease on postharvest apple fruits inoculated with B. dothidea disc and dipped into B. dothidea culture, respectively. In addition, B. tequilensis QNF2 volatile organic compounds (VOCs) also manifested markedly inhibition against B. dothidea mycelial growth and the ring rot on postharvest apple fruits. Moreover, B. tequilensis QNF2 severely damaged the mycelial morphology of B. dothidea. Finally, B. tequilensis QNF2 significantly repressed the expression of six pathogenicity-related genes, such as adh, aldh, aldh3, galm, pdc1, pdc2, involved in glycolysis/gluconeogenesis of B. dothidea. The findings of the study proved that B. tequilensis QNF2 was a promising alternative for controlling apple ring rot of postharvest apple fruit.

Genome-wide identification and expression analysis revealed key transcription factors as potential regulators of high-temperature adaptation of Coriolopsis trogii.

Transcription factors (TFs) play a crucial role in gene expression, and studying them can lay the foundation for future research on the functional characterization of TFs involved in various biological processes. In this study, we conducted a genome-wide identification and analysis of TFs in the thermotolerant basidiomycete fungus, Coriolopsis trogii. The TF repertoire of C. trogii consisted of 350 TFs, with C2H2 and Zn2C6 being the largest TF families. When the mycelia of C. trogii were cultured on PDA and transferred from 25 to 35 °C, 14 TFs were up-regulated and 14 TFs were down-regulated. By analyzing RNA-seq data from mycelia cultured at different temperatures and under different carbon sources, we identified 22 TFs that were differentially expressed in more than three comparisons. Co-expression analysis revealed that seven differentially expressed TFs, including four Zn2C6s, one Hap4_Hap_bind, one HMG_box, and one Zinc_knuckle, showed significant correlation with 729 targeted genes. Overall, this study provides a comprehensive characterization of the TF family and systematically screens TFs involved in the high-temperature adaptation of C. trogii, laying the groundwork for further research into the specific roles of TFs in the heat tolerance mechanisms of filamentous fungi.

Comparative Transcriptomics of the Entomopathogenic Fungus Beauveria bassiana Grown on Aerial Surface and in Liquid Environment.

Beauveria bassiana, the causative agent of arthropod, proliferates in the host hemolymph (liquid environment) and shits to saprotrophic growth on the host cadaver (aerial surface). In this study, we used transcriptomic analysis to compare the gene expression modes between these two growth phases. Of 10,366 total predicted genes in B. bassiana, 10,026 and 9985 genes were expressed in aerial (AM) and submerged (SM) mycelia, respectively, with 9853 genes overlapped. Comparative analysis between two transcriptomes indicated that there were 1041 up-regulated genes in AM library when compared with SM library, and 1995 genes were down-regulated, in particular, there were 7085 genes without significant change in expression between two transcriptomes. Furthermore, of 25 amidase genes (AMD), BbAMD5 has high expression level in both transcriptomes, and its protein product was associated with cell wall in aerial and submerged mycelia. Disruption of BbAMD5 significantly reduced mycelial hydrophobicity, hydrophobin translocation, and conidiation on aerial plate. Functional analysis also indicated that BbAmd5 was involved in B. bassiana blastospore formation in broth, but dispensable for fungal virulence. This study revealed the high similarity in global expression mode between mycelia grown under two cultivation conditions.

Biocontrol Mechanisms of Three Plant Essential Oils Against Phytophthora infestans Causing Potato Late Blight.

Late blight, caused by the notorious pathogen Phytophthora infestans, poses a significant threat to potato (Solanum tuberosum) crops worldwide, impacting their quality as well as yield. Here, we aimed to investigate the potential use of cinnamaldehyde, carvacrol, and eugenol as control agents against P. infestans and to elucidate their underlying mechanisms of action. To determine the pathogen-inhibiting concentrations of these three plant essential oils (PEOs), a comprehensive evaluation of their effects using gradient dilution, mycelial growth rate, and spore germination methods was carried out. Cinnamaldehyde, carvacrol, and eugenol were capable of significantly inhibiting P. infestans by hindering its mycelial radial growth, zoospore release, and sporangium germination; the median effective inhibitory concentration of the three PEOs was 23.87, 8.66, and 89.65 µl/liter, respectively. Scanning electron microscopy revealed that PEOs caused the irreversible deformation of P. infestans, resulting in hyphal shrinkage, distortion, and breakage. Moreover, propidium iodide staining and extracellular conductivity measurements demonstrated that all three PEOs significantly impaired the integrity and permeability of the pathogen's cell membrane in a time- and dose-dependent manner. In vivo experiments confirmed the dose-dependent efficacy of PEOs in reducing the lesion diameter of potato late blight. Altogether, these findings provide valuable insight into the antifungal mechanisms of PEOs vis-à-vis late blight-causing P. infestans. By utilizing the inherent capabilities of these natural compounds, we could effectively limit the harmful impacts of late blight on potato crops, thereby enhancing agricultural practices and ensuring the resilience of global potato food production.

Rhein Inhibits Cell Development and Aflatoxin Biosynthesis via Energy Supply Disruption and ROS Accumulation in Aspergillus flavus.

Aspergillus flavus and its carcinogenic secondary metabolites, aflatoxins, not only cause serious losses in the agricultural economy, but also endanger human health. Rhein, a compound extracted from the Chinese herbal medicine Rheum palmatum L. (Dahuang), exhibits good anti-inflammatory, anti-tumor, and anti-oxidative effects. However, its effect and underlying mechanisms against Aspergillus flavus have not yet been fully illustrated. In this study, we characterized the inhibition effect of rhein on A. flavus mycelial growth, sporulation, and aflatoxin B1 (AFB1) biosynthesis and the potential mechanism using RNA-seq analysis. The results indicate that A. flavus mycelial growth and AFB1 biosynthesis were significantly inhibited by 50 µM rhein, with a 43.83% reduction in colony diameter and 87.2% reduction in AFB1 production. The RNA-seq findings demonstrated that the differentially expressed genes primarily participated in processes such as spore formation and development, the maintenance of cell wall and membrane integrity, management of oxidative stress, the regulation of the citric acid cycle, and the biosynthesis of aflatoxin. Biochemical verification experiments further confirmed that 50 µM rhein effectively disrupted cell wall and membrane integrity and caused mitochondrial dysfunction through disrupting energy metabolism pathways, leading to decreased ATP synthesis and ROS accumulation, resulting in impaired aflatoxin biosynthesis. In addition, a pathogenicity test showed that 50 µM rhein inhibited A. flavus spore growth in peanut and maize seeds by 34.1% and 90.4%, while AFB1 biosynthesis was inhibited by 60.52% and 99.43%, respectively. In conclusion, this research expands the knowledge regarding the antifungal activity of rhein and provides a new strategy to mitigate A. flavus contamination.

Antifungal efficacy of Bacillus amyloliquefaciens ZK-9 against Fusarium graminearum and analysis of the potential mechanism of its lipopeptides.

Fusarium graminearum is a destructive fungal pathogen that seriously threatens wheat production and quality. In the management of fungal infections, biological control is an environmentally friendly and sustainable approach. Here, the antagonistic strain ZK-9 with a broad antifungal activity was identified as Bacillus amyloliquefaciens. ZK-9 could produce extracellular enzymes such as pectinase, protease, cellulase, and amylase, as well as plant growth-promoting substances including IAA and siderophore. Lipopeptides extracted from strain ZK-9 had the high inhibitory effects on the mycelia of F. graminearum with the minimum inhibitory concentration (MIC) of 0.8 mg/mL. Investigation on the action mechanism of lipopeptides showed they could change the morphology of mycelia, damage the cell membrane, lower the content of ergosterol and increase the relative conductivity of membrane, cause nucleic acid and proteins leaking out from the cells, and disrupt the cell membrane permeability. Furthermore, metabolomic analysis of F. graminearum revealed the significant differences in the expression of 100 metabolites between the lipopeptides treatment group and the control group, which were associated with various metabolic pathways, mainly including amino acid biosynthesis, pentose, glucuronate and glycerophospholipid metabolism. In addition, strain ZK-9 inhibited Fusarium crown rot (FCR) with a biocontrol efficacy of 82.14 % and increased the plant height and root length by 24.23 % and 93.25 %, respectively. Moreover, the field control efficacy of strain ZK-9 on Fusarium head blight (FHB) was 71.76 %, and the DON content in wheat grains was significantly reduced by 69.9 %. This study puts valuable insights into the antifungal mechanism of lipopeptides against F. graminearum, and provides a promising biocontrol agent for controlling F. graminearum.

Comprehensive investigations of 2-phenylethanol production by the filamentous fungus Annulohypoxylon stygium.

2-Phenylethanol (2-PE) is an aromatic compound with a rose-like fragrance that is widely used in food and other industries. Yeasts have been implicated in the biosynthesis of 2-PE; however, few studies have reported the involvement of filamentous fungi. In this study, 2-PE was detected in Annulohypoxylon stygium mycelia grown in both potato dextrose broth (PDB) and sawdust medium. Among the 27 A. stygium strains investigated in this study, the strain "Jinjiling" (strain S20) showed the highest production of 2-PE. Under optimal culture conditions, the concentration of 2-PE was 2.33 g/L. Each of the key genes in Saccharomyces cerevisiae shikimate and Ehrlich pathways was found to have homologous genes in A. stygium. Upon the addition of L-phenylalanine to the medium, there was an upregulation of all key genes in the Ehrlich pathway of A. stygium, which was consistent with that of S. cerevisiae. A. stygium as an associated fungus provides nutrition for the growth of Tremella fuciformis and most spent composts of T. fuciformis contain pure A. stygium mycelium. Our study on the high-efficiency biosynthesis of 2-PE in A. stygium offers a sustainable solution by utilizing the spent compost of T. fuciformis and provides an alternative option for the production of natural 2-PE. KEY POINTS: • Annulohypoxylon stygium can produce high concentration of 2-phenylethanol. • The pathways of 2-PE biosynthesis in Annulohypoxylon stygium were analyzed. • Spent compost of Tremella fuciformis is a potential source for 2-phenylethanol.

Material Composition Characteristics of Aspergillus cristatus under High Salt Stress through LC-MS Metabolomics.

Aspergillus cristatus is a crucial edible fungus used in tea fermentation. In the industrial fermentation process, the fungus experiences a low to high osmotic pressure environment. To explore the law of material metabolism changes during osmotic pressure changes, NaCl was used here to construct different osmotic pressure environments. Liquid chromatography-mass spectrometry (LC-MS) combined with multivariate analysis was performed to analyze the distribution and composition of A. cristatus under different salt concentrations. At the same time, the in vitro antioxidant activity was evaluated. The LC-MS metabolomics analysis revealed significant differences between three A. cristatus mycelium samples grown on media with and without NaCl concentrations of 8% and 18%. The contents of gibberellin A3, A124, and prostaglandin A2 related to mycelial growth and those of arabitol and fructose-1,6-diphosphate related to osmotic pressure regulation were significantly reduced at high NaCl concentrations. The biosynthesis of energy-related pantothenol and pantothenic acid and antagonism-related fluvastatin, aflatoxin, and alternariol significantly increased at high NaCl concentrations. Several antioxidant capacities of A. cristatus mycelia were directly related to osmotic pressure and exhibited a significant downward trend with an increase in environmental osmotic pressure. The aforementioned results indicate that A. cristatus adapts to changes in salt concentration by adjusting their metabolite synthesis. At the same time, a unique set of strategies was developed to cope with high salt stress, including growth restriction, osmotic pressure balance, oxidative stress response, antioxidant defense, and survival competition.

Pseudomonas protegens volatile organic compounds inhibited brown rot of postharvest peach fruit by repressing the pathogenesis-related genes in Monilinia fructicola.

Brown rot, caused by Monilinia fructicola, is considered one of the devasting diseases of pre-harvest and post-harvest peach fruits, restricting the yield and quality of peach fruits and causing great economic losses to the peach industry every year. Presently, the management of the disease relies heavily on chemical control. In the study, we demonstrated that the volatile organic compounds (VOCs) of endophyte bacterial Pseudomonas protegens QNF1 inhibited the mycelial growth of M. fructicola by 95.35% compared to the control, thereby reducing the brown rot on postharvest fruits by 98.76%. Additionally, QNF1 VOCs severely damaged the mycelia of M. fructicola. RNA-seq analysis revealed that QNF1 VOCs significantly repressed the expressions of most of the genes related to pathogenesis (GO:0009405) and integral component of plasma membrane (GO:0005887), and further analysis revealed that QNF1 VOCs significantly altered the expressions of the genes involved in various metabolism pathways including Amino acid metabolism, Carbohydrate metabolism, and Lipid metabolism. The findings of the study indicated that QNF1 VOCs displayed substantial control efficacy by disrupting the mycelial morphology of M. fructicola, weakening its pathogenesis, and causing its metabolic disorders. The study provided a potential way and theoretical support for the management of the brown rot of peach fruits.

A cascade approach to sustainable agriculture: From mushroom mycelium to lettuce harvest.

Sustainable agriculture involves adopting best practices in food production to promote environmental and economic sustainability. Its implementation primarily aims to utilise organic residues to increase yield, diversify production, and reduce costs. In this context, the objective of this study was to investigate different substrates for Hypsizygus ulmarius production and, from its residual substrate, to develop formulations for lettuce seedling growth and subsequent greenhouse cultivation. For mushroom production, substrates were prepared from sawdust with the addition of wheat bran, rice bran, soybean meal, and calcite, resulting in four distinct substrate formulations. The spent mushroom substrate (SMS), obtained at the end of cultivation, was used for lettuce seedling production along with the commercial substrate Carolina Soil® and the soil conditioner BacSol®. The top five formulations were selected for transplanting in the greenhouse. Regarding mushroom production, substrates with higher carbon/nitrogen ratios, around 66: 1, resulted in higher yields. For seedling production, SMS showed lower efficiency compared to the commercial substrate Carolina Soil®, which also benefited from the addition of the soil conditioner BacSol®. However, after transplanting lettuce seedlings, the formulation containing SMS showed superior results in almost all evaluated parameters. Therefore, we concluded that despite the inefficiency of using H.ulmarius SMS for lettuce seedling production, it favours the establishment of seedlings in greenhouse cultivation environments.

Biological Characteristics of the Mycelium and Optimization of the Culture Medium for Phallus dongsun.

This study aimed to elucidate the influence of various culture medium components, including carbon sources, nitrogen sources, inorganic salts, suspension agents, and temperature, on the mycelial growth characteristics of Phallus dongsun. Employing single-factor experiments and response surface methodology within glass Petri dishes, the research identified that carrot powder, soybean powder, and ZnSO4 notably enhanced the proliferation of aerial mycelium, significantly augmenting the growth rate of P. dongsun mycelium. The resultant mycelium was observed to be dense, robust, and fluffy in texture. In particular, ZnSO4 markedly accelerated the mycelium growth rate. Furthermore, xanthan gum was found to effectively modulate the medium's viscosity, ensuring a stable suspension and facilitating nutrient equilibrium. The optimal cultivation temperature was determined to be 25°C, with mycelial growth ceasing below 5°C and mycelium perishing at temperatures exceeding 35°C. The optimal medium composition was established as follows: wheat starch 5 g/l, carrot powder 5 g/l, soybean powder 7.50 g/l, glucose 10 g/l, ZnSO4 0.71 g/l, NH4Cl 0.68 g/l, xanthan gum 0.5 g/l, and agar 20 g/l. Under these optimized conditions, the mycelium of P. dongsun exhibited a rapid growth rate (1.04 ± 0.14 mm/day), characterized by a thick, dense, and well-developed structure. This investigation provides a theoretical foundation for the conservation, strain selection, and breeding of P. dongsun.

[Filamentous morphology: a new frontier for genetic modification of filamentous fungal cell factories].

Filamentous fungi are a group of eukaryotic microorganisms widely found in nature. Some filamentous fungi have been developed as "cell factories" and extensively used for the production of recombinant proteins, organic acids, and secondary metabolites due to their strong protein secretion capabilities or effective synthesis of many natural products. The growth morphology of filamentous fungi significantly influences the quality and quantity of fermented products. Previous research conducted by the authors' group revealed that an increase in hyphal branches leads to enhanced protein secretion during liquid fermentation. With the development of morphological engineering of filamentous fungi, an increasing number of studies have focused on modifying fungal mycelium morphology to improve the yield of target metabolites during fermentation. While there have been a few reviews on the relationship between fungal fermentation morphology and productivity, research in this area is rapidly developing and requires updates. The paper presents a comprehensive review of domestic and international research reports, along with the authors' own research findings, to systematically review the morphological patterns of filamentous fungi, the impact of fungal morphology on industrial fermentation, as well as methods and strategies for regulating mycelial morphology. The aim of this review is to enhance the understanding of relevant domestic scholars regarding the morphological development of filamentous fungi and provide ideas for the rational engineering of fungal strains suitable for industrial fermentation.

Optimizing liquid fermentation for Wolfiporia cocos: gene expression and biosynthesis of pachymic acid and mycelial biomass.

Wolfiporia cocos, a versatile fungus acclaimed for its nutritional and therapeutic benefits in Traditional Chinese Medicine, holds immense potential for pharmaceutical and industrial applications. In this study, we aimed to optimize liquid fermentation techniques and culture medium composition to maximize mycelial biomass (MB) yield, pachymic acid (PA) concentration, and overall PA production. Additionally, we investigated the molecular basis of our findings by quantifying the expression levels of genes associated with PA and MB biosynthesis using quantitative real-time polymerase chain reaction. Under the optimized fermentation conditions, significant results were achieved, with maximum MB reaching 6.68 g l-1, PA content peaking at 1.25 mg g-1, and a total PA yield of 4.76 g l-1. Notably, among the four examined genes, squalene monooxygenase, exhibited enhanced expression at 0.06 ratio under the optimized conditions. Furthermore, within the realm of carbohydrate-active enzymes, the glycoside hydrolases 16 family displayed elevated expression levels at 21 ratios, particularly during MB production. This study enhances understanding of genetic mechanism governing MB and PA production in W. cocos, highlighting the roles of squalene monooxygenase and glycoside hydrolases 16 carbohydrate-active enzymes.

Biological characteristics and metabolic phenotypes of different anastomosis groups of Rhizoctonia solani strains.

BACKGROUND: Rhizoctonia solani is an important plant pathogen worldwide, and causes serious tobacco target spot in tobacco in the last five years. This research studied the biological characteristics of four different anastomosis groups strains (AG-3, AG-5, AG-6, AG-1-IB) of R. solani from tobacco. Using metabolic phenotype technology analyzed the metabolic phenotype differences of these strains. RESULTS: The results showed that the suitable temperature for mycelial growth of four anastomosis group strains were from 20 to 30oC, and for sclerotia formation were from 20 to 25oC. Under different lighting conditions, R. solani AG-6 strains produced the most sclerotium, followed by R. solani AG-3, R. solani AG-5 and R. solani AG-1-IB. All strains had strong oligotrophic survivability, and can grow on water agar medium without any nitrutions. They exhibited three types of sclerotia distribution form, including dispersed type (R. solani AG-5 and AG-6), peripheral type (R. solani AG-1-IB), and central type (R. solani AG-3). They all presented different pathogenicities in tobacco leaves, with the most virulent was noted by R. solani AG-6, followed by R. solani AG-5 and AG-1-IB, finally was R. solani AG-3. R. solani AG-1-IB strains firstly present symptom after inoculation. Metabolic fingerprints of four anastomosis groups were different to each other. R. solani AG-3, AG-6, AG-5 and AG-1-IB strains efficiently metabolized 88, 94, 71 and 92 carbon substrates, respectively. Nitrogen substrates of amino acids and peptides were the significant utilization patterns for R. solani AG-3. R. solani AG-3 and AG-6 showed a large range of adaptabilities and were still able to metabolize substrates in the presence of the osmolytes, including up to 8% sodium lactate. Four anastomosis groups all showed active metabolism in environments with pH values from 4 to 6 and exhibited decarboxylase activities. CONCLUSIONS: The biological characteristics of different anastomosis group strains varies, and there were significant differences in the metabolic phenotype characteristics of different anastomosis group strains towards carbon source, nitrogen source, pH, and osmotic pressure.

The critical roles of the Zn2Cys6 transcription factor Fp487 in the development and virulence of Fusarium pseudograminearum: A potential target for Fusarium crown rot control.

Fusarium crown rot (FCR) caused by Fusarium pseudograminearum poses a significant threat to wheat production in the Huang-Huai-Hai region of China. However, the pathogenic mechanism of F. pseudograminearum is still poorly understood. Zn2Cys6 transcription factors, which are exclusive to fungi, play pivotal roles in regulating fungal development, drug resistance, pathogenicity, and secondary metabolism. In this study, we present the functional characterization of a Zn2Cys6 transcription factor F. pseudograminearum, designated Fp487. In F. pseudograminearum, Fp487 is shown to be required for mycelial growth through gene knockout and phenotypic analyses. Compared with wild-type CF14047, the ∆Fp487 mutant displayed a slight reduction in growth rate but a significant decrease in conidiogenesis, pathogenicity and 3-acetyl-deoxynivalenol (3AcDON) production. Moreover, the mutant exhibited heightened sensitivity to oxidative and cytomembrane stress. Furthermore, we synthesized dsRNA from the Fp487 gene in vitro, resulting in a reduction in the growth rate of F. pseudograminearum and its virulence on barley leaves through spray-induced gene silencing (SIGS). Notably, this study makes the first instance of inducing the expression of abundant dsRNA from F. pseudograminearum by engineering the Escherichia coli strain HT115 (DE3) and utilizing the SIGS technique to evaluate the virulence effect of dsRNA on F. pseudograminearum. In conclusion, our findings revealed the crucial role of Fp487 in regulating pathogenicity, stress responses, DON production, and conidiogenesis in F. pseudograminearum. Furthermore, Fp487 is a potential RNAi-based target for FCR control.

Yeasts volatile organic compounds (VOCs) as potential growth enhancers and molds biocontrol agents of mushrooms mycelia.

Volatile organic compounds (VOCs) produced by yeasts can positively affect crops, acting as antifungals or biostimulants. In this study, Aureobasidium pullulans and Metschnikowia pulcherrima were evaluated as potential antagonists of Trichoderma spp., common fungal pathogen in mushroom cultivation. To assess the biocontrol ability and biostimulant properties of the selected yeast species, in vitro co-culture and VOCs exposure assays were conducted. In both assays, VOCs produced by Aureobasidium spp. showed the stronger antifungal activity with a growth inhibition up to 30 %. This result was further confirmed by the higher volatilome alcohol content revealed by solid phase microextraction-gas chromatography mass spectrometry (SPME/GC-MS). Overall, Aureobasidium strains can be potentially used as biocontrol agent in Pleorotus ostreatus and Cyclocybe cylindracea mycelial growth, without affecting their development as demonstrated by VOCs exposure assay and Fourier-transform infrared spectroscopy (FT-IR). Conversely, M. pulcherrima was characterized by a lower or absent antifungal properties and by a volatilome composition rich in isobutyl acetate, an ester often recognized as plant growth promoter. As confirmed by FT-IR, Lentinula mycelia exposed to M. pulcherrima VOCs showed a higher content of proteins and lipids, suggesting an improvement of some biochemical properties. Our study emphasizes that VOCs produced by specific yeast strains are potentially powerful alternative to synthetic fungicide in the vegetative growth of mushroom-forming fungi and also able to modify their biochemical composition.

Transcriptome analysis reveals the humic acids and chitosan suppressing Alternaria solani growth.

AIMS: Understanding the inhibitory effects of natural organic substances on soil-borne pathogenic fungi and the relevant molecular mechanisms are highly important for future development of green prevention and control technology against soil-borne diseases. Our study elucidates the inhibitory effect of the combined application of humic acids (HAs) and chitosan on Alternariasolani and the light on the corresponding mechanism. METHODS AND RESULTS: The effect on A. solani growth by HAs incorporated with chitosan was investigated by plate culture and the corresponding mechanism was revealed using transcriptomics. The colony growth of A. solani was suppressed with the highest inhibition rate 33.33% when swine manure HAs was compounded with chitosan at a ratio of 1:4. Chitosan changed the colony morphology from round to irregularly. RNA-seq in the HAs and chitosan (HC) treatment revealed 239 differentially expressed genes compared with the control. The unigenes associated with enzymes activities related to growth and biological processes closely related to mycelial growth and metabolism were downregulated. RNA-seq also revealed that chitosan altered the expression of genes related to secondary metabolism, fungal cell wall formation and polysaccharide synthesis, and metabolism. Meanwhile, weighted gene co-expression network analysis showed that, genes expression in the module positively correlated with mycelial growth was significantly reduced in the HC treatment; and the results were verified by real-time quantitative polymerase chain reaction. CONCLUSIONS: The co-inhibition effect of HAs and chitosan on A. solani is associated with downregulated genes expression correlated with mycelial growth.

Comparative metabolic profiling of the mycelium and fermentation broth of Penicillium restrictum from Peucedanum praeruptorum rhizosphere.

Microorganisms in the rhizosphere, particularly arbuscular mycorrhiza, have a broad symbiotic relationship with their host plants. One of the major fungi isolated from the rhizosphere of Peucedanum praeruptorum is Penicillium restrictum. The relationship between the metabolites of P. restrictum and the root exudates of P. praeruptorum is being investigated. The accumulation of metabolites in the mycelium and fermentation broth of P. restrictum was analysed over different fermentation periods. Non-targeted metabolomics was used to compare the differences in intracellular and extracellular metabolites over six periods. There were significant differences in the content and types of mycelial metabolites during the incubation. Marmesin, an important intermediate in the biosynthesis of coumarins, was found in the highest amount on the fourth day of incubation. The differential metabolites were screened to obtain 799 intracellular and 468 extracellular differential metabolites. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the highly enriched extracellular metabolic pathways were alanine, aspartate and glutamate metabolism, glyoxylate and dicarboxylate metabolism, and terpenoid backbone biosynthesis. In addition, the enrichment analysis associated with intracellular and extracellular ATP-binding cassette transporter proteins revealed that some ATP-binding cassette transporters may be involved in the transportation of certain amino acids and carbohydrates. Our results provide some theoretical basis for the regulatory mechanisms between the rhizosphere and the host plant and pave the way for the heterologous production of furanocoumarin.