Acetylation of Sesquiterpenyl Epoxy-Cyclohexenoids Regulates Fungal Growth, Stress Resistance, Endocytosis, and Pathogenicity of Nematode-Trapping Fungus Arthrobotrys oligospora via Metabolism and Transcription

Thermophilic fungus uses anthraquinones to modulate ferrous excretion, sterol-mediated endocytosis, and iron storage in response to cold stress

To date, there are no real physiological mechanisms for iron excretion in eukaryote, and no physiological "actuator" that can control all the three fundamental biologic processes of absorption, storage, and excretion. Here, we observed that the accumulation of anthraquinones by Thermomyces dupontii under cold stress can achieve this process. Through mutation analysis, we found that mutant ΔAn deficiency in anthraquinones accumulated ferrous and total free iron due to adopting a rare lifestyle with no endocytosis but accumulation of membrane-derived vesicles. Anthraquinone complement indicated that the vesicles in ΔAn could coat the extrinsic anthraquinone-induced granules to prevent contact with the fungal interiors. Detailed chemical investigation on ΔAn led to characterization of a rare oxygen-free ergosterene with unstable nature in air as the major membrane steroid in ΔAn, suggesting hypoxia inner in ΔAn cells, consistent with dramatically low oxygen-consuming rates in ΔAn. A series of physiological and metabolic analyses indicated anthraquinones were involved in exporting ferrous and promoting formation of oxygen-containing metabolites, including ergosterols for endocytosis and iron chelators for iron storage. Moreover, we found that both the anticancer agent mitoxantrone with well-known-cardiotoxicity side effect and the major terpenoid-derived polycyclic aromatics from Danshen for treating cardiovascular disease showed potent ferrous transporting capabilities in human cancer cells. Our findings provide a novel insight into the underlying mechanisms of polycyclic aromatics in nature and pharmacology, and offer a new strategy for developing potential therapeutics and agents for membrane transport, iron homestasis, and anticold.

Comparative transcriptomic insights into the domestication of Pleurotus abieticola for coniferous cultivation

Introduction: Pleurotus abieticola, a promising edible fungus in the Pleurotaceae family, especially its ability to utilize coniferous substrate, holds significant potential for commercial cultivation. However, few reports on the adaptation of P. abieticola to coniferous substrate from the perspective of omics. Methods: This study explores the biological characteristics, domestication process, and nutritional composition of P. abieticola, along with its adaptability to coniferous substrates using transcriptomics. We assessed biological characteristics, optimizing mycelial growth on agar medium with varied carbon and nitrogen sources, temperature, and pH. Additionally, the optimization process extended to fruiting bodies, where impact on the differentiation were evaluated under varying light conditions. Fruiting body nutrient composition was analyzed per the Chinese National Food Safety Standard. Transcriptome sequencing focused on P. abieticola mycelial colonized coniferous and broadleaved substrates. Results and Discussion: The optimal conditions for mycelial growth were identified: dextrin (carbon source), diammonium hydrogen phosphate (nitrogen source), 25°C (temperature), and pH 7.0. White light promoted fruiting body growth and differentiation. Larch substrate exhibited superior yield (190 g) and biological efficiency (38.0%) compared to oak (131 g, 26.2%) and spruce (166 g, 33.2%). P. abieticola showcased high dietary fiber, protein, and total sugar content, low fat, and sufficient microelements. Transcriptome analysis revealed significant key genes involved in lignocellulose degradation, stress-resistant metabolism, and endocytosis metabolism, underscoring their pivotal for coniferous adaptation. This study offers valuable insights for the commercial development and strain breeding of P. abieticola, efficiently leveraging conifer resources. The findings underscore its potential as a valuable source for food, medicinal products, and biotechnological applications.

Peroxin Pex14/17 Is Required for Trap Formation, and Plays Pleiotropic Roles in Mycelial Development, Stress Response, and Secondary Metabolism in Arthrobotrys oligospora

The peroxins encoded by PEX genes involved in peroxisome biogenesis play a crucial role in cellular metabolism and pathogenicity in fungi. Herein, we characterized a filamentous fungus-specific peroxin Pex14/17 in the Arthrobotrys oligospora, a representative species of nematode-trapping fungi. The deletion of AoPEX14/17 resulted in a remarkable reduction in mycelial growth, conidia yield, trap formation, and pathogenicity. Compared with the wild-type strain, the ΔAopex14/17 mutant exhibited more lipid droplet and reactive oxygen species accumulation accompanied with a significant decrease in fatty acid utilization and tolerance to oxidative stress. Transcriptomic analysis indicated that AoPEX14/17 was involved in the regulation of metabolism, genetic information processing, environmental information processing, and cellular processes. In subcellular morphology, the deletion of AoPEX14/17 resulted in a decrease in the number of cell nuclei, autophagosomes, and Woronin bodies. Metabolic profile analysis showed that AoPex14/17 affects the biosynthesis of secondary metabolites. Yeast two-hybrid assay revealed that AoPex14/17 interacted with AoPex14 but not with AoPex13. Taken together, our results suggest that Pex14/17 is the main factor for modulating growth, development, and pathogenicity in A. oligospora. IMPORTANCE Peroxisome biogenesis genes (PEX) play an important role in growth, development, and pathogenicity in pathogenic fungi. However, the roles of PEX genes remain largely unknown in nematode-trapping (NT) fungi. Here, we provide direct evidence that AoPex14/17 regulates mycelial growth, conidiation, trap formation, autophagy, endocytosis, catalase activity, stress response to oxidants, lipid metabolism, and reactive oxygen species production. Transcriptome analysis and metabolic profile suggested that AoPex14/17 is involved in multiple cellular processes and the regulation of secondary metabolism. Therefore, our study extends the functions of PEX genes, which helps to elucidate the mechanism of organelle development and trap formation in NT fungi and lays the foundation for the development of efficient nematode biocontrol agents.