Pleurotus ostreatus is a widely cultivated edible fungus in China. Green mold disease of P. ostreatus which can seriously affect yield is a common disease during cultivation. It occurs mostly after P. ostreatus mycelia have been subjected to high temperatures. However, little information is available on the relationship between high temperature and green mold disease. The aim of this study is to prove that extracellular metabolites of P. ostreatus affected by high temperature can promote the growth of Trichoderma asperellum. After P. ostreatus mycelia was subjected to high temperature, the extracellular fluid of P. ostreatus showed a higher promoting effect on mycelial growth and conidial germination of T. asperellum. The thiobarbituric acid reactive substance (TBARS) content reached the maximum after 48 h at 36°C. A comprehensive metabolite profiling strategy involving gas chromatography-mass spectrometry (GC/MS) combined with liquid chromatography-mass spectrometry (LC/MS) was used to analyze the changes of extracellular metabolites in response to high temperature. A total of 141 differential metabolites were identified, including 84.4% up-regulated and 15.6% down-regulated. Exogenous metabolites whose concentrations were increased after high temperature were randomly selected, and nearly all of them were able to promote the mycelial growth and conidial germination of T. asperellum. The combination of all selected exogenous metabolites also has the promotion effects on the mycelial growth and conidial germination of T. asperellum in a given concentration range in vitro. Overall, these results provide a first view that high temperature affects the extracellular metabolites of P. ostreatus, and the extensive change in metabolites promotes T. asperellum growth.

Trichoderma asperellum is one of the species which can be isolated from contaminated Pleurotus ostreatus cultivation substrate with green mold disease. This study focused on the relationship between high temperature and infectivity of T. asperellum to P. ostreatus. Antagonism experiments between T. asperellum and P. ostreatus mycelia revealed that high temperature-treated P. ostreatus mycelia were more easily infected by T. asperellum and covered by conidia. Microscopic observation also showed that P. ostreatus mycelia treated with high temperature could adsorb more T. asperellum conidia. Furthermore, conidia obtained from T. asperellum mycelia grown at 36°C featured higher germination rate compared with that incubated at 28°C. High temperature-treated T. asperellum mycelia can produce conidia in shorter periods, and T. asperellum mycelia were less sensitive to high temperature than P. ostreatus. Deactivated P. ostreatus mycelia can induce T. asperellum cell wall-degrading enzymes (CWDEs) and P. ostreatus mycelia subjected to high temperature showed induced CWDEs more effective than those incubated at 28°C. Moreover, T. asperellum showed higher CWDEs activity at high temperature. In dual cultures, hydrogen peroxide (H₂O₂) increased after 36°C, and high concentration of H₂O₂ could significantly inhibit the growth of P. ostreatus mycelia. In summary, our findings indicated for the first time that high temperature can induce a series of mechanisms to enhance infection abilities of T. asperellum to P. ostreatus mycelia and to cause Pleurotus green mold disease.

Auricularia heimuer is a traditional edible and medicinal mushroom, which is widely used in biochemical research and is regarded as a good dietary supplement. The color of the ear-like fruiting body is an important indicator of its commercial quality. However, the mechanism by which light intensity influences the melanin synthesis of A. heimuer remains unclear. Here, we show that fruiting body color is significantly affected by light intensity. Transcriptional profiles of the fruiting bodies of A. heimuer grown in different light intensities were further analyzed. More differentially expressed genes (DEGs) were identified with a greater light intensity difference. A total of 1388 DEGs were identified from six comparisons, including 503 up-regulated genes and 885 down-regulated genes. The up-regulated genes were mainly associated with light sensing via photoreceptors, signal transduction via the mitogen-activated protein kinase (MAPK) signaling pathway, and melanin synthesis via the tyrosine metabolic pathway. Therefore, the genes involved in these processes may participate in regulating melanin synthesis under high light intensity. This insight into the transcriptional regulation of A. heimuer to light intensity should help to further comprehensively elucidate the underlying mechanism of light-induced melanin synthesis.

The genes associated with fruiting body formation of Sparasis latifolia are valuable for improving mushroom breeding. To investigate this process, 4.8 × 10⁸ RNA-Seq reads were acquired from three stages: hyphal knot (SM), primordium (SP), and primordium differentiation (SPD). The de novo assembly generated a total of 48,549 unigenes, of which 71.53% (34,728) unigenes could be annotated by at least one of the KEGG (Kyoto Encyclopedia of Genes and Genomes), GO (Gene Ontology), and KOG (Eukaryotic Orthologous Group) databases. KEGG and KOG analyses respectively mapped 32,765 unigenes to 202 pathways and 19,408 unigenes to 25 categories. KEGG pathway enrichment analysis of DEGs (differentially expressed genes) indicated primordium initiation was significantly related to 66 pathways, such as “Ribosome”, “metabolism of xenobiotics by cytochrome P450”, and “glutathione metabolism” (among others). The MAPK and mTOR signal transduction pathways underwent significant adjustments during the SM to SP transition. Further, our research revealed the PI3K-Akt signaling pathway related to cell proliferation could play crucial functions during the development of SP and SPD. These findings provide crucial candidate genes and pathways related to primordium differentiation and development in S. latifolia, and advances our knowledge about mushroom morphogenesis.