Auricularia heimuer (A. heimuer F. Wu, B. K. Cui, Y. C. Dai), a well-known gelatinous fungus used for both food and medicine, is a major edible fungus with a more than 1000-year history of cultivation in China. The nutrients of A. heimuer are abundant, including polysaccharides, melanin, mineral elements, etc. The A. heimuer polysaccharides exhibit antioxidant, immunomodulatory, and anticancer properties. A. heimuer is a completely different species grown in China, unlike Auricularia auricula-judae (Bull.) Quel, which was used to characterize it. The cultivated strain varies based on the local climatic factors and cultivation practices. Hardwood chips are the primary material utilized in the cultivation of substitute materials, which is the principal cultivation technique. However, in actual production, straw is frequently replaced for some wood chips to address the issue of a lack of wood. There are three different types of growing techniques: open-air ground cultivation, arch cultivation, and shed-type hanging substitute cultivation of these three, the quality of A. heimuer grown in a shed is superior to that grown in an open-air environment. The A. heimuer genome sequencing project started later than expected, and the entire genome sequencing was not finished until 2019. A. heimuer’s molecular biology studies have mostly concentrated on analyzing genetic diversity and identifying cultivars using molecular markers including RAPD, ISSR, and ITS. There have only been a small number of studies on the function of A. heimuer genes, which have only focused on the preliminary cloning and expression study of a few genes, including the laccase gene and the triterpene compound production gene, among others. However, there is still a lack of comprehensive information concerning A. heimuer, necessitating a synopsis. To our knowledge, this is the first published review of A. heimuer, and it summarizes the most recent studies on its molecular biology and cultivation. This review can serve as a guide for future research on the fungus.

High-temperature stress is a key factor that reduces the yields of edible fungi. Auricularia heimuer (A. heimuer) is a nutrient-rich edible fungus that is widely cultivated in China. In this study, we analyzed the physiological, transcriptomic, and metabolomic results of A. heimuer (variety “Hei29”) under high-temperature stress. Our findings revealed that high temperatures (30 °C and 35 °C) significantly reduced hyphal growth, increased malondialdehyde content and antioxidant enzyme activity, and enhanced the accumulation of secondary metabolites, such as phenolic compounds and flavonoids. A total of 15 candidate genes potentially responsive to high-temperature stress were identified through transcriptomic analysis, including those involved in regulating antioxidant defense, heat shock response, sugar metabolism, amino acid metabolism, and accumulating secondary metabolites. Metabolomic analysis identified three candidate metabolites potentially responsive to high-temperature stress, including kinetin, flavonoids, and caffeic acid, as well as several metabolic pathways, including nucleotide metabolism, ABC transporters, and cofactor biosynthesis. These mechanisms help mitigate oxidative damage to cellular structures and energy deficits caused by elevated temperatures, enabling the fungus to maintain cellular stability, metabolic function, and growth under heat stress. This study is the first to explore the molecular mechanism of A. heimuer in response to high-temperature stress. The results provide valuable insights into the molecular mechanisms of heat stress tolerance in A. heimuer, highlighting potential targets for developing heat-tolerant strains for industrial application.

Auricularia heimuer is a valuable traditional Chinese fungus used as food and medicine. Hei29 is a strain derived from wild A. heimuer through systematic domestication and selection. It has been the primary A. heimuer variety in Northeast China for 30 years and offers the advantages of high yield, good commercial property, and stable traits. This study used protoplast nucleation on Hei29 to produce two amiable and paired monokaryons, Hei29-D1 and Hei29-D2. The genome of Hei29 was sequenced utilizing the Illumina PE150 and PacBio Sequel sequencing platforms. Hei29-D1 and Hei29-D2 had genomic sizes of 47.54 Mb and 47.49 Mb, GC contents of 56.95% and 56.99%, and an N50 of 2.37 Mb and 4.28 Mb, respectively. Hei29’s genome possessed two phytoene synthase (PSY) protein genes, one of which—PSY encoded by g894—has a transmembrane domain. The phylogenetic tree showed that Hei29 shared the closest evolutionary relationship with Auricularia subglabra TFB-10046 SS5. Collinearity analysis showed that the correlation between the two monokaryons was as high as 90.81%. Cluster analysis revealed that Hei29 contains 12,362 core genes, 223 unique genes in Hei29-D1, and 228 unique genes in Hei29-D2. This study is the first to sequence two related and paired monokaryons from A. heimuer, which is critical for fully understanding the genetic composition and information of the characteristic strain of A. heimuer in Northeast China. It establishes the data and theoretical foundation for gene mining, usage, and molecular breeding. It further promotes the genetic breeding and active substance utilization of A. heimuer.