Color is a crucial feature to consider when breeding and improving strains of Auricularia cornea. To uncover the mechanism of white strain formation in A. cornea, this study selected parental strains that were homozygous for the color trait and analyzed the genetic laws of A. cornea color through genetic population construction, such as test-cross, back-cross, and self-cross populations, and the statistical analysis of color trait segregation. Moreover, the study developed SSR molecular markers to construct a genetic linkage map, perform the fine mapping the color-controlling genetic locus, and verify candidate genes using yeast two-hybrid, transcriptome analysis, and different light treatments. The results of the study indicated that the color trait of A. cornea is controlled by two pairs of alleles. When both pairs of loci are dominant, the fruiting body is purple, while when both pairs of loci are recessive or one pair of loci is recessive, the fruiting body is white. Based on the linkage map, the study finely mapped the color locus within Contig9_29,619bp-53,463bp in the A. cornea genome and successfully predicted the color-controlling locus gene A18078 (AcveA), which belongs to the Velvet factor family protein and has a conserved structure domain of the VeA protein. It can form a dimer with the VelB protein to inhibit pigment synthesis in filamentous fungi. Lastly, the study validated the interaction between AcVeA and VelB (AcVelB) in A. cornea at the gene, protein, and phenotype levels, revealing the mechanism of inhibition of pigment synthesis in A. cornea. Under dark conditions, dimerization occurs, allowing it to enter the nucleus and inhibit pigment synthesis, leading to a lighter fruiting body color. However, under light conditions, the dimer content is low and cannot enter the nucleus to inhibit pigment synthesis. In summary, this study clarified the mechanism of white strain formation in A. cornea, which could aid in improving white strains of A. cornea and studying the genetic basis of color in other fungi.

Auricularia heimuer is a wood-rotting edible mushroom, and with the continuous development of the industry, the research on its grass-rotting cultivation is becoming more and more important. In this study, A. heimuer was cultivated using herbaceous substrate (reed) completely replacing the traditional woody substrate (oak), and the correlation between the relative expression of cellulase gene, cellulase activity, cellulose degradation and yield of different strains of A. heimuer were studied by combining qRT-PCR technology at different growth stages. The results showed that the cellulose degradation were positively correlated with the yield of reed and sawdust substrate at two growth stages, and were positively correlated with three cellulase activities. The relative expression of four cellulase genes were positively correlated with enzyme activity. There were inter-strain differences in the expression of the enzyme genes, which were basically consistent with the trend of the enzyme activity of the strains; g5372 and g7270 were more actively expressed in the mycelium period, while g9664 and g10234 were more actively expressed in the fruiting period. The results of SEM showed that the mycelium of A15 and A125 were different in their ability to degrade and utilize lignocellulose in reed substrate. The parental hybridization test further verified that qRT-PCR could be used as a rapid method to evaluate the cellulose degradation ability of A. heimuer strains. Seven strains (A12, A15, A184, A224, Z6, Z12, and Z18) with high cellulose degradation ability were screened. This study provides a reference for further understanding the role of A. heimuer cellulase genes in the degradation and metabolism of cellulose and for breeding new varieties more suitable for herbaceous substrate cultivation.

Stropharia rugosoannulata is a mushroom that is rich in nutrients and has a pleasant flavor. Its cultivation area is expanding rapidly due to its simplicity and diversity. However, the developmental mechanism of the fruiting body, which constitutes the edible portion of S. rugosoannulata, remains to be elucidated. To address this knowledge gap, we conducted a comprehensive study. Our approach entailed the observation of sections through the fruiting body of S. rugosoannulata and the sequencing of the transcriptomes of various fruiting body tissues. The results demonstrated significant variations in the structure of the pileipellis, pileus, gill, veil, stipe, and trama of S. rugosoannulata. The predominant metabolic pathways included the amino acid metabolism of the pileus, sugar metabolism of the stipe, tryptophan metabolism, and wax production of the pileipellis, the DNA pathway of the gill, amino sugar metabolism of the veil, and the nitrogen metabolism of the trama. The promoter cis-element analysis revealed the roles of light response, methyl jasmonate, oxygen, and temperature on the differentiation of the veil, trama, and pileipellis, respectively. In summary, the present findings offer a molecular mechanism for the development of the fruiting body and provide directions for the enhancement of cultivation techniques of S. rugosoannulata.

Auricularia heimuer is a widely cultivated jelly mushroom. The fruiting bodies are categorized into cluster and chrysanthemum types. With changing consumer demands and the need to reduce bio-waste, the demand for clustered fruiting bodies is increasing. Therefore, gene mining for fruiting body types is a matter of urgency. We determined that the A. heimuer locus for fruiting body type was located at one end of the genetic linkage map. The locus was localized between the markers D23860 and D389 by increasing the density of the genetic linkage map. BlastN alignment showed that the marker SCL-18 was also located between D23860 and D389, and a total of 25 coding genes were annotated within this interval. Through parental transcriptome analysis and qRT-PCR verification, the locus g7219 was identified as the gene controlling the fruiting body type. A single-nucleotide substitution in the TATA box of g7219 was detected between the parents. By PCR amplification of the promoter region of g7219, the TATA-box sequences of the cluster- and chrysanthemum-type strains were found to be CATAAAA and TATAAAA, respectively. This study provides a foundation for the breeding of fruiting body types and strain improvement of A. heimuer.

Zinc and lysine have been identified as beneficial components of Flammulina filiformis. This work investigated the effects of different concentrations of Zn²⁺ on mycelia growth, zinc content, amino acid composition of F. filiformis. To explore the mechanism of action of zinc on lysine synthesis in F. filiformis mycelia, this work studied at the molecular level. The cultivated strain FV8 and the wild strain FV18 were utilized as the research subjects. Various concentrations of Zn²⁺ (0, 10, 20, 30 mg/L) were added in the PDA medium for the experiments. The results indicated that the maximum lysine content was reached in the 20 mg/L treatment. A positive correlation was identified between Zn²⁺ and the lysine content in F. filiformis mycelia, suggesting a regulatory role for Zn²⁺ in the expression of lysine synthesis pathway genes. Zn²⁺ has been observed to promote the upregulated expression of HDH and HCD, while concomitantly exerting a negative effect on the expression of AAT in key enzyme genes of the lysine synthesis pathway. The F. filiformis mycelia exhibited a notable enrichment capacity for zinc, with the highest zinc content observed in the 30 mg/L treatment. The zinc-enriched growth performance of wild strain FV18 was found to be superior to that of cultivated strain FV8, which is considered a suitable breeding material. This study provides a foundation for further exploration of the lysine synthesis pathway in F. filiformis mycelia, and selection of functional varieties of F. filiformis.

Auricularia heimuer is the second most widely cultivated edible fungus in China, with significant food and medicinal value, and is highly popular throughout Asia and globally. However, the differentiation of A. heimuer is simple, as its morphology is characterized by a small “black disc”, making it difficult to distinguish among germplasms with highly similar agronomic traits, thus posing challenges for germplasm identification. To address this issue, this study conducted whole-genome resequencing analysis on 150 A. heimuer germplasms. Through filtering 9,589,911 SNPs obtained from 280 G resequencing data, a total of 1,202,947 high-quality SNP sites were identified. Based on these high-quality SNPs, population structure analysis, principal component analysis (PCA), and phylogenetic tree analysis revealed that the 150 A. heimuer germplasms could be divided into five groups, with wild strains from the same geographical origin exhibiting significant geographical clustering patterns. This finding underscores the relationship between the genetic diversity of wild A. heimuer and its geographical distribution in China. A further selection of 71 SNP sites was made, and 61 KASP markers were successfully developed using kompetitive allele-specific PCR (KASP) technology, with 54 of them demonstrating good polymorphism. The average values for the polymorphism information content (PIC), minor allele frequency (MAF), gene diversity, and heterozygosity of these core KASP markers were 0.34, 0.35, 0.34, and 0.43, respectively. Based on the 54 core KASP markers, a DNA fingerprinting map of the 150 A. heimuer germplasms was constructed in this study. The findings provide important molecular marker resources and theoretical support for the identification of A. heimuer germplasm, molecular marker-assisted breeding, and the selection of superior varieties.