Flammulina velutipes, one of the most popular mushroom species in the world, has been recognized as a useful model system to study the biochemical and physiological aspects of the formation and elongation of fruit body. However, few reports have been published on the regulation of fruiting body formation in F. velutipes at the molecular level. In this study, a jacalin-related lectin gene from F. velutipes was characterized. The phylogenetic tree revealed that Fv-JRL1 clustered with other basidiomycete jacalin-like lectins. Moreover, the transcriptional pattern of the Fv-JRL1 gene in different developmental stages of F. velutipes implied that Fv-JRL1 could be important for formation of fruit body. Additionally, RNA interference (RNAi) and overexpression analyses provided powerful evidence that the lectin gene Fv-JRL1 from F. velutipes plays important roles in fruiting body formation.

Volvariella volvacea, usually harvested in its egg stage, is one of the most popular mushrooms in Asia. The rapid transition from the egg stage to elongation stage, during which the stipe stretches to almost full length leads to the opening of the cap and rupture of the universal veil, and is considered to be one of the main factors that negatively impacts the yield and value of V. volvacea. Stipe elongation is a common phenomenon in mushrooms; however, the mechanisms, genes and regulation involved in stipe elongation are still poorly understood. In order to study the genes related to the stipe elongation, we analyzed the transcription of laccase genes in stipe tissue of V. volvacea, as some laccases have been suggested to be involved in stipe elongation in Flammulina velutipes. Based on transcription patterns, the expression of Vvlcc3 was found to be the highest among the 11 laccase genes. Moreover, phylogenetic analysis showed that VvLCC3 has a high degree of identity with other basidiomycete laccases. Therefore, we selected and cloned a laccase gene, named Vvlcc3, a cDNA from V. volvacea, and expressed the cDNA in Pichia pastoris. The presence of the laccase signature L1-L4 on the deduced protein sequence indicates that the gene encodes a laccase. Phylogenetic analysis showed that VvLCC3 clusters with Coprinopsis cinerea laccases. The ability to catalyze ABTS (2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) oxidation proved that the product of the Vvlcc3 gene was a functional laccase. We also found that the expression of the Vvlcc3 gene in V. volvacea increased during button stage to the elongation stage; it reached its peak in the elongation stage, and then decreased in the maturation stage, which was similar to the trend in the expression of Fv-lac3 and Fv-lac5 in F. velutipes stipe tissue. The similar trend in expression level of these laccase genes of F. velutipes suggested that this gene could be involved in stipe elongation in V. volvacea.

Agaricus bisporus, belonging to the genus Agaricus and the family Agaricaceae, is a popular commercially cultivated mushroom with rich nutritional and medical values. Cultivation of A. bisporus requires superior cultivars. Understanding the differences between wild and cultivated accession at the genetic level is crucial for mining loci and genes associated with cultivation-related traits, informing future breeding directions. Additionally, the identification of loci and genes associated with important agronomic traits (e.g., yield and quality) facilitates mushroom molecular breeding. In this study, we conducted sequencing of 200 strains of A. bisporus and analyzed genomic variations. Population structure and genetic relationships were investigated for 200 strains. Selection signs and genes were also obtained after selection sweep analysis. Thirteen candidate genes in the selective elimination regions had significantly different expression patterns at the fruit body stage. Moreover, six genes were identified for the esterase isozyme type through a combination of GWAS and RNA data. This study provides insight into environmental adaptation at the genetic base, providing valuable genetic resources for button mushroom molecular breeding to improve environmental adaptation, quality, or yield.

Spawn aging poses a substantial challenge to the Agaricus bisporus industry. This study focuses on the role of mitochondrial dysfunction in the aging process of A. bisporus spawn. We conducted a comprehensive comparative transcriptome analysis to elucidate the molecular mechanisms underlying A. bisporus spawn aging. A total of 1620 genes with significant expression changes between the normal and aged spawn were identified, including 917 up-regulated genes and 703 down-regulated genes. Our results revealed a notable down-regulation of genes involved in carbohydrate metabolism, mitochondrial energy metabolism, reactive oxygen species (ROS) scavenging, repair mechanisms for oxidative stress-induced damage, fatty acid β-oxidation, and amino acid degradation in aged A. bisporus spawn. Additionally, we observed a decreased expression of genes involved in critical signal transduction pathways associated with mitochondrial function in aged mycelium as well as genes responsible for maintaining mitochondrial stability. The up-regulated genes in aged spawn mainly affect mitochondrial fission and programmed cell death, impacting mitochondrial function. Overall, the present study first provides evidence for the pivotal role of mitochondrial dysfunction in the aging process of A. bisporus spawn and contributes to the development of targeted strategies to enhance mitochondrial function, mitigate spawn aging, and improve the yield and quality of A. bisporus cultivation.

Molecular markers and genetic maps are useful tools in genetic studies. Novel molecular markers and their applications have been developed in recent years. With the recent advancements in sequencing technology, the genomic sequences of an increasingly great number of fungi have become available. A novel type of molecular marker was developed to construct the first reported linkage map of the edible and economically important basidiomycete Volvariella volvacea by using 104 structural variation (SV) markers that are based on the genomic sequences. Because of the special and simple life cycle in basidiomycete, SV markers can be effectively developed by genomic comparison and tested in single spore isolates (SSIs). This stable, convenient and rapidly developed marker may assist in the construction of genetic maps and facilitate genomic research for other species of fungi.

Agaricus bisporus is popular worldwide because of its high nutritional value and low cost. Low-temperature storage is a common storage method used for the production and sales of A. bisporus cultivation spawn, but few studies have focused on the physiological and biochemical mechanisms associated with low-temperature storage of A. bisporus cultivation spawn. In this study, we examined A. bisporus spawn samples stored for different refrigeration periods (0, 20, 40, 60, 80, and 100 days), measured changes in the activities of four key extracellular enzymes and performed transcriptomic and metabolomic analyses. The results of the enzymatic assays revealed that the activities of carboxymethyl cellulase (CMCase), amylase, and acid protease initially decreased before increasing, whereas laccase activity showed the opposite trend. This pattern may represent an energy supply mechanism adopted by A. bisporus to cope with low temperatures, where extracellular enzymes indirectly influence survival by mediating substrate decomposition. Further correlation analysis on the basis of CMCase activity changes revealed 148 carboxymethyl cellulase-correlated metabolites (CCMs) and 514 carboxymethyl cellulase-correlated genes (CCGs) (p ≤ 0.05), and significance was determined at FDR < 0.05 with a fold change > 1.5. Among these, 56.08% of the CCMs and 63.04% of the CCGs presented positive correlations with CMCase activity, whereas 43.92% and 36.96% presented negative correlations, respectively. Integrated multiomics analysis revealed significant variations in metabolic flux and gene expression across different storage durations. Two CCMs (ketoleucine and 3-methyl-2-oxovaleric acid) gradually decreased in expression, whereas two CCGs (AbbBCAT and AbbAACS) increased in expression. This study provides novel insights into the molecular adaptation of A. bisporus spawn to refrigeration, highlighting the importance of branched-chain amino acid metabolism in the cold stress response and storage stability.