Construction and application of a gene silencing system using a dual promoter silencing vector in Hypsizygus marmoreus

Gene Silencing via RNA Interference in Cryptococcus

RNA interference (RNAi) is a molecular biology technique for silencing specific eukaryotic genes without altering the DNA sequence in the genome. The silencing effect occurs because of decreased levels of mRNA that then result in decreased protein levels for the gene. The specificity of the silencing is dependent upon the presence of sequence-specific double-stranded RNA (dsRNA) that activates the cellular RNAi machinery. This chapter describes the process of silencing a specific target gene in Cryptococcus using a dual promoter vector. The plasmid, pIBB103, was designed with two convergent GAL7 promoters flanking a ura5 fragment that acts as a reporter for efficient RNAi. The target gene fragment is inserted between the promoters to be transcribed from both directions leading to the production of dsRNA in cells that activate the RNAi pathway.

Comparative transcriptome analysis on candidate genes associated with fruiting body growth and development in Lyophyllum decastes

Lyophyllum decastes is a mushroom that is highly regarded for its culinary and medicinal properties. Its delectable taste and texture make it a popular choice for consumption. To gain a deeper understanding of the molecular mechanisms involved in the development of the fruiting body of L. decastes, we used RNA sequencing to conduct a comparative transcriptome analysis. The analysis encompassed various developmental stages, including the vegetative mycelium, primordial initiation, young fruiting body, medium-size fruiting body, and mature fruiting body stages. A range of 40.1 to 60.6 million clean reads were obtained, and de novo assembly generated 15,451 unigenes with an average length of 1,462.68 bp. Functional annotation of transcriptomes matched 76.84% of the unigenes to known proteins available in at least one database. The gene expression analysis revealed a significant number of differentially expressed genes (DEGs) between each stage. These genes were annotated and subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. Highly differentially expressed unigenes were also identified, including those that encode extracellular enzymes, transcription factors, and signaling pathways. The accuracy of the RNA-Seq and DEG analyses was validated using quantitative PCR. Enzyme activity analysis experiments demonstrated that the extracellular enzymes exhibited significant differences across different developmental stages. This study provides valuable insights into the molecular mechanisms that underlie the development of the fruiting body in L. decastes.

Research Progress on Edible Fungi Genetic System

In order to obtain strains with targeted changes in genetic characteristics, molecular biology and genetic engineering techniques are used to integrate target gene fragments into the vector and transform them into recipient cells. Due to the different target genes and functional elements on the transformation plasmids, gene silencing, gene knockout, and gene overexpression can be carried out, which provides a new way to study the gene function of edible fungi. At present, the cloning vectors used in the transformation of edible fungi are modified by bacterial plasmids, among which pCAMBIA-1300 plasmid and pAN7 plasmid are the two most commonly used basic vectors. On this basis, some basic elements such as promoters, selective marker genes, and reporter genes were added to construct silencing vectors, knockout vectors, and overexpression vectors. At the same time, different expression vector systems are needed for different transformation methods. In this chapter, the main elements of the genetic system (promoters, screening markers), the current main genetic transformation methods (Agrobacterium-mediated transformation, liposome transformation, electroporation method), and the specific application of transformation were systematically summarized, which provides a reference for the study of the genetic system of edible fungi.

Hydrogen-rich water increases postharvest quality by enhancing antioxidant capacity in Hypsizygus marmoreus

In the present study, we aimed to assess the effect of hydrogen-rich water (HRW) on the physicochemical characteristics and antioxidant capacity of Hypsizygus marmoreus during 12 days of postharvest storage at 4 °C. Different concentrations of HRW (25, 50 and 100%) were tested, and our data showed that 25% HRW treatment had the most significant effect on preservation of nutrients in H. marmoreus compared with the control group. In addition, 25% HRW treatment significantly reduced the relative electrolyte leakage rate and malonaldehyde (MDA) content (P < 0.05) and increased anti-superoxide-radical (O₂^-) activity compared with the control group. The activities of antioxidants, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) were activated by 25% HRW treatment, and the expression levels of these genes were also induced. These results suggested that HRW treatment could delay rot incidence in mushrooms during storage by regulating antioxidant defense ability. This study supplies a new and simple method to maintain the quality and extend the shelf life of mushrooms.

Hydrogen-rich water alleviates the toxicities of different stresses to mycelial growth in Hypsizygus marmoreus

In plants, hydrogen gas (H₂) enhances tolerance to several abiotic stresses, including salinity and heavy metals. However, the effect of H₂ on fungal growth under different stresses remains largely unclear. In this study, hydrogen-rich water (HRW) was employed to characterize physiological roles and molecular mechanisms of H₂ in the alleviation of three different stresses in basidiomycete Hypsizygus marmoreus. Our results showed that HRW treatment, of which the H₂ concentration was 0.8 mM, significantly reduced the toxicities of CdCl₂, NaCl and H₂O₂, leading to significantly improved mycelial growth and biomass. These beneficial effects could be attributed to a significantly decreased formation of malondialdehyde (MDA). Besides, HRW treatment significantly increased the activities of antioxidants (SOD, CAT and GR) as well as the gene expressions of these antioxidants (SOD, CAT, and GR) at the mRNA level. In vivo detection of reactive oxygen species (ROS), including H₂O₂ and O₂⁻, as well as lipid peroxidation provided further evidence that HRW could significantly improve tolerances of CdCl₂, NaCl and H₂O₂. Furthermore, pyruvate kinase was activated in the mycelia treated with HRW, along with its induced gene expression, suggesting that HRW treatment enhanced the glucose metabolism. Taken together, our findings suggested that the usage of HRW could be an effective approach for contaminant detoxification in H. marmoreus, which was similar with the effects of HRW in plants, and such effects could be also beneficial in entire agricultural system.