The Cas9-gRNA ribonucleoprotein complex-mediated editing of pyrG in Ganoderma lucidum and unexpected insertion of contaminated DNA fragments

Utilization of CRISPR-Cas genome editing technology in filamentous fungi: function and advancement potentiality

Filamentous fungi play a crucial role in environmental pollution control, protein secretion, and the production of active secondary metabolites. The evolution of gene editing technology has significantly improved the study of filamentous fungi, which in the past was laborious and time-consuming. But recently, CRISPR-Cas systems, which utilize small guide RNA (sgRNA) to mediate clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas), have demonstrated considerable promise in research and application for filamentous fungi. The principle, function, and classification of CRISPR-Cas, along with its application strategies and research progress in filamentous fungi, will all be covered in the review. Additionally, we will go over general matters to take into account when editing a genome with the CRISPR-Cas system, including the creation of vectors, different transformation methodologies, multiple editing approaches, CRISPR-mediated transcriptional activation (CRISPRa) or interference (CRISPRi), base editors (BEs), and Prime editors (PEs).

Pleurotus ostreatus as a model mushroom in genetics, cell biology, and material sciences

Pleurotus ostreatus, also known as the oyster mushroom, is a popular edible mushroom cultivated worldwide. This review aims to survey recent progress in the molecular genetics of this fungus and demonstrate its potential as a model mushroom for future research. The development of modern molecular genetic techniques and genome sequencing technologies has resulted in breakthroughs in mushroom science. With efficient transformation protocols and multiple selection markers, a powerful toolbox, including techniques such as gene knockout and genome editing, has been developed, and numerous new findings are accumulating in P. ostreatus. These include molecular mechanisms of wood component degradation, sexual development, protein secretion systems, and cell wall structure. Furthermore, these techniques enable the identification of new horizons in enzymology, biochemistry, cell biology, and material science through protein engineering, fluorescence microscopy, and molecular breeding. KEY POINTS: • Various genetic techniques are available in Pleurotus ostreatus. • P. ostreatus can be used as an alternative model mushroom in genetic analyses. • New frontiers in mushroom science are being developed using the fungus.

An Efficient CRISPR/Cas9 Genome Editing System for a Ganoderma lucidum Cultivated Strain by Ribonucleoprotein Method

The CRISPR/Cas9 system has become a popular approach to genome editing. Compared with the plasmid-dependent CRISPR system, the ribonucleoprotein (RNP) complex formed by the in vitro assembly of Cas9 and single-guide RNA (sgRNA) has many advantages. However, only a few examples have been reported and the editing efficiency has been relatively low. In this study, we developed and optimized an RNP-mediated CRISPR/Cas9 genome editing system for the monokaryotic strain L1 from the Ganoderma lucidum cultivar 'Hunong No. 1'. On selective media containing 5-fluoroorotic acid (5-FOA), the targeting efficiency of the genomic editing reached 100%. The editing efficiency of the orotidine 5'-monophosphate decarboxylase gene (ura3) was greater than 35 mutants/107 protoplasts, surpassing the previously reported G. lucidum CRISPR systems. Through insertion or substitution, 35 mutants introduced new sequences of 10-569 bp near the cleavage site of ura3 in the L1 genome, and the introduced sequences of 22 mutants (62.9%) were derived from the L1 genome itself. Among the 90 mutants, 85 mutants (94.4%) repaired DNA double-strand breaks (DSBs) through non-homologous end joining (NHEJ), and five mutants (5.6%) through microhomology-mediated end joining (MMEJ). This study revealed the repair characteristics of DSBs induced by RNA-programmed nuclease Cas9. Moreover, the G. lucidum genes cyp512a3 and cyp5359n1 have been edited using this system. This study is of significant importance for the targeted breeding and synthetic metabolic regulation of G. lucidum.