In the study by Nakazawa et al. (2023b), the authors claim that the sextuple deletion of vp2, vp3, mnp2, mnp3, mnp6, and lac2 in P. ostreatus results in a near-complete loss of lignin-degrading ability on beech wood sawdust (BWS), presenting it as direct evidence of the essentiality of these lignin-modifying enzymes (LMEs). However, given the functional redundancy often observed among peroxidases and laccases in fungi, how can we be sure that this phenotype is not due to unintended off-target effects or global physiological impairments from multiple gene deletions rather than the absence of these specific enzymes alone? Was there any transcriptomic or proteomic verification to confirm the specificity of the deletions and the lack of compensatory enzyme expression?
Upon reading this published review, a major concern regarding scholarly rigor and reproducibility is the repeated citation of data and conclusions from sources listed as “to be published elsewhere” (e.g., Schiphof et al.; Kawauchi et al.; Koshi et al.).
In a final, peer-reviewed publication, this citation practice is highly problematic:
Violates Academic Norms: Published literature must allow for the verification of claims. Citing completely inaccessible work undermines this fundamental principle. These are not “personal communications”; they are presented as formal references but point to a void.
Compromises the Review’s Foundation: Key arguments, about cell wall composition (Kawauchi et al.), chitin synthase phylogeny (Schiphof et al.), and a novel genome editing method (Koshi et al.), are built upon foundations the reader cannot inspect. This turns these sections into unsupported assertions rather than evidence-based summaries.
Hinders Scientific Discourse: Other researchers cannot evaluate, critique, or build upon these findings, which stifles the very progress the review aims to inspire.
For a review article that successfully argues for P. ostreatus as a model system based on robust genetic tools, it is ironic that several of its own critical points rely on “tools” (data, methods) that are kept private. This pervasive issue significantly weakens its authority and utility as a reference.