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Orthrus: a Pumilio-family gene involved in fruiting body and dark stipe development in Coprinopsis cinerea

Summary

Scientists studied a gene called ort2 in mushrooms that controls how fruiting bodies develop, especially the long structures called dark stipes that form in darkness. They found that when this gene is active, mushrooms make more of these elongated forms, while disabling it prevents dark stipe formation. This discovery could help improve mushroom cultivation for species where these elongated forms are commercially valuable.

Background

Fruiting bodies of mushroom-forming fungi are complex multicellular structures whose formation is regulated by developmental programs responsive to environmental changes. However, the genetic architecture controlling fruiting body development, particularly dark stipe formation, remains poorly understood. Pumilio family RNA-binding proteins have shown dynamic expression during fruiting body formation but have not been experimentally studied for developmental roles in fungi.

Objective

To characterize a novel Pumilio family gene (ort2) and investigate its role in fruiting body development and dark stipe formation in Coprinopsis cinerea. The study aimed to identify conserved subfamilies within the Pumilio protein family and determine the functional significance of ort2 through reverse genetics and phenotypic analysis.

Results

Five conserved Pumilio subfamilies were identified across Agaricomycetes. Disruption of ort2 resulted in deficient dark stipe formation and delayed fruiting body development, while overexpression significantly increased dark stipe production and improved fruiting body maturation frequency. Rare branching phenotypes observed in overexpression mutants led to the gene’s naming after Orthrus, the two-headed mythological dog.

Conclusion

Ort2 is the first RNA-binding protein documented to influence fruiting body development in fungi, with particular significance for dark stipe formation. The gene appears to function independently of known light-regulated pathways. These findings provide a novel entry point for understanding post-transcriptional regulation of fruiting body development and may have practical applications in mushroom cultivation.
  • Published in:Frontiers in Fungal Biology,
  • Study Type:Experimental Study,
  • Source: PMC12344735, PMID: 40809782, doi: 10.3389/ffunb.2025.1633301
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