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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 a common lab mushroom species to understand how mushrooms develop their fruiting bodies. They found that this gene is particularly important for developing dark stipes – elongated structures that mushrooms grow in darkness to push themselves toward light. By turning this gene off or increasing its activity, researchers could control how many dark stipes formed, suggesting this gene could have practical applications in mushroom farming.

Background

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

Objective

To characterize a novel Pumilio family gene (ort2) and investigate its role in fruiting body development, particularly in dark stipe formation, in the model fungal species Coprinopsis cinerea. The study aimed to determine the gene’s function through phylogenetic analysis and reverse genetics experiments.

Results

Pumilio proteins form five conserved subfamilies in fungi. The ort2 deletion mutants showed deficient dark stipe formation under darkness, while overexpression strains produced significantly more dark stipes (approximately 7.5-fold increase). Overexpression also resulted in rare branching fruiting body phenotypes and improved fruiting body maturation rates. No evidence for mitochondrial biogenesis function was found, distinguishing ort2 from its yeast orthologs.

Conclusion

Ort2 is the first RNA-binding protein documented to influence fruiting body development in mushrooms, with particularly strong effects on dark stipe formation. The gene acts independently of light-regulated pathways and may contribute to nodulus functioning. These findings could have applications in mushroom cultivation and suggest that further characterization of RNA regulatory networks may illuminate aspects of complex multicellularity in fungi.
  • Published in:Frontiers in Fungal Biology,
  • Study Type:Experimental Study,
  • Source: PMID: 40809782
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