A carnivorous mushroom paralyzes and kills nematodes via a volatile ketone

Author: mycolabadmin
1/18/2023
View Source

Summary

Scientists discovered that oyster mushrooms kill parasitic worms using a toxic gas stored in tiny bulb-shaped structures called toxocysts. The toxin is a common chemical called 3-octanone that ruptures the worms’ cell membranes, causing calcium to flood into cells and leading to rapid paralysis and death. This ‘nerve gas in a lollipop’ strategy could inspire new ways to control parasitic worms in agriculture and medicine.

Background

The oyster mushroom Pleurotus ostreatus is a carnivorous fungus that rapidly paralyzes and kills nematode prey upon contact, but the mechanism and toxin responsible for this predatory behavior were previously unknown. Previous studies identified trans-2-decenedioic acid as a potential nematocidal compound, but this did not fully explain the fast-acting paralysis observed. Understanding the toxin mechanism could reveal novel parasite control strategies.

Objective

To identify the nematocidal toxin produced by P. ostreatus and elucidate the molecular mechanism by which it causes rapid paralysis and cell death in Caenorhabditis elegans nematodes. The study aimed to characterize specialized fungal structures involved in toxin delivery and determine how the toxin disrupts nematode physiology.

Results

Toxocysts, small lollipop-shaped structures on fungal hyphae, were identified as essential for nematode paralysis. 3-Octanone, a volatile ketone, was detected in toxocysts and recapitulated rapid paralysis, calcium influx, and cell necrosis in C. elegans. 3-Octanone disrupted plasma membrane integrity causing extracellular calcium influx into mitochondria, triggering a dosage-dependent calcium wave propagating through nematode tissues and resulting in ATP depletion and necrotic cell death.

Conclusion

P. ostreatus employs a specialized toxocyst structure containing the volatile ketone 3-octanone to rapidly paralyze and kill nematode prey through membrane disruption. The findings demonstrate that natural metabolites can gain additional biological function through morphological evolution, and provide insights into fungal predatory mechanisms that could inform biocontrol strategies against parasitic nematodes.

Published in:Science Advances,
Study Type:Experimental Research Study,
Source: PMID: 36652525, DOI: 10.1126/sciadv.ade4809