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The Achilles Heel of Nematodes

Research group from the Institute of Molecular Biology, Academia Sinica, use the nematode as a model to investigate the mechanism by which oyster mushrooms paralyze and kill nematodes.

Using Caenorhabditis elegans (C. elegans) as a nematode model, Dr Hsueh Yen-Ping’s research group investigated how mushrooms paralyze and kill nematodes. In a study published in PNAS, the team demonstrated that the contact of fungal hyphae on oyster mushrooms triggers a massive calcium ion influx, resulting in rapid cell necrosis in the neuromuscular system of C. elegans through the nematode’s sensory cilia.

This revealed a newly discovered mechanism of rapid nematode killing by fungi that is distinct from those used in common anthelmintic drugs. Thus, representing a potential new route for targeting parasitic nematode infections in animals and agriculture. This novel mechanism establishes a new paradigm for studying cell death in C. elegans.

Dr Hsueh’s laboratory also studied the interactions between nematodes and nematode-trapping fungi (NTF). These are predatory fungi which target nematodes when food sources are limited. In the recent published paper, Dr Hsueh and his research team investigated the natural population of nematodes and NTF in Taiwan.

NTF were found to be ubiquitous in soils, present in more than two out of three soil samples collected in Taiwan, and in particular Arthrobotrys species were sympatric with various nematode species and behaved as generalist predators.

The ability to sense prey varies between different wilde isolates of A. oligospora, the most common NTF found in nature. Those strains with highly sensitive to nematodes also developed traps faster. This polymorphic feature correlated with competency in prey killing and the phylogeny of A. oligospora natural strains. The genome was assembled and annotated for a robust wild isolate that outperformed the current NTF model stain in growth fitness and predatory behaviour.

The team also established that G protein signalling is required for predation in A. oligospora. In summary, this work revealed the natural history and the natural diversity of the predatory behaviour of the nematode-trapping fungi.

Genetic and genomic tools were further developed for a robust wild isolate of A. oligospora, enabling this strain to serve as a new model to study the molecular mechanisms of interactions between predatory fungi and nematodes. This study will help the development of using NTF as biocontrol tools to manage the parasitic nematode infections in agriculture. [APBN]