Venom beyond animals: The toxic arsenal of fungi, plants, and microbes

Newly published research suggests that toxins aren’t reserved for creatures like snakes, spiders, or scorpions, which we’ve traditionally labeled as venomous. A surprising cast of organisms also use comparable tactics.

Growing evidence indicates that many plants, fungi, and microorganisms rely on venom-like methods to protect themselves from threats and outmaneuver other organisms. The research challenges assumptions we’ve held about which living things can deliver a harmful punch and opens new doors for scientific inquiry.

Venomous animals have long fascinated biologists that were seeking to understand their deadly secretions and the traits associated with their use, but have also contributed numerous life-saving therapeutics, said William K. Hayes, professor of biology at Loma Linda University School of Medicine. 

This perspective casts a wider net over organisms that employ toxic secretions, raising hopes that an even broader range of life forms could offer untapped chemical treasures for medicine and research.

Venom goes beyond animals

Researchers have begun to expand the basic definition of venom beyond what is produced by snakes or spiders, since a strictly animal-based perspective overlooks key examples in other branches of life.

A toxin introduced into the internal tissues of a target through a specialized structure could also describe the stinging hairs on some plants, the penetration mechanisms used by certain fungi, and even the injection systems of a few bacteria.

One example includes certain nettle species that can puncture skin upon contact, while other flora form alliances with stinging ants for defense, effectively tapping into ant venom as a shared resource.

Scientists investigating Australian stinging trees, for instance, have identified peptides that trigger severe and long-lasting discomfort, mirroring what happens when an animal injects toxins through fangs or barbs.

Fungi and viruses use venom

Fungi have also developed toxin-delivery tactics that come into play when they invade living hosts, and these strategies often involve sophisticated enzymatic activity that breaches protective barriers.

Certain entomopathogenic species, such as Cordyceps fungi, infect insects by using specialized structures to pierce the exoskeleton, then introduce chemical compounds that cripple the insect’s immune response and ultimately pave the way for the fungus to feed.

Viruses might appear too simple to fit our usual venom concepts, but some can inject their genetic material directly into a cell using a needle-like mechanism that disrupts normal function.

This approach even underpins emerging ideas about phage therapy for antibiotic-resistant infections, since bacteriophages can selectively invade harmful bacteria and dismantle them from the inside.

Hidden microbial strategies

Bacterial warfare often revolves around specialized secretory systems that shoot toxins straight into rival cells, effectively seizing control or neutralizing threats on the microbial battlefield.

These intricate setups, including type III and type VI secretion systems, function much like an inbuilt syringe, enabling bacteria to sabotage plant or animal tissues while gaining an upper hand in survival.

Competition among microbes can be fierce, with each species fighting for resources in shared environments, and these hidden battles often hinge on toxin injection that allows one group to dominate a niche.

Some strains even produce contractile devices that resemble phage tails, launching protein payloads across cell membranes to stop competing organisms in their tracks and often developing self-protective measures to avoid collateral damage.

Venom from fungi, plants, and microbes

Medical researchers have long looked to animal venoms for treatments that range from blood pressure medication to pain relief, leveraging the finely tuned molecules that evolved to subdue prey or fend off enemies. These endeavors fuel optimism about searching for new leads among non-animal toxins. 

If plants, fungi, and microbes also contain potent substances shaped by similar evolutionary pressures, then a bigger repository of chemical compounds could emerge for developing therapies against infections, chronic pain, or even cancer.

Adopting a more inclusive perspective on what qualifies as venom might shift the way scientists collaborate across disciplines, bringing together botanists, microbiologists, and pharmacologists in shared discovery that breaks conventional boundaries.

This approach could spark fresh ideas about the ecological roles of toxins in nature, pave the way for advanced drug development pipelines, and spur new methods for controlling pests or pathogens.

The research reminds us that the line between harmful and helpful can be surprisingly thin when viewed through a different lens.

The study is published in the journal Toxins.

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