A report in Biology Letters shows that the drool of herbivores might help defeat the toxic fungal defences of the plants they graze on.
Grazing or cutting some plants induces a noxious chemical to be produced which deters hungry plant-eaters from revisiting them. The chemicals, called alkaloids, are produced by fungi that have a mutually beneficial relationship with the plant.
One such symbiotic relationship is between the grass red fescue and the fungus it plays host to: Epichloë festcuae. The fungus produces the highly toxic alkaloid ergovaline when the plant is wounded, which if consumed can cause disease which might lead to loss of a limb. Evolutionary pressure favours grazers who can chomp their way through the grasses while avoiding these nasty consequences.
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