Plant herbivore protection by arbuscular mycorrhizas : a role for fungal diversity?

The symbiosis between arbuscular mycorrhizal (AM) fungi, subphylum Glomeromycotina, and terrestrial plants is one of the most widespread and arguably most successful plant symbioses on Earth. This ancient relationship, going back 475 MY (Remy et al., 1994; Redecker & Raab, 2006; Field et al., 2015; Rich et al., 2021) is beneficial for the fungi and normally benefits their plant partners. Through colonisation of plant roots, the fungi provide their host plants with access to soil elements including phosphorus (P) and nitrogen (N) while the fungi are provided with carbon (Hodge et al., 2001; Smith & Read, 2008; Keymer & Gutjahr, 2018). The contribution of AM fungi to ecosystems goes beyond nutrient delivery to plants.