Common mycelial network modulates neighbour-primed plant defences against foliar pathogens by co-opting distinct inter-plant metabolic and biotic stress responses.

Arbuscular mycorrhizal fungi (AMF) are ubiquitous root symbionts, well-known to constitute underground common mycelial networks (CMNs) linking multiple plant hosts underground. The wired connection among plants via CMNs are hypothesized to play a key role for information exchange between plants for the neighbour-primed inter-plant defences.

However, the key transcriptomic and metabolome responses in receiver plant associated with inter-plant CMN connections remain yet to be elucidated. Moreover, no studies to date have clearly resolved the confounding effects of hyphal damage from the inter-plant network disconnection. To uncover the contribution of CMN integrity to neighbour-primed plant defences, we used model AMF Rhizophagus irregularis to inter-connect two Medicago truncatula plants and explored the effect of sender wounding and flg22 elicitation on receiver plants’ leaf responses and pathogen tolerance.