MIK2 clade receptor function in perception of a Fusarium-derived elicitor is conserved among different plant families

Plants constantly monitor their environment to adapt to potential threats to their health and fitness. This involves cell-surface receptors that can detect conserved microbe-associated molecular patterns (MAMPs) or endogenous immunogenic signals, initiating signaling pathways to induce broad-spectrum disease resistance, known as pattern-triggered immunity (PTI). In Arabidopsis thaliana, the leucine-rich repeat receptor kinase (LRR-RK) MIK2 is an exceptionally versatile receptor involved in the perception of the vast family of Brassicales-specific endogenous SCOOP peptides as well as potential MAMPs derived from Fusarium and related fungi. Although only plant species belonging to the order of Brassicales encode genes for SCOOP peptides and show SCOOP-responsiveness, the Fusarium-derived elicitor fraction also induces PTI responses in plants from other lineages. In this study, we demonstrate that Fusarium elicitor-responsiveness and proteins belonging to the MIK2-clade are widely conserved among seed plants. We identified a MIK2-clade protein from tomato, which shares properties of AtMIK2 in the perception of the Fusarium elicitor but not of SCOOP peptides. Tomato mutants lacking the receptor show compromised PTI responses to the fungal elicitor and enhanced susceptibility to infection by Fusarium oxysporum. Our data provide insights into the evolutionary trajectory of MIK2 as a multifunctional receptor involved in plant immunity.