Synthetic FLS2 receptor oligomer boosts plant innate immunity.

The gradual assembly and oligomerization of cell surface receptors are critical for regulating immune activation and turnover. Yet, how dynamic, spatiotemporally regulated assembly enables rapid and sustained signaling in plant innate immunity remains unclear, owing to the inherent complexity of their dynamic associations. Using a synthetic engineering approach, we precisely controlled the oligomerization states of the Arabidopsis FLS2 receptor. Single-particle imaging with quantitative calibration revealed that FLS2 transits from a predominantly monomeric resting state to transient homo-association at dimeric configuration upon activation. We then showed that synthetically engineered receptor homo-dimeric association markedly enhances plant defense responses while avoids dysfunctional high-order assemblies, which inhibit dynamic receptor replenishment and thus defect in long-lasting immune activities. Our findings highlight precise receptor assembly control for both immediate activation and long-term signaling, offering strategies for engineering durable plant immune responses.