Cell-type-specific activation of broadly perceived effector-triggered immunity restricts pathogen invasion in plants.

Abstract

Effector-triggered immunity (ETI) is central in plant defense, but whether all cell types execute ETI similarly remains unknown. We combined chemically imposed immune activation with single-cell transcriptomics to profile ETI responses across major leaf cell types in Arabidopsis. Despite uniform ETI perception, we find divergent transcriptional outputs: a core set of defense genes is broadly induced, while distinct cell types activate specialized immune modules. We infer that immune outputs are shaped not only by immune receptor activation but also by cell identity, transcription factor availability, and chromatin accessibility. We further demonstrate that epidermis-enriched transcriptional regulators are required to restrict invasion by non-adapted pathogens. Their absence permits pathogen entry into deeper tissues despite intact recognition, revealing a spatial division of immune functions. Our findings uncover a layered immune architecture in plants, challenge the assumption of uniform immune activation, and establish a framework for exploring cell-type-specific resistance logic in multicellular hosts.