A study has unraveled a mystery that persisted for fifty years in plant science – the elusive role of Pathogenesis-Related Protein 1 (PR1) in plant immunity. Led by Dr. Yet-Ran Chen at the Agricultural Biotechnology Research Center, Academia Sinica, this research casts a revealing light on the pivotal mechanism governing the enzymatic transformation of canonical immune biomarker PR1 into a potent CAPE cytokine. This transformation initiates plant systemic acquired resistance (SAR), a critical defense function against pathogenic infection. Remarkably, even plants incapable of synthesizing or perceiving salicylic acid, a central hormone for activating SAR, can activate systemic immunity when exposed to trace amounts of CAPE. This achievement serves as a foundation for enhancing crops' resilience against diseases and introduces novel perspectives for mitigating the adverse effects of global warming on plant immunity. This study has been published in the journal Nature Communications (August 2023).