We previously reported that coronatine, a virulence factor of plant bacteria, facilitates bacterial infection through an ER (endoplasmic reticulum)-mediated, non-canonical mechanism in the model dicot plant, Arabidopsis thaliana. Here, we report that this same ER-mechanism is ubiquitous among dicots and monocots, and works by affecting the ethylene signaling pathway widely found in plants. The subcellular localization of coronatine by the alkyne-tag Raman imaging (ATRI) approach provided a convincing clue.