Biotic Stress/Applied Plant Bio
CS-23-3 - Translation Regulator GCN2 controls ABA Homeostasis and Stomatal Immunity in Arabidopsis
Tuesday, July 17
9:13 AM - 9:33 AM
Upon pathogen challenge, plants rapidly redirect cellular resources from growth to defense by inducing defense-related gene expression, either at transcriptional or translational level. General Control Non-derepressible 2 (GCN2) is an evolutionarily conserved serine/threonine protein kinase that plays an essential role in modulating amino acid metabolism in response to nutrient deprivation in yeast, human and other eukaryotes. GCN2 binds to uncharged tRNAs, leading to phosphorylation of eukaryotic Initiation Factor 2a. These events trigger a global translational repression but stimulate translation of selective mRNAs that contain upstream open reading frames. Here, we demonstrate that in Arabidopsis, bacterial infection activates the AtGCN2-eIF2a pathway, which consequently reinitiates the translation of a defense-related transcription factor TBF1. We discovered that AtGCN2 regulates a subset of ABA signaling components through TBF1-dependent transcription. While the roles of ABA in pre-invasive and post-invasive defenses have been proposed, it remains to be determined how virulent bacterial pathogens might manipulate this phytohormone to induce effective defenses or establish host susceptibility during pathogen infection. Here, we provide a missing link describing how GCN2 fine-tunes the accumulation of ABA and ABA-mediated signaling players during the pre-invasive and post-invasive stages of an infection event. Finally, we also show that AtGCN2 is required for the perception of phytotoxin coronatine secreted by P. syringae. During the pre-invasive stage, AtGCN2 regulates stomatal immunity by affecting the pathogen-triggered stomatal closure and coronatine-mediated stomatal reopening. Our conclusions suggest a conserved and ancient role of GCN2 in various forms of immune responses across kingdoms, highlighting AtGCN2 as a molecule of key interest in studies on both plant and mammalian immunology.
Xiaoyu Liu – University of Alabama at Birmingham