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UNRAVELING THE MYSTERIES OF PLANT DEFENSE HORMONES: METHYL JASMONATE SIGNALING

Abstract

Understanding how plants defend themselves against various stressors, such as pathogens and herbivores, is critical to a sustainable food supply. Though lacking a defined immune system, plants have developed a remarkable array of structural and biochemical defenses, including one of the most versatile plant hormones, Methyl Jasmonate (MeJA), which is actively engaged in defense against different types of abiotic and biotic stresses. While the studies involved in MeJA mediated defense responses have been majorly focused on transcriptional management (DNA to messenger RNA), the details of a much faster regulation, translational control (messenger RNA to protein), remain unknown. My work investigates how a specific protein kinase, General Control Nonderepressible 2 (GCN2), phosphorylates its target, eukaryotic initiation factor 2 (eIF2) alpha, in response to MeJA at the translational level in the wild type versus transgenic lines of plant model, Arabidopsis thaliana. The GCN2-eIF2alpha module is a highly conserved eukaryotic stress response mode for regulating translation in all eukaryotes. Using immunoblotting, we check for eIF2alpha phosphorylation levels (a proxy for GCN2 activity) under mock and MeJA treatments. We show that eIF2alpha is phosphorylated in response to MeJA treatment in a GCN2-dependent manner. In addition, a homozygous knock out mutant for the GCN2 gene shows reduced growth under prolonged MeJA stress, suggesting GCN2-eIF2alpha as an essential component of the MeJA signaling pathway. Ongoing work is focused on understanding the biochemical and molecular events leading to GCN2-eIF2alpha activation in response to MeJA. These results will provide deeper understanding of MeJA signaling in plants and aid in the future development of plants with better stress resilience/adaptation.

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