Methyl Jasmonate Stress Signaling in Arabidopsis thaliana Functions Via Reactive Oxygen to Activate the GCN2-eIF2α Module
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Authors
Rincon Diaz, Daniel
Issue Date
2024-07-19
Type
Thesis
Language
en_US
Keywords
Biology , Academic theses , Protein biosynthesis , Protein kinases , Plant hormones , Jasmonic acid , Plants—Effect of stress on , Plants—Environmental aspects
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Abstract
Plant growth and productivity rely on rapid energy management strategies designed to cope with dynamic environmental conditions (e.g., fluctuating light intensities, temperature, humidity, and pathogen interactions). Previous work by Lokdarshi et al. (2020a), identified a novel fast-regulatory switch in Arabidopsis thaliana that functions at the nexus of two fundamental energy management programs, cytosolic translation and reactive oxygen species (ROS) signaling. The work showed that the General Control of Nonderepressible 2 (GCN2), a cytosolic serine/threonine protein kinase, is rapidly activated in response to ROS emanating under a variety of abiotic, biotic, and xenobiotic stresses. GCN2 then phosphorylates its target, α-subunit of the eukaryotic translation initiation factor (eIF)2, resulting in readjustments to the active protein synthesis, as a plausible mode for stress remediation. In the work presented here, we test the hypothesis that the biochemical, molecular and physiological responses of the Arabidopsis GCN2-eIF2α module towards the plant defense hormone, methyl jasmonate (MeJA) is regulated by light and ROS. We show that eIF2α phosphorylation (PeIF2α) as proxy for GCN2 activation under MeJA stress requires light and this activation can be mitigated with antioxidants and photosynthetic inhibitors. At the physiological level, gcn2 mutant seedlings show increased sensitivity towards MeJA stress in a primary root growth assay. Interestingly, the gcn2 mutant shows a similar rate of protein synthesis as the wild-type under MeJA stress as evidenced by polysome profiling and puromycin incorporation assay. Taken together, we show the conservation of Arabidopsis GCN2-eIF2α activation by ROS during methyl jasmonate stress.
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This dissertation is protected by the Copyright Laws of the United States (Public Law 94-553, revised in 1976). Consistent with fair use as defined in the Copyright Laws, brief quotations from this material are allowed with proper acknowledgement. Use of the materials for financial gain with the author's expressed written permissions is not allowed.