Dataset Information

EIF2? Phosphorylation by GCN2 Is Induced in the Presence of Chitin and Plays an Important Role in Plant Defense against B. cinerea Infection.

ABSTRACT: Translation plays an important role in plant adaptation to different abiotic and biotic stresses; however, the mechanisms involved in translational regulation during each specific response and their effect in translation are poorly understood in plants. In this work, we show that GCN2 promotes eIF2? phosphorylation upon contact with Botrytis cinerea spores, and that this phosphorylation is required for the proper establishment of plant defense against the fungus. In fact, independent gcn2 mutants display an enhanced susceptibility to B. cinerea infection, which is highlighted by an increased cell death and reduced expression of ethylene- and jasmonic-related genes in the gcn2 mutants. eIF2? phosphorylation is not only triggered in the presence of the fungus, but interestingly, is also achieved in the sole presence of the microbe-associated molecular pattern (MAMP) chitin. Moreover, analysis of de novo protein synthesis by 35SMet-35SCys incorporation indicates that chitin treatment promotes a global inhibition of translation. Taken together, these results suggest that eIF2? phosphorylation by GCN2 is promoted in the presence of chitin and plays an important role in plant defense against B. cinerea infection.

SUBMITTER: Berrocal-Lobo M

PROVIDER: S-EPMC7582497 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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eIF2α Phosphorylation by GCN2 Is Induced in the Presence of Chitin and Plays an Important Role in Plant Defense against B. cinerea Infection.

Berrocal-Lobo Marta M Toribio René R Castellano M Mar MM

International journal of molecular sciences 20201004 19

Translation plays an important role in plant adaptation to different abiotic and biotic stresses; however, the mechanisms involved in translational regulation during each specific response and their effect in translation are poorly understood in plants. In this work, we show that GCN2 promotes eIF2α phosphorylation upon contact with Botrytis cinerea spores, and that this phosphorylation is required for the proper establishment of plant defense against the fungus. In fact, independent g ...[more]

PMID: 33020405

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Project description:GCN2 (general control nonrepressed 2) is a serine/threonine-protein kinase that regulates translation in response to stressors such as amino acid and purin deprivation, cold shock, wounding, cadmium, and UV-C exposure. Activated GCN2 phosphorylates the α-subunit of the eukaryotic initiation factor 2 (eIF2) leading to a drastic inhibition of protein synthesis and shifting translation to specific mRNAs. To investigate the role of GCN2 in responses to UV-B radiation its activity was analyzed through eIF2α phosphorylation assays in mutants of the specific UV-B and stress signaling pathways of Arabidopsis thaliana. EIF2α phosphorylation was detectable 30 min after UV-B exposure, independent of the UV-B photoreceptor UV RESISTANCE LOCUS8 and its downstream signaling components. GCN2 dependent phosphorylation of eIF2α was also detectable in mutants of the stress related MAP kinases, MPK3 and MPK6 and their negative regulator map kinase phosphatase1 (MKP1). Transcription of downstream components of the UV-B signaling pathway, the Chalcone synthase (CHS) was constitutively higher in gcn2-1 compared to wildtype and further increased upon UV-B while GLUTATHIONE PEROXIDASE7 (GPX7) behaved similarly to wildtype. The UVR8 independent FAD-LINKED OXIDOREDUCTASE (FADox) had a lower basal expression in gcn2-1 which was increased upon UV-B. Since high fluence rates of UV-B induce DNA damage the expression of the RAS ASSOCIATED WITH DIABETES PROTEIN51 (RAD51) was quantified before and after UV-B. While the basal expression was similar to wildtype it was significantly less induced upon UV-B in the gcn2-1 mutant. This expression pattern correlates with the finding that gcn2 mutants develop less cyclobutane pyrimidine dimers after UV-B exposure. Quantification of translation with the puromycination assay revealed that gcn2 mutants have an increased rate of translation which was also higher upon UV-B. Growth of gcn2 mutants to chronic UV-B exposure supports GCN2's role as a negative regulator of UV-B responses. The elevated resistance of gcn2 mutants towards repeated UV-B exposure points to a critical role of GCN2 in the regulation of translation upon UV-B.

Project description:BACKGROUND:Isocitrate lyase (ICL) is a key enzyme in the glyoxylate cycle. In a previous study in rice, the expression of the ICL-encoding gene (OsICL) was highly induced by salt stress and its expression was enhanced in transgenic rice lines overexpressing OsCam1-1, a calmodulin (CaM)-encoding gene. CaM has been implicated in salt tolerance mechanisms in plants; however, the cellular mechanisms mediated by CaM are not clearly understood. In this study, the role of OsICL in plant salt tolerance mechanisms and the possible involvement of CaM were investigated using transgenic plants expressing OsICL or OsCam1-1. RESULTS:OsICL was highly expressed in senesced leaf and significantly induced by salt stress in three OsCam1-1 overexpressing transgenic rice lines as well as in wild type (WT). In WT young leaf, although OsICL expression was not affected by salt stress, all three transgenic lines exhibited highly induced expression levels. In Arabidopsis, salt stress had negative effects on germination and seedling growth of the AtICL knockout mutant (Aticl mutant). To examine the roles of OsICL we generated the following transgenic Arabidopsis lines: the Aticl mutant expressing OsICL driven by the native AtICL promoter, the Aticl mutant overexpressing OsICL driven by the 35SCaMV promoter, and WT overexpressing OsICL driven by the 35SCaMV promoter. Under salt stress, the germination rate and seedling fresh and dry weights of the OsICL-expressing lines were higher than those of the Aticl mutant, and the two lines with the icl mutant background were similar to the WT. The Fv/Fm and temperature of rosette leaves in the OsICL-expressing lines were less affected by salt stress than they were in the Aticl mutant. Finally, glucose and fructose contents of the Aticl mutant under salt stress were highest, whereas those of OsICL-expressing lines were similar to or lower than those of the WT. CONCLUSIONS:OsICL, a salt-responsive gene, was characterized in the transgenic Arabidopsis lines, revealing that OsICL expression could revert the salt sensitivity phenotypes of the Aticl knockout mutant. This work provides novel evidence that supports the role of ICL in plant salt tolerance through the glyoxylate cycle and the possible involvement of OsCam1-1 in regulating its transcription.

Dataset Information

EIF2? Phosphorylation by GCN2 Is Induced in the Presence of Chitin and Plays an Important Role in Plant Defense against B. cinerea Infection.

Publications

eIF2α Phosphorylation by GCN2 Is Induced in the Presence of Chitin and Plays an Important Role in Plant Defense against <i>B. cinerea</i> Infection.

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