Journal Article

TGA transcription factors and jasmonate-independent COI1 signalling regulate specific plant responses to reactive oxylipins

Mueller, Stefan, Zoeller, Maria, Stotz, Henrik U, Mueller, Martin J, Berger, Susanne

2013

Overview

Jasmonates and phytoprostanes are oxylipins that regulate stress responses and diverse physiological and developmental processes. 12-Oxo-phytodienoic acid (OPDA) and phytoprostanes are structurally related electrophilic cyclopentenones, which activate similar gene expression profiles that are for the most part different from the action of the cyclopentanone jasmonic acid (JA) and its biologically active amino acid conjugates. Whereas JA–isoleucine signals through binding to COI1, the bZIP transcription factors TGA2, TGA5, and TGA6 are involved in regulation of gene expression in response to phytoprostanes. Here root growth inhibition and target gene expression were compared after treatment with JA, OPDA, or phytoprostanes in mutants of the COI1/MYC2 pathway and in different TGA factor mutants. Inhibition of root growth by phytoprostanes was dependent on COI1 but independent of jasmonate biosynthesis. In contrast, phytoprostane-responsive gene expression was strongly dependent on TGA2, TGA5, and TGA6, but not dependent on COI1, MYC2, TGA1, and TGA4. Different mutant and overexpressing lines were used to determine individual contributions of TGA factors to cyclopentenone-responsive gene expression. Whereas OPDA-induced expression of the cytochrome P450 gene CYP81D11 was primarily regulated by TGA2 and TGA5, the glutathione S-transferase gene GST25 and the OPDA reductase gene OPR1 were regulated by TGA5 and TGA6, but less so by TGA2. These results support the model that phytoprostanes and OPDA regulate differently (i) growth responses, which are COI1 dependent but jasmonate independent; and (ii) lipid stress responses, which are strongly dependent on TGA2, TGA5, and TGA6. Identification of molecular components in cyclopentenone signalling provides an insight into novel oxylipin signal transduction pathways.

• Publisher: Oxford University Press [etc.],Oxford University Press
• Subject: amino acids / Arabidopsis / Arabidopsis - genetics / Arabidopsis - growth & development / Arabidopsis - metabolism / Arabidopsis Proteins / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Basic-Leucine Zipper Transcription Factors / Basic-Leucine Zipper Transcription Factors - genetics / Basic-Leucine Zipper Transcription Factors - metabolism / Biological and medical sciences / Biosynthesis / Cyclopentanes / Cyclopentanes - metabolism / Cyclopentanes - pharmacology / cytochrome P-450 / Cytochrome P-450 Enzyme System / Cytochrome P-450 Enzyme System - genetics / Cytochrome P-450 Enzyme System - metabolism / drug effects / Fatty Acids, Unsaturated / Fatty Acids, Unsaturated - pharmacology / Fundamental and applied biological sciences. Psychology / Gene expression / Gene expression regulation / Gene Expression Regulation, Plant / gene overexpression / Genes / Genes, Plant / genetics / glutathione transferase / growth & development / growth retardation / Isoleucine / Isoleucine - metabolism / jasmonic acid / metabolism / mutants / Nuclear Proteins / Nuclear Proteins - genetics / Nuclear Proteins - metabolism / oxylipins / Oxylipins - metabolism / Oxylipins - pharmacology / pharmacology / Plant cells / Plant physiology and development / plant response / Plant Roots / Plant Roots - drug effects / Plant Roots - growth & development / Plant Roots - metabolism / Plants / Plants, Genetically Modified / Plants, Genetically Modified - genetics / Plants, Genetically Modified - growth & development / Plants, Genetically Modified - metabolism / Prostaglandins A / Prostaglandins A - pharmacology / RESEARCH PAPER / RNA / Root growth / Seedlings / Signal Transduction / stress response / Stress, Physiological / Transcription factors / Transcription, Genetic / Transcriptome