TGA transcription factors and jasmonate-independent COI1 signalling regulate specific plant responses to reactive oxylipins.
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.
Julius-von-Sachs-Institute für Biowissenschaften, Pharmazeutische Biologie, Universität Würzburg, Würzburg, Germany. h.stotz@herts.ac.uk
Henrik U
HU
Stotz
Stefan
S
Mueller
Maria
M
Zoeller
Martin J
MJ
Mueller
Susanne
S
Berger
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007532:Isoleucine / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011454:Prostaglandins A / Q000494:pharmacology; D015398:Signal Transduction; D013312:Stress, Physiological; D014158:Transcription, Genetic; D059467:Transcriptome
C489413:AHBP-1b protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; D005231:Fatty Acids, Unsaturated; D009687:Nuclear Proteins; C084751:OBF5 protein, Arabidopsis; D054883:Oxylipins; D011454:Prostaglandins A; D007532:Isoleucine; C025999:12-oxophytodienoic acid; C011006:jasmonic acid; D003577:Cytochrome P-450 Enzyme System; C013905:cyclopentenone; C100573:prostaglandin A1