Arabidopsis thaliana class-II TGA transcription factors are essential activators of jasmonic acid/ethylene-induced defense responses.
The three closely related Arabidopsis basic leucine zipper (bZIP) transcription factors TGA2, TGA5 and TGA6 are required for the establishment of the salicylic acid (SA)-dependent plant defense response systemic acquired resistance, which is effective against biotrophic pathogens. Here we show that the same transcription factors are essential for the activation of jasmonic acid (JA)- and ethylene (ET)-dependent defense mechanisms that counteract necrotrophic pathogens: the tga256 triple mutant is impaired in JA/ET-induced PDF1.2 and b-CHI expression, which correlates with a higher susceptibility against the necrotroph Botrytis cinerea. JA/ET induction of the trans-activators ERF1 and ORA59, which act upstream of PDF1.2, was slightly increased (ERF1) or unaffected (ORA59). PDF1.2 expression can be restored in the tga256 mutant by increased expression of ORA59, as observed in the tga256 jin1 quadruple mutant, which lacks the transcription factor JIN1/AtMYC2 that functions as a negative regulator of the JA/ET-dependent anti-fungal defense program. Whereas JA/ET-induced PDF1.2 expression is strongly suppressed by SA in wild-type plants, no negative effect of SA on PDF1.2 expression was observed in the tga256 jin1 quadruple mutant. These results imply that the antagonistic effects of TGA factors and JIN1/AtMYC2 on the JA/ET pathway are necessary to evoke the SA-mediated suppression of JA/ET-induced defense responses.
Zander
Mark
M
Albrecht-von-Haller-Institut fuer Pflanzenwissenschaften, Georg-August-Universitaet Goettingen, Untere Karspuele 2, D-37073 Goettingen, Germany.
La Camera
Sylvain
S
Lamotte
Olivier
O
Métraux
Jean-Pierre
JP
Gatz
Christiane
C
D017360:Arabidopsis / Q000235:genetics* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics; D020171:Botrytis / Q000254:growth & development; D003517:Cyclopentanes / Q000494:pharmacology*; D023082:Defensins / Q000235:genetics; D005030:Ethylenes / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate / Q000235:genetics; D008957:Models, Genetic; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D054883:Oxylipins / Q000494:pharmacology*; D010454:Peptide Termination Factors / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010937:Plant Growth Regulators / Q000494:pharmacology; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D003517:Cyclopentanes; D023082:Defensins; D005030:Ethylenes; D009687:Nuclear Proteins; D054883:Oxylipins; D010454:Peptide Termination Factors; D010937:Plant Growth Regulators; D015534:Trans-Activators; D014157:Transcription Factors; C489413:AHBP-1b protein, Arabidopsis; C473611:MYC2 protein, Arabidopsis; C084751:OBF5 protein, Arabidopsis; C531343:ORA59 protein, Arabidopsis; C487542:At5g44420 protein, Arabidopsis; C107090:TGA6 protein, Arabidopsis; C494978:eukaryotic release factor 1, Arabidopsis; C011006:jasmonic acid; C036216:ethylene