The WRKY70 transcription factor: a node of convergence for jasmonate-mediated and salicylate-mediated signals in plant defense.
Cross talk between salicylic acid (SA)- and jasmonic acid (JA)-dependent defense signaling has been well documented in plants, but how this cross talk is executed and the components involved remain to be elucidated. We demonstrate that the plant-specific transcription factor WRKY70 is a common component in SA- and JA-mediated signal pathways. Expression of WRKY70 is activated by SA and repressed by JA. The early induction of WRKY70 by SA is NPR1-independent, but functional NPR1 is required for full-scale induction. Epistasis analysis suggested that WRKY70 is downstream of NPR1 in an SA-dependent signal pathway. Modulation of WRKY70 transcript levels by constitutive overexpression increases resistance to virulent pathogens and results in constitutive expression of SA-induced pathogenesis-related genes. Conversely, antisense suppression of WRKY70 activates JA-responsive/COI1-dependent genes. The effect of WRKY70 is not caused by subsequent changes in SA or JA levels. We suggest that WRKY70 acts as an activator of SA-induced genes and a repressor of JA-responsive genes, integrating signals from these mutually antagonistic pathways.
Li
Jing
J
Department of Biosciences, Division of Genetics, University of Helsinki, FIN-00014 Helsinki, Finland.
Brader
Günter
G
Palva
E Tapio
ET
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D054883:Oxylipins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000235:genetics* / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D029681:Arabidopsis Proteins; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; D005030:Ethylenes; C105496:NPR1 protein, Arabidopsis; D054883:Oxylipins; D010940:Plant Proteins; D014157:Transcription Factors; C487183:WRKY70 protein, Arabidopsis; C499621:ZAP1 protein, Arabidopsis; C011006:jasmonic acid; C036216:ethylene; D020156:Salicylic Acid