title: Salicylic acid inhibits pathogen growth in plants through repression of the auxin signaling pathway.
abstract: The phytohormone auxin regulates almost every aspect of plant development. At the molecular level, auxin induces gene expression through direct physical interaction with the TIR1-like F box proteins, which in turn remove the Aux/IAA family of transcriptional repressors [1-4]. A growing body of evidence indicates that many plant pathogens can either produce auxin themselves or manipulate host auxin biosynthesis to interfere with the host's normal developmental processes [5-11]. In response, plants probably evolved mechanisms to repress auxin signaling during infection as a defense strategy. Plants overaccumulating the defense signal molecule salicylic acid (SA) frequently display morphological phenotypes that are reminiscent of auxin-deficient or auxin-insensitive mutants, indicating that SA might interfere with auxin responses. By using the Affymetrix ATH1 GeneChip for Arabidopsis thaliana, we performed a comprehensive study of the effects of SA on auxin signaling [12]. We found that SA causes global repression of auxin-related genes, including the TIR1 receptor gene, resulting in stabilization of the Aux/IAA repressor proteins and inhibition of auxin responses. We demonstrate that this inhibitory effect on auxin signaling is a part of the SA-mediated disease-resistance mechanism.
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Karolina
authors.initials: K
authors.lastname: Pajerowska-Mukhtar
authors.forename: Angela Hendrickson
authors.initials: AH
authors.lastname: Culler
authors.forename: Xinnian
authors.initials: X
authors.lastname: Dong
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D020869:Gene Expression Profiling; D017343:Genes, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010935:Plant Diseases / Q000235:genetics; D010937:Plant Growth Regulators / Q000502:physiology; D030821:Plants, Genetically Modified; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013830:Thiadiazoles / Q000494:pharmacology
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D013830:Thiadiazoles; C099403:S-methyl benzo(1,2,3)thiadiazole-7-carbothioate; D020156:Salicylic Acid