title: The synthetic elicitor 3,5-dichloroanthranilic acid induces NPR1-dependent and NPR1-independent mechanisms of disease resistance in Arabidopsis.
abstract: Immune responses of Arabidopsis (Arabidopsis thaliana) are at least partially mediated by coordinated transcriptional up-regulation of plant defense genes, such as the Late/sustained Up-regulation in Response to Hyaloperonospora parasitica (LURP) cluster. We found a defined region in the promoter of the LURP member CaBP22 to be important for this response. Using a CaBP22 promoter-reporter fusion, we have established a robust and specific high-throughput screening system for synthetic defense elicitors that can be used to trigger defined subsets of plant immune responses. Screening a collection of 42,000 diversity-oriented molecules, we identified 114 candidate LURP inducers. One representative, 3,5-dichloroanthranilic acid (DCA), efficiently induced defense reactions to the phytopathogens H. parasitica and Pseudomonas syringae. In contrast to known salicylic acid analogs, such as 2,6-dichloroisonicotinic acid (INA), which exhibit a long-lasting defense-inducing activity and are fully dependent on the transcriptional cofactor NPR1 (for Nonexpresser of Pathogenesis-Related genes1), DCA acts transiently and is only partially dependent on NPR1. Microarray analyses revealed a cluster of 142 DCA- and INA-responsive genes that show a pattern of differential expression coinciding with the kinetics of DCA-mediated disease resistance. These ACID genes (for Associated with Chemically Induced Defense) constitute a core gene set associated with chemically induced disease resistance, many of which appear to encode components of the natural immune system of Arabidopsis.
authors.affiliation: Center for Plant Cell Biology, Institute for Integrative Genome Biology, Department of Botany and Plant Sciences, University of California at Riverside, Riverside, California 92521, USA.
authors.forename: Colleen
authors.initials: C
authors.lastname: Knoth
authors.forename: Melinda S
authors.initials: MS
authors.lastname: Salus
authors.forename: Thomas
authors.initials: T
authors.lastname: Girke
authors.forename: Thomas
authors.initials: T
authors.lastname: Eulgem
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002147:Calmodulin / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002723:Chlorobenzoates; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017930:Genes, Reporter; D007113:Immunity, Innate / Q000235:genetics; D007700:Kinetics; D005810:Multigene Family; D020411:Oligonucleotide Array Sequence Analysis; D009868:Oomycetes / Q000254:growth & development; D011401:Promoter Regions, Genetic; D044224:Pseudomonas syringae / Q000254:growth & development; D011993:Recombinant Fusion Proteins / Q000032:analysis; D020156:Salicylic Acid / Q000494:pharmacology; D062367:ortho-Aminobenzoates / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C542164:3,5-dichloroanthranilic acid; D029681:Arabidopsis Proteins; C542165:CaBP22 protein, Arabidopsis; D002147:Calmodulin; D002723:Chlorobenzoates; C105496:NPR1 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D062367:ortho-Aminobenzoates; D020156:Salicylic Acid