title: The Synthetic Elicitor 2-(5-Bromo-2-Hydroxy-Phenyl)-Thiazolidine-4-Carboxylic Acid Links Plant Immunity to Hormesis.
abstract: Synthetic elicitors are drug-like compounds that induce plant immune responses but are structurally distinct from natural defense elicitors. Using high-throughput screening, we previously identified 114 synthetic elicitors that activate the expression of a pathogen-responsive reporter gene in Arabidopsis (Arabidopsis thaliana). Here, we report on the characterization of one of these compounds, 2-(5-bromo-2-hydroxy-phenyl)-thiazolidine-4-carboxylic acid (BHTC). BHTC induces disease resistance of plants against bacterial, oomycete, and fungal pathogens and has a unique mode of action and structure. Surprisingly, we found that low doses of BHTC enhanced root growth in Arabidopsis, while high doses of this compound inhibited root growth, besides inducing defense. These effects are reminiscent of the hormetic response, which is characterized by low-dose stimulatory effects of a wide range of agents that are toxic or inhibitory at higher doses. Like its effects on defense, BHTC-induced hormesis in Arabidopsis roots is partially dependent on the WRKY70 transcription factor. Interestingly, BHTC-induced root hormesis is also affected in the auxin-response mutants axr1-3 and slr-1. By messenger RNA sequencing, we uncovered a dramatic difference between transcriptional profiles triggered by low and high doses of BHTC. Only high levels of BHTC induce typical defense-related transcriptional changes. Instead, low BHTC levels trigger a coordinated intercompartmental transcriptional response manifested in the suppression of photosynthesis- and respiration-related genes in the nucleus, chloroplasts, and mitochondria as well as the induction of development-related nuclear genes. Taken together, our functional characterization of BHTC links defense regulation to hormesis and provides a hypothetical transcriptional scenario for the induction of hormetic root growth.
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521.
authors.forename: Melinda
authors.initials: M
authors.lastname: Rodriguez-Salus
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521 ybekt001@ucr.edu thomas.eulgem@ucr.edu.
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Bektas
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Schroeder
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521.
authors.forename: Colleen
authors.initials: C
authors.lastname: Knoth
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521.
authors.forename: Trang
authors.initials: T
authors.lastname: Vu
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521.
authors.forename: Philip
authors.initials: P
authors.lastname: Roberts
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521.
authors.forename: Isgouhi
authors.initials: I
authors.lastname: Kaloshian
authors.affiliation: ChemGen Integrative Graduate Education and Research Traineeship Program (M.R.-S., M.S., C.K., T.E.), Center for Plant Cell Biology, Institute for Integrative Genome Biology (M.R.-S., Y.B., M.S., C.K., I.K., T.E.), Department of Botany and Plant Sciences (M.R.-S., Y.B., M.S., C.K., T.V., T.E.), and Department of Nematology (P.R., I.K.), University of California, Riverside, California 92521 ybekt001@ucr.edu thomas.eulgem@ucr.edu.
authors.forename: Thomas
authors.identifier: http://orcid.org/0000-0002-8421-2988
authors.initials: T
authors.lastname: Eulgem
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000276:immunology* / Q000382:microbiology / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism; D002723:Chlorobenzoates / Q000737:chemistry / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D059165:Hormesis; D054884:Host-Pathogen Interactions / Q000187:drug effects / Q000276:immunology; D044742:Peronospora / Q000472:pathogenicity; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D030821:Plants, Genetically Modified; D013329:Structure-Activity Relationship; D053778:Thiazolidines / Q000276:immunology / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D062367:ortho-Aminobenzoates / Q000737:chemistry / Q000494:pharmacology
chemical_list: C000610874:2-(5-bromo-2-hydroxyphenyl)thiazolidine-4-carboxylic acid; C542164:3,5-dichloroanthranilic acid; C081977:AXR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C542165:CaBP22 protein, Arabidopsis; D002147:Calmodulin; D002723:Chlorobenzoates; D053778:Thiazolidines; D014157:Transcription Factors; C487183:WRKY70 protein, Arabidopsis; D062367:ortho-Aminobenzoates