title: Intronic T-DNA insertion renders Arabidopsis opr3 a conditional jasmonic acid-producing mutant.
abstract: Jasmonic acid and its derived metabolites (JAs) orchestrate plant defense against insects and fungi. 12-Oxo-phytodienoic acid (OPDA), a JA precursor, has also been implicated in plant defense. We sought to define JAs and OPDA functions through comparative defense susceptibility characteristics of three Arabidopsis (Arabidopsis thaliana) genotypes: aos, lacking JAs and OPDA; opda reductase3 (opr3), deficient in JA production but can accumulate OPDA; and transgenics that overexpress OPR3. opr3, like aos, is susceptible to cabbage loopers (Trichoplusia ni) but, relative to aos, opr3 has enhanced resistance to a necrotrophic fungus. Gas chromatography-mass spectrometry reveals that opr3 produces OPDA but no detectable JAs following wounding and looper infestation; unexpectedly, substantial levels of JAs accumulate in opr3 upon fungal infection. Full-length OPR3 transcripts accumulate in fungal-infected opr3, potentially through splicing of the T-DNA containing intron. Fungal resistance correlates with levels of JAs not OPDA; therefore, opr3 resistance to some pests is likely due to JA accumulation, and signaling activities ascribed to OPDA should be reassessed because opr3 can produce JAs. Together these data (1) reinforce the primary role JAs play in plant defense against insects and necrotrophic fungi, (2) argue for a reassessment of signaling activities ascribed to OPDA, and (3) provide evidence that mutants with intron insertions can retain gene function.
authors.affiliation: Rice University, Houston, Texas 77005, USA.
authors.forename: E Wassim
authors.initials: EW
authors.lastname: Chehab
authors.forename: Se
authors.initials: S
authors.lastname: Kim
authors.forename: Tatyana
authors.initials: T
authors.lastname: Savchenko
authors.forename: Daniel
authors.initials: D
authors.lastname: Kliebenstein
authors.forename: Katayoon
authors.initials: K
authors.lastname: Dehesh
authors.forename: Janet
authors.initials: J
authors.lastname: Braam
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology / Q000382:microbiology / Q000469:parasitology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D020171:Botrytis / Q000187:drug effects / Q000502:physiology; D001937:Brassica / Q000469:parasitology; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005298:Fertility / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects / Q000276:immunology; D007211:Indoles / Q000378:metabolism; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D009036:Moths / Q000187:drug effects / Q000502:physiology; D016254:Mutagenesis, Insertional / Q000187:drug effects / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D054883:Oxylipins / Q000378:metabolism* / Q000494:pharmacology; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology / Q000469:parasitology; D013844:Thiazoles / Q000378:metabolism; D000094162:Phytoalexins
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D004269:DNA, Bacterial; D005231:Fatty Acids, Unsaturated; D007211:Indoles; D010088:Oxidoreductases; D054883:Oxylipins; D013844:Thiazoles; C036483:T-DNA; C102405:camalexin; D000094162:Phytoalexins; C025999:12-oxophytodienoic acid; C011006:jasmonic acid; C416525:OPR3 protein, Arabidopsis