Identification of two Arabidopsis genes encoding a peroxisomal oxidoreductase-like protein and an acyl-CoA synthetase-like protein that are required for responses to pro-auxins.
Indole-3-butyric acid (IBA) and 2,4-dichlorophenoxybutyric acid (2,4-DB) are metabolised by peroxisomal beta-oxidation to active auxins that inhibit root growth. We screened Arabidopsis mutants for resistance to IBA and 2,4-DB and identified two new 2,4-DB resistant mutants. The mutant genes encode a putative oxidoreductase (SDRa) and a putative acyl-activating enzyme (AAE18). Both proteins are localised to peroxisomes. SDRa is coexpressed with core beta-oxidation genes, but germination, seedling growth and the fatty acid profile of sdra seedlings are indistinguishable from wild type. The sdra mutant is also resistant to IBA, but aae18 is not. AAE18 is the first example of a gene required for response to 2,4-DB but not IBA. The closest relative of AAE18 is AAE17. AAE17 is predicted to be peroxisomal, but an aae17 aae18 double mutant responded similarly to aae18 for all assays. We propose that AAE18 is capable of activating 2,4-DB but IBA activating enzymes remain to be discovered. We present an updated model for peroxisomal pro-auxin metabolism in Arabidopsis that includes SDRa and AAE18.
Wiszniewski
Andrew A G
AA
University of Western Australia, Crawley, WA 6009, Australia.
Zhou
Wenxu
W
Smith
Steven M
SM
Bussell
John D
JD
D015084:2,4-Dichlorophenoxyacetic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000429:Alcohol Oxidoreductases / Q000235:genetics*; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003066:Coenzyme A Ligases / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004351:Drug Resistance / Q000187:drug effects; D005227:Fatty Acids / Q000378:metabolism; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction / Q000187:drug effects; D020675:Peroxisomes / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D010641:Phenotype; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D021381:Protein Transport / Q000187:drug effects; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D013395:Sucrose / Q000494:pharmacology
D015084:2,4-Dichlorophenoxyacetic Acid; D000429:Alcohol Oxidoreductases; D029681:Arabidopsis Proteins; D003066:Coenzyme A Ligases; D004269:DNA, Bacterial; D005227:Fatty Acids; D007210:Indoleacetic Acids; D007211:Indoles; D013395:Sucrose; C036483:T-DNA; C014612:indolebutyric acid; C540059:IBR1 protein, Arabidopsis; C540060:AAE18 protein, Arabidopsis; C004764:4-(2,4-dichlorophenoxy)butyric acid