title: Modulation of CYP79 genes and glucosinolate profiles in Arabidopsis by defense signaling pathways.
abstract: Glucosinolates are natural plant products that function in the defense toward herbivores and pathogens. Plant defense is regulated by multiple signal transduction pathways in which salicylic acid (SA), jasmonic acid, and ethylene function as signaling molecules. Glucosinolate content was analyzed in Arabidopsis wild-type plants in response to single or combinatorial treatments with methyljasmonate (MeJA), 2,6-dichloro-isonicotinic acid, ethylene, and 2,4-dichloro-phenoxyacetic acid, or by wounding. In addition, several signal transduction mutants and the SA-depleted transgenic NahG line were analyzed. In parallel, expression of glucosinolate biosynthetic genes of the CYP79 gene family and the UDPG:thiohydroximate glucosyltransferase was monitored. After MeJA treatment, the amount of indole glucosinolates increased 3- to 4-fold, and the corresponding Trp-metabolizing genes CYP79B2 and CYP79B3 were both highly induced. Specifically, the indole glucosinolate N-methoxy-indol-3-ylmethylglucosinolate accumulated 10-fold in response to MeJA treatment, whereas 4-methoxy-indol-3-ylmethylglucosinolate accumulated 1.5-fold in response to 2,6-dichloro-isonicotinic acid. In general, few changes were seen for the levels of aliphatic glucosinolates, although increases in the levels of 8-methylthiooctyl glucosinolate and 8-methylsulfinyloctyl glucosinolate were observed, particularly after MeJA treatments. The findings were supported by the composition of glucosinolates in the coronatine-insensitive mutant coi1, the ctr1 mutant displaying constitutive triple response, and the SA-overproducing mpk4 and cpr1 mutants. The present data indicate that different indole glucosinolate methoxylating enzymes are induced by the jasmonate and the SA signal transduction pathways, whereas the aliphatic glucosinolates appear to be primarily genetically and not environmentally controlled. Thus, different defense pathways activate subsets of biosynthetic enzymes, leading to the accumulation of specific glucosinolates.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant Biology, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, opgang 10, st, DK-1871 Frederiksberg C, Copenhagen, Denmark.
authors.forename: Michael Dalgaard
authors.initials: MD
authors.lastname: Mikkelsen
authors.forename: Bent Larsen
authors.initials: BL
authors.lastname: Petersen
authors.forename: Erich
authors.initials: E
authors.lastname: Glawischnig
authors.forename: Anders Bøgh
authors.initials: AB
authors.lastname: Jensen
authors.forename: Erik
authors.initials: E
authors.lastname: Andreasson
authors.forename: Barbara Ann
authors.initials: BA
authors.lastname: Halkier
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D000085:Acetates / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D005030:Ethylenes / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005961:Glucosinolates / Q000378:metabolism*; D007113:Immunity, Innate; D007210:Indoleacetic Acids / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007539:Isonicotinic Acids / Q000494:pharmacology; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D054883:Oxylipins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D013314:Stress, Mechanical
chemical_list: D000085:Acetates; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D005030:Ethylenes; D005961:Glucosinolates; D007210:Indoleacetic Acids; D007527:Isoenzymes; D007539:Isonicotinic Acids; D054883:Oxylipins; D015084:2,4-Dichlorophenoxyacetic Acid; C077261:2,6-dichloroisonicotinic acid; C072239:methyl jasmonate; D003577:Cytochrome P-450 Enzyme System; C036216:ethylene; D006899:Mixed Function Oxygenases; C089817:cytochrome P450TYR