title: Accumulation of hydroxycinnamic acid amides induced by pathogen infection and identification of agmatine coumaroyltransferase in Arabidopsis thaliana.
abstract: Hydroxycinnamic acid amides (HCAAs) are secondary metabolites involved in the defense of plants against pathogens. Here, we report the first identification of HCAAs, p-coumaroylagmatine, feruloylagmatine, p-coumaroylputrescine and feruloylputrescine, in Arabidopsis thaliana rosette leaves infected with Alternaria brassicicola and the assignment of At5g61160 as the agmatine coumaroyltransferase (AtACT) that catalyzes the last reaction in the biosynthesis of the HCAAs. Feeding experiments with putative labeled precursors revealed that the four HCAAs were synthesized from hydroxycinnamic acids and agmatine or putrescine. AtACT gene function was identified from an analysis of a mutant that did not accumulate HCAAs. In wild-type Arabidopsis, AtACT transcripts markedly increased in response to A. brassicicola infection. Enzymatic activity that catalyzes the synthesis of the HCAAs was confirmed in vitro by using a recombinant AtACT expressed in Escherichia coli. The Atact mutant was susceptible to infection by A. brassicicola, indicating that HCAAs are responsible for defense against pathogens in A. thaliana.
authors.affiliation: Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan. muroi@kais.kyoto-u.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Muroi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ishihara
authors.forename: Chihiro
authors.initials: C
authors.lastname: Tanaka
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ishizuka
authors.forename: Junji
authors.initials: J
authors.lastname: Takabayashi
authors.forename: Hideto
authors.initials: H
authors.lastname: Miyoshi
authors.forename: Takaaki
authors.initials: T
authors.lastname: Nishioka
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000577:Amides / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003373:Coumaric Acids / Q000378:metabolism*; D017931:DNA Primers; D017343:Genes, Plant; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053719:Tandem Mass Spectrometry
chemical_list: D000577:Amides; D003373:Coumaric Acids; D017931:DNA Primers; D012333:RNA, Messenger; D000217:Acyltransferases; C474024:agmatine coumaroyltransferase