Methyl Transfer in Glucosinolate Biosynthesis Mediated by Indole Glucosinolate O-Methyltransferase 5. Issue 4 (3rd November 2016)

• Record Type: Journal Article
• Authors: Pfalz, Marina; Mukhaimar, Maisara; Perreau, François; Kirk, Jayne; Hansen, Cecilie Ida Cetti; Olsen, Carl Erik; Agerbirk, Niels; Kroymann, Juergen
• Is Part Of: Plant physiology. Volume 172:Issue 4(2016)
• Page Start: 2190
• Page End: 2203
• Publication Date: 2016-11-03
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.16.01402
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : Indole glucosinolate O-methyltransferase 5 catalyzes the methyl transfer reaction in the biosynthesis of Trp-derived glucosinolates that are modified at position 1 of the indole ring. Abstract: Indole glucosinolates (IG s) are plant secondary metabolites that are derived from the amino acid tryptophan. The product of Arabidopsis ( Arabidopsis thaliana ) IG core biosynthesis, indol-3-ylmethyl glucosinolate (I3M), can be modified by hydroxylation and subsequent methoxylation of the indole ring in position 1 (1-IG modification) or 4 (4-IG modification). Products of the 4-IG modification pathway mediate plant-enemy interactions and are particularly important for Arabidopsis innate immunity. While CYP81F s encoding cytochrome P450 monooxygenases and IGMT s encoding indole glucosinolate O -methyltransferases have been identified as key genes for IG modification, our knowledge about the IG modification pathways is not complete. In particular, it is unknown which enzyme is responsible for methyl transfer in the 1-IG modification pathway and whether this pathway plays a role in defense, similar to 4-IG modification. Here, we analyze two Arabidopsis transfer DNA insertion lines with targeted metabolomics. We show that biosynthesis of 1-methoxyindol-3-ylmethyl glucosinolate (1MOI3M) from I3M involves the predicted unstable intermediate 1-hydroxyindol-3-ylmethyl glucosinolate (1OHI3M) and that IGMT5, a gene with moderate similarity to previously characterized IGMT s, encodes the methyltransferase that is responsible for the conversion of 1OHI3M to 1MOI3M. Disruption of IGMT5 function increases resistance against the root-knot nematode Meloidogyne javanica and suggests a potential role for the 1-IG modification pathway in Arabidopsis belowground defense.