Metabolomic characterization of the possible involvement of a Cytochrome P450, CYP81F4, in the biosynthesis of indolic glucosinolate in Arabidopsis

Abstract

We studied the biosynthetic role of a cytochrome P450, CYP81F4, in Arabidopsis. The CYP81F4 gene was found within a gene expression network containing the transcription factor gene MYB34/ATR1 involved in tryptophan metabolisms. Root metabolic profiles in null cyp81f4 mutant lines were analyzed using an in-house metabolomics scheme based on Fourier transform ion cyclotron resonance mass spectrometry. The cyp81f4 mutant plants exhibited a build-up of indole-3-yl-methyl glucosinolate with concomitant loss of 1-methoxy-indole-3-yl-methyl glucosinolate. A pathway prediction supported by a detailed glucosinolate analysis indicated that CYP81F4, together with an unidentified methyltransferase, is involved in the formation of the methoxy group in the indole ring to yield 1-methoxy-indole-3-yl-methyl glucosinolate in Arabidopsis roots. Current results suggest that 1-methoxy-indole-3-yl-methyl glucosinolate is produced by the activity of CYP81F4 in Arabidopsis roots.