Genetic Control and Evolution of Anthocyanin Methylation  

Abstract

Anthocyanins are a chemically diverse class of secondary metabolites that color most flowers and fruits. They consist of three aromatic rings that can be substituted with hydroxyl, sugar, acyl, and methyl groups in a variety of patterns depending on the plant species. To understand how such chemical diversity evolved, we isolated and characterized METHYLATION AT THREE2 (MT2) and the two METHYLATION AT FIVE (MF) loci from Petunia spp., which direct anthocyanin methylation in petals. The proteins encoded by MT2 and the duplicated MF1 and MF2 genes and a putative grape (Vitis vinifera) homolog Anthocyanin O-Methyltransferase1 (VvAOMT1) are highly similar to and apparently evolved from caffeoyl-Coenzyme A O-methyltransferases by relatively small alterations in the active site. Transgenic experiments showed that the Petunia spp. and grape enzymes have remarkably different substrate specificities, which explains part of the structural anthocyanin diversity in both species. Most strikingly, VvAOMT1 expression resulted in the accumulation of novel anthocyanins that are normally not found in Petunia spp., revealing how alterations in the last reaction can reshuffle the pathway and affect (normally) preceding decoration steps in an unanticipated way. Our data show how variations in gene expression patterns, loss-of-function mutations, and alterations in substrate specificities all contributed to the anthocyanins' structural diversity.

Flower color modification in <i>Rosa hybrida</i> by expressing the <i>S</i>-adenosylmethionine: anthocyanin 3′,5′-<i>O</i>-methyltransferase gene from <i>Torenia hybrida</i>

“…(Figure 1), the major anthocyanin in the torenia petals (Nakamura et al 2010), the activity of the torenia A3′5′OMT with delphinidin 3-glucoside 5-coumaroylglucoside could not be determined because of its unavailability. Petunia and tomato A3′5′OMT catalyze the methylation of delphinidin 3-coumaroylrutinoside 5-glucoside (Provenzano et al 2014;Roldan et al 2014).…”

“…The torenia AOMT homolog (clone TMT5, the nucleotide sequence is registered as LC005089 in DDBJ/ENA/GenBank databases) was obtained from a torenia petal cDNA library by screening with DIGlabeled petunia AOMT MT2cDNA (Provenzano et al 2014). The open reading frame of the AOMT homolog comprised 239 amino acid residues.…”

“…Genetic and biochemical analyses of Petunia hybrida, a model species used to study flower color and anthocyanin biosynthesis, have suggested that petunia has two pairs of A3′5′OMT and A3′OMT loci: METHYLATION AT THREE (MT1 and MT2) and METHYLATION AT FIVE (MF1 and MF2) (Wiering 1974;Wiering and de Vlaming 1977). Recently, it was shown that the A3′OMT gene is encoded by MT2, the A3′5′OMT genes are encoded by MF1 and MF2, and MT1 is nonexistent (Provenzano et al 2014). A grape A3′5′OMT gene was isolated and the recombinant grape A3′5′OMT in in vitro assays was shown to catalyze the 3′-or 3′,5′-methylation of cyanidin 3-glucoside, delphinidin 3-glucoside, quercetin 3-glucoside, cyanidin, quercetin, and myricetin; however, pelargonidin 3-glucoside, catechin, and epicatechin were not suitable substrates (Hugueney et al 2009;Lucker et al 2010).…”

“…Tomato A3′5′OMT catalyzes the methylation of quercetin, myricetin, quercetin 3-glucoside, quercetin 3-rutinoside, delphinidin 3-glucoside, and cyanidin 3-glucoside, and its strong preference for delphinidin 3-glucoside was demonstrated (Roldan et al 2014). These AOMTs are closely related to the caffeoyl CoA OMT (CCoOMT) clade (Group A1) in the plant OMT family (Lam et al 2007;Provenzano et al 2014) in terms of their amino acid sequences and they are designated as CCoOMT-like proteins, together with Arabidopsis spermidine methyltransferase (Fellenberg et al 2008) and an ice plant OMT, which has a broad substrate specificity (Ibdah et al 2003).…”

ANALISIS PROKSIMAT, SENYAWA FENOLIK, SIFAT ANTIOKSIDAN DAN ANTIBAKTERI KULIT BUAH Lepisanthes alata

“…Jambu yang dikeringbekukan (freeze dried) mengalami perubahan warna yang minimal, akan tetapi pepaya akan berubah menjadi lebih pucat dengan teknik yang sama (Hawlader, 2006). Perubahan kadar polifenol, termasuk didalamnya pigmen warna, dalam pengolahan pasca panen dapat dipengaruhi oleh glikosilasi, asetilasi, dan metilasi pigmen (Provenzano et al, 2014). Polifenol oksidase (PPO) memiliki peran terbatas dalam menurunkan kadar antosianin oleh sebab gugus glikosida yang dimilikinya (Madrau et al, 2009).…”