title: Methylation mediated by an anthocyanin, O-methyltransferase, is involved in purple flower coloration in Paeonia.
abstract: Anthocyanins are major pigments in plants. Methylation plays a role in the diversity and stability of anthocyanins. However, the contribution of anthocyanin methylation to flower coloration is still unclear. We identified two homologous anthocyanin O-methyltransferase (AOMT) genes from purple-flowered (PsAOMT) and red-flowered (PtAOMT) Paeonia plants, and we performed functional analyses of the two genes in vitro and in vivo. The critical amino acids for AOMT catalytic activity were studied by site-directed mutagenesis. We showed that the recombinant proteins, PsAOMT and PtAOMT, had identical substrate preferences towards anthocyanins. The methylation activity of PsAOMT was 60 times higher than that of PtAOMT in vitro. Interestingly, this vast difference in catalytic activity appeared to result from a single amino acid residue substitution at position 87 (arginine to leucine). There were significant differences between the 35S::PsAOMT transgenic tobacco and control flowers in relation to their chromatic parameters, which further confirmed the function of PsAOMT in vivo. The expression levels of the two homologous AOMT genes were consistent with anthocyanin accumulation in petals. We conclude that AOMTs are responsible for the methylation of cyanidin glycosides in Paeonia plants and play an important role in purple coloration in Paeonia spp.
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Du
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Kui-Xian
authors.initials: KX
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Qing-Yin
authors.initials: QY
authors.lastname: Zeng
authors.affiliation: MOgene Green Chemicals, Saint Louis, MO 63132, USA.
authors.forename: Mohammad-Wadud
authors.initials: MW
authors.lastname: Bhuiya
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China University of Chinese Academy of Sciences, Beijing 100049, PR China.
authors.forename: Shang
authors.initials: S
authors.lastname: Su
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China wanglsh@ibcas.ac.cn shuqy@ibcas.ac.cn.
authors.forename: Qing-Yan
authors.initials: QY
authors.lastname: Shu
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Hong-Xu
authors.initials: HX
authors.lastname: Ren
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China.
authors.forename: Zheng-An
authors.initials: ZA
authors.lastname: Liu
authors.affiliation: Key Laboratory of Plant Resources/ Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China wanglsh@ibcas.ac.cn shuqy@ibcas.ac.cn.
authors.forename: Liang-Sheng
authors.initials: LS
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000235:genetics / Q000378:metabolism; D003116:Color; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D029596:Paeonia / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010858:Pigmentation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D010940:Plant Proteins; D008780:Methyltransferases
keywords: Anthocyanin O-methyltransferase; Paeonia; catalytic activity; flavonoids; flower coloration; single amino acid substitution.