Molecular evolution of flavonoid dioxygenases in the family Apiaceae

• Published in: Phytochemistry (Oxford) 2005-06, Vol.66 (11), p.1273-1284
• Main Authors: Gebhardt, Yvonne, Witte, Simone, Forkmann, Gert, Lukačin, Richard, Matern, Ulrich, Martens, Stefan
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Apiaceae; Apiaceae - enzymology; Apiaceae - genetics; Dioxygenases - genetics; Dioxygenases - metabolism; Evolution; Evolution, Molecular; Flavanone 3β-hydroxylase; Flavone synthase I; Flavonoid 2-oxoglutarate dependent dioxygenases; Flavonoids - chemistry; Flavonoids - metabolism; Gene Expression; Genes, Plant; Models, Chemical; Phylogeny; Plant Proteins - metabolism
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2005.03.030

Six 2-oxoglutarate dependent dioxygenases were cloned from Apiaceae species and characterized by heterologous expression in yeast. The novel sequences encoding flavone synthase I or flavanone 3β-hydroxylase were subjected to evolutionary analysis, and the evolution of the synthase from the hydroxylase is proposed. The synthase genes of Petroselinum and Daucus include introns which are lacking from the hydroxylase genes. Plant species of the family Apiaceae are known to accumulate flavonoids mainly in the form of flavones and flavonols. Three 2-oxoglutarate-dependent dioxygenases, flavone synthase or flavanone 3 β-hydroxylase and flavonol synthase are involved in the biosynthesis of these secondary metabolites. The corresponding genes were cloned recently from parsley ( Petroselinum crispum) leaves. Flavone synthase I appears to be confined to the Apiaceae, and the unique occurrence as well as its high sequence similarity to flavanone 3β-hydroxylase laid the basis for evolutionary studies. In order to examine the relationship of these two enzymes throughout the Apiaceae, RT-PCR based cloning and functional identification of flavone synthases I or flavanone 3β-hydroxylases were accomplished from Ammi majus, Anethum graveolens, Apium graveolens, Pimpinella anisum, Conium maculatum and Daucus carota, yielding three additional synthase and three additional hydroxylase cDNAs. Molecular and phylogenetic analyses of these sequences were compatible with the phylogeny based on morphological characteristics and suggested that flavone synthase I most likely resulted from gene duplication of flavanone 3β-hydroxylase, and functional diversification at some point during the development of the apiaceae subfamilies. Furthermore, the genomic sequences from Petroselinum crispum and Daucus carota revealed two introns in each of the synthases and a lack of introns in the hydroxylases. These results might be explained by intron losses from the hydroxylases occurring at a later stage of evolution.