Aureusidin Synthase: A Polyphenol Oxidase Homolog Responsible for Flower Coloration

Abstract

Aurones are plant flavonoids that provide yellow color to the flowers of some popular ornamental plants, such as snapdragon and cosmos. In this study, we have identified an enzyme responsible for the synthesis of aurone from chalcones in the yellow snapdragon flower. The enzyme (aureusidin synthase) is a 39-kilodalton, copper-containing glycoprotein catalyzing the hydroxylation and/or oxidative cyclization of the precursor chalcones, 2',4',6',4-tetrahydroxychalcone and 2',4',6',3,4-pentahydroxychalcone. The complementary DNA encoding aureusidin synthase is expressed in the petals of aurone-containing varieties. DNA sequence analysis revealed that aureusidin synthase belongs to the plant polyphenol oxidase family, providing an unequivocal example of the function of the polyphenol oxidase homolog in plants, i.e., flower coloration.

Proteins involved in biotic and abiotic stress responses as the most significant biomarkers in the ripening of Pinot Noir skins

“…PPOs, generally highly expressed in young developing tissues, constitute a large class of enzymes that catalyze the formation of o-quinones through the O 2 -dependent oxidation of monophenols and o-diphenols (Mayer and Harel 1991). It was proposed that in addition to their involvement in browning reactions as a consequence of pathogen infection, wounding and organ senescence, they may participate in other activities such as proanthocyanidin (Dixon et al 2004) and aurone (Nakayama et al 2000) biosynthesis. PPOs are synthesized in grape as a 67 kDa precursor that is then processed to remove a 10.6 chloroplast transit peptide from the N-terminus and a 16.2 kDa peptide of unknown function from the C-terminus with the resulting 40.5 kDa that is considered as the chloroplast catalytic unit (Dry and Robinson 1994).…”

Transforming the Snapdragon Aurone Biosynthetic Genes into Petunia Alters Coloration Patterns in Transgenic Flowers

“…In yellowflowering plants such as snapdragon, THC is converted into THC 4'-O-glucoside by UDP-glucose: chalcone 4'-O-glucosyltransferase (4'CGT), and THC 4'-O-glucoside is further converted into aureusidin 6-O-glucoside (yellow pigment) by aureusidin synthase (AS) [11]. In addition, in vitro activity of AS, catalyzing THC into aureusidin (yellow pigment), has also been reported [10]. Both genes, designated as AmAS1 and Am4'CGT, have been cloned from yellow snapdragon (A. majus cv.…”

“…Among these groups, anthocyanins, flavonols, chalcones and aurones contribute color to plants. Aurones are the bright yellow pigments found in some ornamental flowers such as snapdragon (Antirrhinum majus), cosmos and coreopsis [10]. Biochemical and flavonoid mutant studies from A. majus clearly revealed that aurones were produced from chalcones [4] [10].…”

“…Aurones are the bright yellow pigments found in some ornamental flowers such as snapdragon (Antirrhinum majus), cosmos and coreopsis [10]. Biochemical and flavonoid mutant studies from A. majus clearly revealed that aurones were produced from chalcones [4] [10]. The first common flavonoid compound is 2',4',6',4-tetrahydroxychalcone (THC) or also known as naringenin chalcone, which is the catalytic product of the key enzyme chalcone synthase (CHS).…”

In vitro inhibition of pigmentation and fiber development in colored cotton

“…However, the mechanism of its regulation is yet not well explored. Flavonoid biosynthesis is affected by many factors such as carbohydrates (He et al, 2005;Hua et al 2007;Huang et al, 2012), phytohormones (Russell and Galston, 1969;Weiss et al, 1990;Solfanelli et al, 2006), cytochrome c oxidase (COX) (Doostdar et al, 1995;de Vetten et al, 1999;Kitada et al, 2001), and polyphenol oxidase (PPO) (Nakayama et al, 2000). The deactivation of an isolated gene encoded for cytochrome b5 in Petunia could change the color of the flower (de Vetten et al, 1999).…”