Abstract
Anthocyanins, a class of flavonoids, are responsible for the orange to blue coloration of flowers and act as visual attractors to aid pollination and seed dispersal. Malonyl-CoA is the precursor for the formation of flavonoids and anthocyanins. Previous studies have suggested that malonyl-CoA is formed almost exclusively by acetyl-CoA carboxylase, which catalyzes the ATP-dependent formation of malonyl-CoA from acetyl-CoA and bicarbonate. In the present study, the full-length cDNA of Petunia hybrida acyl-activating enzyme 13 (PhAAE13), a member of clade VII of the AAE superfamily that encodes malonyl-CoA synthetase, was isolated. The expression of PhAAE13 was highest in corollas and was down-regulated by ethylene. Virus-induced gene silencing of petunia PhAAE13 significantly reduced anthocyanin accumulation, fatty acid content, and cuticular wax components content, and increased malonic acid content in flowers. The silencing of PhAAE3 and PhAAE14, the other two genes in clade VII of the AAE superfamily, did not change the anthocyanin content in petunia flowers. This study provides strong evidence indicating that PhAAE13, among clade VII of the AAE superfamily, is specifically involved in anthocyanin biosynthesis in petunia flowers.
Highlights
Flavonoids are secondary metabolites that are common to all higher plants
This study provides strong evidence indicating that Petunia hybrida acyl-activating enzyme 13 (PhAAE13), among clade VII of the AAE superfamily, is involved in anthocyanin biosynthesis in petunia flowers
Because flavonols often accumulate to high levels in flowers, providing protection from ultraviolet B (UV-B) light (Albert et al, 2009; Li et al, 1993; Ryan et al, 2002), the effects of UV-B on PhAAE13 expression were examined using Quantitative real-time PCR (qPCR)
Summary
Flavonoids are secondary metabolites that are common to all higher plants. This category of compounds includes anthocyanins, flavanones, flavones, and flavonols (Koes et al, 1994). Anthocyanin pigments provide flowers with bright red and blue colors, and are induced in vegetative tissues by various signals (Mol et al, 1996). The anthocyanin biosynthetic pathway likely represents one of the best-studied examples of higher plant secondary metabolism (Fig. 1) (Koes et al, 2005; Rausher et al, 1999). The genes encoding flavonoid enzymes have been isolated from a variety of plant species. Flavonoids are formed by adding three molecules of malonyl-CoA to a coumaroyl-CoA starter, which is catalyzed by chalcone synthase and forms naringenin chalcone (Halls and Yu, 2008)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
