Molecular cloning and characterization of flavonol synthase in Acacia confusa

Flavonoids are abundant in the leaves, flowers, branches, bark, and heartwood of Acacia confusa Merr. (Leguminosae), and the extracts have been found to have strong antioxidant activities. Flavonols are the major class of flavonoids found in A. confusa. The full-length gene (designated as AcFLS) contains an open reading frame of 996 nucleotides encoding 331 amino acid residues with a predicted molecular weight of 38 kDa and pI of 5.7. AcFLS mRNAs were abundant in the seedlings leaves and the flowers. Wounding by cutting leaves induced maximum AcFLS mRNA accumulation 6-12 h after treatment. AcFLS could enzymatically transform dihydromyricetin, dihydroquercetin, and naringenin into the flavonols myricetin, quercetin, and kaempferol, respectively. AcFLS could bind these three substrates with similar affinity.