Molecular cloning and functional analysis of a flavanone 3-hydroxylase gene from blueberry

ABSTRACTVaccinium corymbosum (blueberry) is touted as a superfood with numerous health benefits due to its high levels of flavonoids. Flavanone 3-hydroxylase (F3H) is a key regulatory enzyme of the flavonoid pathway. In this study, we cloned the full-length cDNA of F3H (designated VcF3H) from young blueberry leaves using rapid amplification of cDNA ends (RACE). The cDNA contained a 1080-bp open reading frame that encoded a 359-amino acid protein. The deduced VcF3H protein showed high similarities to other plant F3Hs. Conserved amino acid motifs required for ferrous iron binding (HXD) and 2-oxoglutarate binding (RXS) were identified in VcF3H, VcFLS (flavonol synthase), and VcANS (anthocyanidin synthase). Quantitative RT-PCR analysis demonstrated that VcF3H was expressed in all tissues tested, with particularly high expression in young leaves, fruits (pink and blue), and stems. Anthocyanins accumulated mainly in fruits, whereas flavonols were found mainly in leaves and stems. Furthermore, the expression pat...