Characterization of Anthocyanidin Synthase (ANS) Gene and anthocyanidin in rare medicinal plant-Saussurea medusa

Anthocyanidin synthase (ANS, leucoanthocyanidin oxygenase), a 2-oxoglutarate iron-dependent oxygenase, catalyzes the penultimate step in the biosynthesis of the anthocyanin class of flavonoids, from the colorless leucoanthocyanidins to the colored anthocyanidins. Here, we report the cloning and characterization of an anthocyanidin Synthase gene (SmANS1) from a cDNA library derived from a red callus line of Saussurea medusa, a traditional Chinese medicinal plant. SmANS1 exhibits significant similarities in amino acid sequence with members of a family of 2-oxoglutarate-dependent oxygenases. The deduced SmANS1 protein shared 83% and 79% identity with that of Callistephus chinensis and Gerbera hybrids, respectively. Reverse transcription-PCR (RT-PCR) analyses of SmANS1 transcripts showed that the SmANS1 was abundantly expressed in the cell cultures of red cell line and seedlings, and weakly expressed in the counterparts of yellow cell line, but was not expressed in the roots. Further more, the anthocyanins composition of cell cultures from Saussurea medusa was investigated using high-performance liquid chromatography/mass spectrometry (HPLC-ESI-MS) and tandem mass spectrometry (MS-MS). Major anthocyanins were identified as 3-O-glucosides cyanidin derivatives and minor peaks were identified as pelargonidin derivatives.