Enhancing Taxol Biosynthesis by Overexpressing a 9-Cis-Epoxycarotenoid Dioxygenase Gene in Transgenic Cell Lines of Taxus chinensis

Plant secondary metabolites constitute are a wide range of compounds whose biosynthesis takes place in response to biotic and abiotic stresses. The phytohormone abscisic acid (ABA) acts as an important signaling molecule that regulates plant response to various stresses. Moreover, 9-cis-epoxycarotenoid dioxygenase (NCED) is one of the key enzymes in the ABA biosynthesis pathway in higher plants. In this study, a new NCED gene from Taxus chinensis, the TcNCED1, was overexpressed in transgenic T. chinensis cells, resulting in a maximum of 48 % more accumulation of ABA and a 2.7-fold increase of taxol production compared to the untransformed cells, respectively. These results indicate that overexpression of TcNCED1 can significantly increase the ABA and taxol level in T. chinensis cells, which probably provides an alternative approach in metabolic engineering to improve the yield of taxol in T. chinensis cells through genetic manipulation of the related genes in the ABA biosynthetic pathway.