Abstract: In order to study the regulation mechanism of chlorocholine chloride（CCC）on the biosynthesis of terpene trilactones，effects of CCC on photosynthesis，the contents of photosynthetic pigment，soluble sugar and terpene trilactones，and the expression level of key genes involved in ginkgolide biosynthesis in Ginkgo biloba leaves were investigated. The three-year-old ginkgo seedlings were foliar sprayed with 0（control），0.5，1.0 and 2.0 g · L-1 CCC. The results showed that 0.5，1.0，and 2.0 g · L-1 CCC treatments significantly enhanced the net photosynthetic rate，stomatal conductance，intercellular CO2 concentration，transpiration rate，and the contents of chlorophyll，carotenoids and soluble sugar in ginkgo leaves. The contents of ginkgolide A，B and bilobalide in ginkgo leaves treated with 1.0 and 2.0 g · L-1 CCC were significantly higher than those of control. The results of qRT-PCR analysis indicated that the expression levels of four key genes involved in terpene trilactones biosynthesis，namely DXS，DXR，GGPPS and LPS，were all markedly up-regulated by CCC treatment，indicating that CCC promoted terpene trilactones accumulation by inducing the expression of key genes related with ginkgolide biosynthesis.

Key words: Ginkgo biloba, chlorocholine chloride, photosynthesis, soluble sugar, terpene trilactone, key gene