The terpene trilactones (TTLs) are believed to be important for the pharmacological properties of Ginkgo biloba leaves extract. 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is a critical enzyme involved in the biosynthetic pathway of TTLs. In this study, an 1.2-kb fragment of 5' flanking region of the HMGR gene (GbHMGR), was isolated from G. biloba by genome walking. Extensive sequence analysis revealed the presence of evolutionarily conserved and over-represented putative cis-acting elements in light-regulated transcription, hormone signaling (gibberellic acid, jasmonare and salicyl...