Abstract: The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) is the key enzyme in the pathway for isoprenoid biosynthesis in plants. In this paper, a new HMGR gene, TmiHMGR, was first isolated from the leaves of Tilia miqueliana Maxim by rapid amplification of cDNA end technique. The full length cDNA of TmiHMGR was 2 160 bp, with a 1 758 bp open reading frame encoding a peptide of 585 amino acid residues. The deduced protein TmiHMGR has a calculated molecular weight of 62.9 kD and a pI value of 6.11. Phylogenetic tree analysis indicated that TmiHMGR had the closest relationship with HMGR from Malusx domestica. Tissue expression analysis revealed that TmiHMGR was strongly expressed in stems, while weakly in roots and leaves. The functional color complementation assay indicated that TmiHMGR could accelerate the biosynthesis of carotenoids in the Escherichia coli transformation, suggesting that TmiHMGR plays an influential role in isoprenoid biosynthesis.

Key words: Tilia miqueliana Maxim, 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), gene cloning, functional identification