Abstract: 1-Hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate synthase (HDS) catalyses 2C-methyl-D-erythritol-2,4-cyclodiphosphate into 1-hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate in the penultimate step of 2C-methyl-D-erythritol 4-phosphate (MEP) pathway, which is an alternative plant terpenoids biosynthetic route that has been recently discovered. Homologous HDS cDNA (EuHDS) was isolated from leaves of Eucommia ulmoides by the methods of reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) technique. The full-length cDNA of EuHDS was 2 786 bp and encoded 743 amino acids with a predicted molecular mass of 82.25 kD, and a theoretical isoelectric point of 5.89. Two conserved motifs and three absolutely conserved cysteines (residues 644, 647 and 678) were discovered in the deduced coding sequence. Phylogenetic analysis revealed that EuDXR was more similar to Vitis vinifera(evolutionary distance, 0.049) than that of other species, followed by Solanum lycopersicum(0.052) and Hevea brasiliensis(0.052).

Key words: Eucommia ulmoides, HDS, gene, sequence analysis