Abstract: Ent-kaurene oxidase（KO）is a critical enzyme in the pathway of gibberellins biosynthesis. In this research，ent-kaurene oxidase gene in pear，designated as PpKO（GenBank accession number： HM003112），was isolated from‘Whangkeumbae’（Pyrus pyrifolia Nakai）stem apical tissue by homologous cloning and RACE technology. The full cDNA was 1 752 bp in length with an open reading frame（ORF）of 1 548 bp encoding a protein of 515 amino acids. Molecular weight and isoelectric point of the protein was 59.007 kD and 7.19，respectively. Amino acids homology analysis indicated that the sequence had 59.4%–95.9% similarity with those of other reported plants. Amino acids cluster analysis showed that KO from apple was clustered together with PpKO firstly，and followed by that from strawberry. Bioinformatics analysis exhibited that PpKO contained a core functional domain of cytochrome P450（FXXGXRXCXG）and transmembrane region near the N-terminus.

Key words: pear, ent-kaurene oxidase gene（PpKO）, bioinformatics analysis