Abstract: In this study, gibberellin 20 oxidase gene was cloned from the stems of Camellia lipoensis Chang et Xu using RT-PCR and RACE methods. The full length of the GA20 oxidase gene, named ClGA20ox2, was 1 567 bp(GenBank accession No.KF823787), which contained a 1 146 bp open reading frame (ORF) encoding 382 amino acid residues, contained a 5′-UTR with 115 bp and 3′-UTR with 303 bp. The putative protein molecular weight was 43.56 kD and its theoretical isoelectric point was 7.02. The deduced amino acid sequence of the ClGA20ox2 protein shares 73% and 72% identities with those of Nerium indicum and Populus trichocarpa, respectively. The phylogenetic tree constructed on the basis of amino acid sequences suggested that the relationship of GA oxidase from C.lipoensis was most intimate with those from N.indicum and P.trichocarpa. The results from the analysis on tissue specific expression showed that the endogenous ClGA20ox2 gene expression levels in the root, stem, leaf and seed of C.lipoensis were different. The ClGA20ox2 transcripts were the most abundant in two-year old stem, followed by young leaf and root, and then mature leaf and seed, the lowest transcripts were found in apical shoot meristems.

Key words: Camellia lipoensis, GA20 oxidase, sequence analysis, cloning