Abstract: 1-deoxy-D-xylulose-5-phosphate synthase（DXS）is the first key enzyme of the MEP terpenoids synthetic pathway,thus it plays an important role in the biosynthesis of plant terpenoid. In this study,the complete ORF of CsDXS1 gene was cloned from Camellia sinensis var. fudingdabaicha based on the previous tea plant transcriptome database,and it’s length was 2 154 bp encoding 717 amino acids. The bioinformatics analysis indicated that CsDXS1 gene belonged to the class I of DXS gene family. The deduced CsDXS1 protein shared high similarity（85%-90%）with other homologous protein,and it was an instable and hydrophilic protein with no signal peptide and transmembrane domain. There were 15 high-probability phosphorylation sites. Furthermore,CsDXS1 had two typical conserved domains of transketolase superfamily. The expression profiles of CsDXS1 gene in different tissues of tea plant or under hormonal treatments were detected using quantitative real-time PCR analysis. Results showed that CsDXS1 exhibited the highest expression in the third leaf,and higher expressions in the young leaves than in the steam and old leaves. The tissue expression profiles showed that the successive order as the third leaf > the fourth leaf > the first leaf > the second leaf > young stem > old stem >old leaf. The CsDXS1 gene expression were induced at varied degrees in response to six hormonal treatments,also the occurrence times of expression peak differed. The expressions of CsDXS1 gene was in the peak（4 h）under IAA and ABA treatments,which was 1.5 times of the control. CsDXS1 gene was at the lowest expression（24 h）under MeJA treatment,which was only 1.1 times of the control.

Key words: Camellia sinensis, DXS,terpenoids, sequence analysis, gene expression