Abstract:Cytochrome P450 plays a very important role in the biosynthesis of plant phenylpropanes, alkaloids and terpenoids, etc. In order to learn more about the type and quantity of P450 in Pyrus bretschneideri Rehd, P450 genome has been screened and analyzed based on the amino acids and cDNA database of Pyrus bretschneideri Rehd. The evolutionary relationships, gene physical mapping, as well as secondary structural elements of P450 in whole-genome of Pyrus bretschneideri Rehd are analyzed. A total of 226 P450 genes are initially identified in Pyrus bretschneideri Rehd genome. The distribution of 226 genes on the chromosomes can be known by gene mapping analysis. Many chromosomes contain gene clusters except the chromosome 4,5,9. The relationship of gene structure and evolution are further identified according to the comparison of the gene structure and evolutionary tree. Analysis of the secondary structure showed the P450 protein sequence of Pyrus bretschneideri Rehd also has the characteristic domain of P450 protein. These findings establishes the foundation for further analysis of the function of P450 gene in Pyrus bretschneideri Rehd.