Objective Michelia genus contains important landscaping and timber plants and mainly distributes in South China, however, the genetic relationship among different species is still unclear. Developing efficient genotyping methods and performing genetic relationship researches can provide theoretical and technical support for the utilization and protection of Michelia species.

Method Using 11 Michelia species as research materials, highly polymorphic SSR primers were screened out. M13-tailed fluorescent label method was used perform the PCR to obtain genotyping data and the genetic diversity parameters were calculated. Furthermore, a Neighbor-Joining(NJ)tree was constructed based on the genetic distance of each species.

Result All 12 pairs of SSR primers have relatively high polymorphism, and the amplification rate is 90.9%, which can finish genetic typing efficiently. The mean allele number for 12 markers is 8.17 and mean Shannon diversity index(I) is 1.836. The observed heterozygosity(Ho), expected heterozygosity(He)and polymorphic information content(PIC)are 0.365, 0.839 and 0.796, respectively. The cluster analysis results show that species belonging to different subgenus can be clearly distinguished on the NJ evolutionary tree. Among them, seven Subgen. Metamichelia species are clustered on two main divisions, and three species of Subgen. Michelia was clustered on the third branch. The result of genetic relationship analysis in this study is consistent with that of the previous taxonomic study.

Conclusion SSR marker genotyping system developed in this research can perform the genotyping of 11 Michelia species successfully. In the future, these markers can play an important role in hybrid parent evaluation, parent selection and hybrid offspring genetic relationship identification and other genetic studies.