Abstract: By using inter-simple sequence repeat (ISSR) markers technique, this paper studied the genetic diversity and variation of ten populations of Cercidiphyllum japonicum. The results showed that at species level, the percentage of polymorphic loci (P) was 69.59%, Shannon’s index (I) was 0.351 4 and Nei’s gene diversity (H) was 0.231 3, indicating a high level of genetic diversity. Whereas, at population level, they were only 30.61%, 0.173 3 and 0.115 6, respectively, suggesting a low level of genetic diversity. Genetic variation analysis showed that the coefficient of gene differentiation is 0.500 3 and the gene flow is 0.527 3 among populations, demonstrating a relatively high level genetic variation among the populations. Cluster analysis showed that there was no significant correlation between genetic distance and geographic distance. The high genetic variance among populations and the low genetic diversity within population could be attributed to the habitat fragmentation and the limited gene flow among populations.

Key words: Endangered species, Cercidiphyllum japonicum, genetic diversity, genetic variation, ISSR