Abstract:

The genetic diversity of eighteen Platycladus orientalis provenances from seventeen provinces was analyzed by AFLP markers.Eight primers produced a total of 1 613 polymorphic bands(92.19%).The average effective number of alleles, Nei's gene diversity and Shannon's information index were 1.199 3, 0.123 9 and 0.194 9,respectively, indicating that there was plentiful genetic diversity among the provenances of P. orientalis. Genetic diversity of the middle provenances was less than that of provenances collected from the south and the north regions. Analysis of molecular variance(AMOVA)showed that variance component within provenances (74.86%)was higher than that among regions(11.12%) and among provenances within regions(14.02%).The distribution of discontinuity, geographical isolation and low levels of gene flow(N_m=1.437 2) between the provenances were major factors that led to genetic differentiation.Nei's (1972) genetic distance was applied to unweighted pair-group method with arithmetic means (UPGMA) cluster analysis,and the results showed that the similar latitude provenances were clustered together, and eighteen provenances were clustered into four groups(north,south,middle and Shandong provenances). A Mantel test confirmed that there was a positive correlation between the genetic distance and geographical distance.

Key words: Platycladus orientalis, provenances, AFLP, genetic diversity, genetic structure