Abstract:

Metasequoia glyptostroboides, a “living fossil” plant endemic to China, has been cultivated for more than fifty years. In order to evaluate to what extent the cultivated populations have conserved the genetic variation of the wild ones, we estimated the allozymic variation and genetic diversity in eight cultivated populations using isoelectric focusing in thin-layer polyacrylamide slab gels. Twenty-three loci of nine enzyme systems were detected and used for estimating population genetic diversity. Obvious difference in allele frequency was observed in eight of 23 loci, and rare alleles were detected in two populations. Genetic variability of cultivated M. glyptostroboides was low (PPL = 33.15%, A = 1.375, H_e = 0.161), and the genetic diversity was lower in cultivated populations than in relict ones, indicating that genetic diversity of cultivated populations could not completely cover that of relict M. glyptostroboides. Based on the allozymic variation data, a UPGMA dendrogram was constructed, comprising nine individuals of Metasequoia glyptostroboides var.caespitosa from Qianjiang of Hubei Province and nine individuals from each of three M. glyptostroboides populations, i.e., Qianjiang, Wuhan and Shanghai. Moreover, the genetic relationships among the population of M. glyptostroboides var. caespitosa and eight populations of M. glyptostroboides were analyzed. These analysis suggested that Metasequoia glyptostroboides var. should not be treated as a variety of M. glyptostroboides.