Abstract:

Adiantum reniforme var. sinense is an economically important plant species endemic to China. It is only found in a few regions of the Chongqing Municipal Region. For decades, its distribution has been shrinking as a result of over-exploitation, which has caused endangerment of this species. To assist in efforts to effectively conserve this species, we investigated the genetic variation of six natural populations using isoelectric focusing in thin-layer polyacrylamide slab gels. Fourteen loci of five enzyme systems were detected, of which seven were polymorphic. The mean number of effective alleles per locus (A_e) = 1.778, the percentage of polymorphic loci (P) = 0.441, the mean expected heterozygosity (H_e)= 0.199， and the mean observed heterozygosity (H_o)= 0.235. The results revealed that low levels of genetic diversity existed within the natural populations of A. reniforme var. sinense in comparison with other species of ferns. Only 1.49% of the genetic variation occurred among populations whereas 98.51% existed within populations, suggesting a very low genetic divergence among the populations. The equilibrium state of the populations was measured using Hardy-Weinberg equilibrium and the Fixation Index (F). The results showed that a mixed mating system was possibly the main heterogamy of this species, and its endangerment was caused by overexploitation and habitat loss.