Abstract:

Bretschneidera sinensis, an endemic plant species native to China, is in peril of extinction because of scarce natural genetic resources and human destruction of its natural habitat. In order to assess the genetic integrity of the ex situ conservation populations of this species, the genetic diversity of four natural and two planted populations from Nanling Mountains was investigated using inter-simple sequence repeat (ISSR) markers. A total of 86 discernible DNA fragments were detected with 7 primers, and the 62 fragments were polymorphic. The percentage of polymorphic loci (PPB) and Shannon's phenotypic diversity index(H_POP) in a population ranged from 36.05% to 53.49%, and from 0.204 0 to 0.307 9, respectively. The population genetic indexes of natural populations(PPB=70.93%,H_POP=0.388 2) were higher than those of planted populations (PPB=53.49%, H_POP=0.294 1). Analysis of molecular variance (AMOVA) revealed that there was significant genetic difference among and within populations, and the genetic differences (Φ_ST=0.340 7) among natural populations were obviously higher than those of planted populations (Φ_ST=0.224 8). This result indicated high level genetic diversity at both population and species level of B. sinensis. The planted populations for ex situ conservation could not effectively protect the genetic diversity of this species from Nanling region. The planting material collection strategies for ex situ conservation should include as many as possible different populations.

Key words: Bretschneidera sinensis, genetic diversity, ISSR, natural population, planted population