Biodiv Sci ›› 2013, Vol. 21 ›› Issue (6): 723-731.DOI: 10.3724/SP.J.1003.2013.09117

• Orginal Article • Previous Articles     Next Articles

Genetic diversity and population structure of Bretschneidera sinensis, an endangered species

Gangbiao Xu1,*(), Yan Liang1, Yan Jiang2, Xiongsheng Liu1, Shangli Hu1, Yufei Xiao1, Bobo Hao1   

  1. 1 Laboratory of Forest Genetics, Central South University of Forestry and Technology, Changsha 410004
    2 Guangxi Forestry Research Institute, Nanning 530001
  • Received:2013-05-13 Accepted:2013-09-10 Online:2013-11-20 Published:2013-12-02
  • Contact: Xu Gangbiao

Abstract:

Amounts and distribution of intraspecific genetic variation provide benchmarks for developing conservation strategies. Bretschneidera sinensis is a monotypic relic species listed in the First Grade of the List of Wild Plants Under State Protection (First Batch) in China. We examined the genetic diversity and genetic structure of 219 B. sinensis individuals sampled from 15 natural populations distributed in Hunan, Jiangxi, Guangdong, Guangxi, and Guizhou using inter-simple sequence repeat (ISSR) markers generated by seven ISSR primers. The percentage of polymorphic bands (PPB) at the species and population level was 74.42% and 38.06%, respectively. Shannon’s index (I) of phenotypic diversity at the species and population level was 0.3630 and 0.2081, respectively, and Nei’s genetic diversity (He) at the species and population level was 0.2397 and 0.1405, respectively. These results indicate that B. sinensis contains relatively high levels of genetic diversity. Analysis of molecular variance (AMOVA) and estimates of the coefficient of genetic differentiation based on phenotypic diversity index also indicated high levels of population subdivision (GST = 0.2973; FST = 0.4267) in the species. Analysis of the ISSR data using UPGMA further revealed that populations were genetically clustered into two groups, while a Mantel test showed that genetic divergence was significantly correlated with geographical distance among populations (Mantel test; r = 0.3096, P = 0.008). We conclude from our results that B. sinensis is not endangered due to low evolutionary potential stemming from low genetic diversity, but by habitat destruction coupled with a low reproductive capacity, poor adaptability and weak competitiveness. The Mt. Yangming, Mt. Mangshan, Ruyang, and Mt. Bamianshan populations of the species with higher genetic diversity should be given priority for conservation, and inbreeding depression monitoring should be conducted.

Key words: Bretschneidera sinensis, ISSR markers, population genetic structure, endangered mechanism