Conservation Genetics Of Suriana Maritima(surianaceae) In China

Suriana maritima L., the sole species of Suriana(Surianaceae), grows as a perennial shrub or small tree on Paracel Islands with small numbers. The taxonomic status of S. maritima among angiosperms has been controversial. At different times, S. maritima has been placed in Phytolaccaceae, Simaroubaceae or Surianaceae, and these families were suggested to place in Rutales, Rosales or Fabales. In China, S. maritima has been found only on a few islands of the Paracel Islands, where only a few fragmented populations and individuals exist. Therefore, S. maritima is an interesting species for the phylogenetic study of the Surianaceae and Fabales, and is urgently needed for conservation. In this study, we used SSR markers and chloroplast DNA sequence variation to investigate the genetic variation and population genetic structure of S. maritima, hoping to provide scientific basis for conservation and restoration practices of this species. The main results are as follows:(1) Using Illumina Hi Seq TM 2000 sequencing technology, we developed 17 SSR primers, and using these primers to determine the genetic diversity of 54 individuals from six populations of S. maritima. The results showed that no variation was detected, either within or among the populations. The chloroplast DNA sequence variation of the trn L intron, psb B-psb F and trn L-trn F, were also used to assess the genetic diversity of S. maritima, and, no sequence variation was detected within or among the populations, either. Compared the psb B-psb F sequence to the psb B-psb F sequence(673bp) that obtained from Gen Bank of S. maritima from America, we found that the similarity of two sequences was 100% with no base difference. Compaired, the trn L intron sequence to the trn L intron sequence that obtained from Gen Bank of S. maritima from South Africa and found that the similarity of two sequences was 99.6% with only two bases difference(the genetic differentiation was only 0.4%). The results indicated an extremely low level of genetic variation of S. maritima in China, which may result from a single ancestor and selfing. And bottlenecks, founder effects, genetic drift and the cumulative effects of inbreeding in small populations also, may result in a further loss of genetic diversity of this species during its evolution process.(2) The results of the population genetics of S. maritima in this study will provide theoratical bases for conservation practices. We suggested that S. maritima is included in the Chinese Rare and Endangered Plants List. It is important to protect the populations and habitat of S. maritima in situ. However, the genetic diversity of S. maritima and its adaptability to environmental changes in the long run can‘t be increased by enlarging population size through artificial breeding. If individuals from populations with relatively higher level of genetic diversity or with different ancestors were introduced, analysis of genetic structure among S. maritima populations in the world is needed, and the genetic pollution risk must be taken into consideration.