Clonal Structure And Patterns Of Genetic Diversity In Dysosma Pleiantha (Berberidaceae), A Rare Endemic From Southeast China

Dysosma pleiantha, an important threatened medicinal plant (TMP) species, is restricted in distribution to the southeastern China. The species is capable of reproducing both sexually and asexually. The aim of this study was to evaluate the importance of sexual versus clonal recruitment, and investigate the levels and distribution of genetic variability in D. pleiantha.Inter-simple sequence repeat (ISSR) marker data were obtained and analysed with respect to spatial genet structure at a microscale level, genetic variation, and genetic structure.Clonal diversity in three small plots for D. pleiantha is high (G/N =0.351, Simpson's D = 0.734 ,on average). The ramets sharing the same genotype show a clumped distribution. Across all populations surveyed, average within-population diversity was remarkably low (e.g., 0.112 for Nei's gene diversity), with populations from the nature reserves maintaining relatively high amounts of genetic diversity. Among all populations, high genetic differentiation(AMOVA:Φ_ST= 0.4999; Nei's genetic diversity: G_ST = 0.4652, Bayesian analysis:Φ_B = 0.4361) was detected, together with an isolation-by-distance pattern.The sexual recruitment is a very important mechanism of regeneration in D. pleiantha populations. Low seedling recruitment due to inbreeding, restricted gene flow, and genetic drift are proposed to be the determinant factors responsible for the low genetic diversity and high genetic differentiation observed.The observed genetic differentiation among D. pleiantha populations is so great, management for the conservation of genetic variability in this species should not only aim to preserve large populations but also as many of the small populations outside natural reserves as possible. Furthermore, policy plans should be developed to stimulate recruitment in the small populations.Tissue culture technique is an effective means for recovery of D. pleiantha. Artificially propagated plants recruited from local plant sources are more likely to exhibit increased fitness over non-local genotypes in particular environments. Consequently, care should be taken to keep separate seedlings from different populations and reintroduce seedlings only into their original parental localities.