High genetic diversity and low population differentiation of a medical plant Ficus hirta Vahl., uncovered by microsatellite loci: implications for conservation and breeding

BACKGROUND: Wuzhimaotao (Radix Fici Hirtae) originates from the dry root of Ficus hirta (Moraceae), which is widely known as a medical and edible plant distributed in South China. As the increasing demand for Wuzhimaotao, the wild F. hirta has been extremely reduced during the past years. It is urgent to protect and rationally develop the wild resources of F. hirta for its sustainable utilization. However, a lack of genetic background of F. hirta makes it difficult to plan conservation and breeding strategies for this medical plant. In the present study, a total of 414 accessions of F. hirta from 7 provinces in southern China were evaluated for the population genetics using 9 polymorphic SSR markers. RESULTS: A mean of 17.1 alleles per locus was observed. The expected heterozygosity (He) varied from 0.142 to 0.861 (mean = 0.706) in nine SSR loci. High genetic diversity (H(e) = 0.706, ranged from 0.613 to 0.755) and low genetic differentiation among populations (G’(ST) = 0.147) were revealed at population level. In addition, analysis of molecular variance (AMOVA) indicated that the principal molecular variance existed within populations (96.2%) was significantly higher than that among populations (3.8%). Meanwhile, the three kinds of clustering methods analysis (STRUCTURE, PCoA and UPGMA) suggested that the sampled populations were clustered into two main genetic groups (K = 2). Mantel test showed a significant correlation between geographic and genetic distance among populations (R(2) = 0.281, P < 0.001). Pollen flow, seed flow and/or geographical barriers might be the main factors that formed the current genetic patterns of F. hirta populations. CONCLUSIONS: This is a comprehensive study of genetic diversity and population structure of F. hirta in southern China. We revealed the high genetic diversity and low population differentiation in this medicinal plant and clarified the causes of its current genetic patterns. Our study will provide novel insights into the exploitation and conservation strategies for F. hirta.