Isolation and characterization of eight polymorphic microsatellite loci from Ludwigia polycarpa (Onagraceae), a threaten herb in North America

Ludwigia polycarpa is the only species of section Microcarpium occurring north of 37°N in the central midwest of the United States. Recently, the loss of wetlands in North America reduced the population number and size of L. polycarpa dramatically. In this study, for the purpose of the conservation of the endangered species, we described eight microsatellite DNA loci. High variabilities enable these molecular markers to assess the population structure. The number of alleles per locus ranged from 8 to 23. The expected (H_E) and observed (H_O) heterozygosities ranged from 0.86 to 0.96 and 0.00 to 1.00, respectively. Seven of the eight microsatellite loci displayed significant departures from Hardy-Weinberg expectations, likely due to the loss of habitats and the small population size. No linkage disequilibrium was observed in the pairwise comparisons of loci. The application of these microsatellite loci in L. polycarpa may provide a tool for understanding its demography and population structure.