Genetic structure and gene flow in the endangered aquatic economic crop Brasenia schreberi J. F. Gmel. (Nymphaeaceae) in China

摘要

Inter-simple sequence repeat (ISSR) markers were used to measure the levels of genetic variation and patterns of population structure within and among five extant populations of Brasenia schreberi, an endangered aquatic plant in China. Six primers selected from sixty ISSR primers were used in the study which amplified 49 reproducible bands with 22 (44.9%) being polymorphic, indicating low levels of genetic diversity at the species level. AMOVA analysis revealed that most genetic variation (85.64%) is present among populations. The low level of gene flow (N_m = 0.1) is estimated among five remaining populations. A Mantel test show significant relationship between genetic distance and geographic distance (r = 0.91). Several factors including clonal growth, habitat fragment, population isolation, restricted gene flow among populations and agricultural practices, might have played an important role in maintaining the genetic structure of B. schreberi populations in China. In view of the limited genetic information currently available for B. schreberi, we recommend in situ preservation of the remaining population.