Spatiotemporal Genetic Structure Of Wild Populations In Metasequoia Glyptostroboides And Implications For Germplasm Resources Conservation

Conservation of endangered species is playing a critic role in the maintenance of biodiversity.Metasequoia glyptostroboides is a seriously endangered endemic plant in China with an extremely narrow natural distribution range only covering a small area near the boundaries among Hubei,Hunan and Chongqing provinces.In recent decades,M.glyptostroboides had been widely planted,but the level of genetic diversity in those planted populations was far lower than that in wild populations.Therefore,in order to protect the germplasm resources of M.glyptostroboides,it is necessary to reveal the spatiotemporal genetic structure and develop effective sampling strategy of germplasm resources.Here,we carried out a complete sampling of M.glyptostroboides in five administrative villages in Lichuan county,Hubei,an area in the east of its natural range,and designed conservation strategy of germplasm resources based on spatiotemporal genetic structure of samples using 8 SSR loci.All populations showed a high level of genetic diversity with weak inter-population genetic differentiations.All sampled individuals of M.glyptostroboides were assigned into three genetic clusters with individuals belonging to each cluster being grouped in a few patches that were spatially discontinuous,showing significant spatial genetic structure.Further,limited gene flow was detected among patches,while extensive gene dispersal was present within each patch.The airborne pollens and seeds of M.glyptostroboides in relatively closed environments were likely to cause the limited gene dispersal.In addition,different cohorts of M.glyptostroboides divided by diameter at breast heights displayed similar spatial genetic patterns,indicating homogenous temporal genetic structure,probably because of the low intensity of anthropologic activities and the conservation efforts in the study area.Our results suggested that germplasm resources should be collected separately in the three genetic clusters,and seed collection could be absolutely randomly in all clusters.