Genetic diversity of natural populations of Machilus thunbergii, an endangered tree species in eastern China, determined with ISSR analysis.

The genetic diversity of 10 Machilus thunbergii populations in eastern China was analyzed using inter-simple sequence repeat markers. The populations showed high genetic diversity, with an overall population genetic diversity of 0.2343. Genetic diversity varied largely among populations, and populations with the highest genetic diversity were mainly from the eastern and western parts of the natural distribution area. Small populations, lack of effective gene flow, and fragmentation of habitats have led to greater genetic differentiation among populations, with 41.18% of genetic variation existing among populations. Unweighted pair-group method with arithmetic mean cluster analysis indicated that populations distributed between latitudes 25° and 31°N were clustered together and should be prioritized for in situ conservation. Northern, eastern, and southern populations were located in peripheral areas of the distribution range and were clustered separately. Collection of distinctive germplasm from peripheral populations should be promoted and ex situ conservation of elite germplasm should be implemented.