ISSR Analysis on Genetic Diversity of Medically Important Lycium ruthenicum Murr. in Xinjiang

Lycium ruthenicum(Solanaceae)is an important medicinal plant mainly distributed in Northwestern China.In recent years,however,the distribution range of this species has been reduced greatly due to human overexploitation and deterioration of its habitat.Studying the population genetics of this species is essential for the conservation and sustainable utilization of the plant germplasm resource.In this study,we used seven ISSR markers to measure genetic diversity of 115individuals from eight natural populations of L.ruthenicumin Xinjiang(six populations)and Gansu(two populations).A total of 64DNA fragments were scored,and 78.1%of polymorphic loci(PPL)found.High level of genetic diversity was detected in L.ruthenicum(H=0.29;Ⅰ=0.43).AMOVA analysis indicated that most variance(77.0%)resided within populations,with only a small proportion of total variation residing between populations(23%,FST=0.23).Results of the Mantel test(r=0.3602,p=0.910)and UPGMA cluster of the Xinjiang populations indicated that there was no significant relationship between geographical distance and genetic distance.UPGMA cluster of all sampled individuals showed that individuals from each population did not cluster together.The probable causes that have contributed to the current pattern of genetic structure were discussed and suggestions on future protection of the L.ruthenicumfrom southern Xinjiang were also given.