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Opisthopappus Shih is endemic to the Taihang Mountains, China. It grows in the crevice of cliffs and is in fragmented distribution. This genus consists of two species, namely, O. taihangensis (Ling) Shih and O. longilobus Shih, which are both endangered plants in China. This study adopted intersimple sequence repeat markers (ISSR) to analyze the genetic diversity and genetic structure from different levels (genus, species, and population) in this genus. A total of 253 loci were obtained from 27 primers, 230 of which were polymorphic loci with a proportion of polymorphic bands (PPB) of up to 90.91% at genus level. At species level, both O. taihangensis (PPB = 90.12%, H = 0.1842, and I = 0.289) and O. longilobus (PPB = 95.21%, H = 0.2226, and I = 0.3542) have high genetic diversity. Their respective genetic variation mostly existed within the population. And genetic variation in O. longilobus (84.95%) was higher than that in O. taihangensis (80.45%). A certain genetic differentiation among populations in O. taihangensis was found (G st = 0.2740, Φst = 0.196) and genetic differentiation in O. longilobus was very small (G st = 0.1034, Φst = 0.151). Gene flow in different degrees (N m = 1.325 and 4.336, resp.) and mating system can form the existing genetic structures of these two species. Furthermore, genetic differentiation coefficient (G st = 0.0453) between species and the clustering result based on the genetic distance showed that interspecific differentiation between O. taihangensis and O. longilobus was not significant and could occur lately.

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ABSTRACT. Comprehensive research of genetic variation is crucial in designing conservation strategies for endangered and threatened species. Sinowilsonia henryi Hemsi. is a tertiary relic with a limited geographical distribution in the central and western areas of China. It is endangered because of climate change and habitat fragmentation over the last thousands of years. In this study, amplified fragment length polymorphism markers were utilized to estimate genetic diversity and genetic structure in and among S. henryi. In this study, Nei's genetic diversity and Shannon's information index were found to be 0.192 and 0.325 respectively, indicating a moderate-to-high genetic diversity in species. According to analysis of molecular variation results, 32% of the genetic variation was shown to be partitioned among populations, demonstrating a relatively high genetic divergence; this was supported by principal coordinate analysis and unweighted pair-group method with arithmetic average analysis. Moreover, 12341Genetic variation of S. henryi revealed by AFLP ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (4): 12340-12351 (2015) the Mantel test showed that there was no significant correlation between genetic and geographical distances. The above results can be explained by the effects of habitat fragmentation，history traits, and gene drift. Based on the results, several implications were indicated and suggestions proposed for preservation strategies for this species.