Genetic Diversity Of Opisthopappus Shih (Compositae) Opulations Based On ISSR Analysis

Opisthopappus Shih is classified as subtribe Artemisiinae of Asteraceae who shouldbe closer to Dendranthema and Ajania. Opisthopappus Shih, which belongs to perennialherbs, contains two species: Opisthopapus taihangensis (Ling) Shih and Opisthopappuslongilobus Shih. These herbs spread in the junction of three province Shanxi, Hebeiand Henan, and they are endemic plants in Taihang Mountain, growing in the mountain slopes and the crevices of cliffs with an altitude of1000m.They bear great droughty tolerance and can grow in lean soils. Besides, they also have high ornamental value and medicinal value. Due to the reduction of its distribution range, they are endangered and have been nominated as the2ndclass protection plants in China.In order to research the genetic diversity and its genetic structure of Opisthopappus Shih populations, analyze the reason of being endangered, and to provide scientific theoretical basis of its germplasm resources protection and sustainable developmentand utilization,we analyzed diversity level of the6natural populations in Opisthopappus Shih using ISSR molecular marker technique. Main research results are as follows:27ISSR primers were used to amplify200individuals in6natural populations,and253bands were amplified of which230were polymorphic loci. The proportionof polymorphic loci (PPB) was90.91%. A relatively high level of genetic diversity was revealed in two species: O.taihangensis (Ling) Shih (PPB=90.12%, H=0.1842, I=0.289)and O.longilobus Shih (PPB=95.21%, H=0.2226, I=0.3542); AMOVA analysis indicatesthat the genetic variation is mainly within the two species, and the level of geneticvariation of O.longilobus Shih (84.95%) is higher than that of O.taihangensis (Ling)Shih (80.45%); A certain extent level of genetic differentiation (Gst=0.2740, Φst=0.196)was detected among3populations of O.taihangensis (Ling) Shih, but the level of genetic differentiation (Gst=0.1034,Φst=0.151) among3populations of O.longilobus Shih ismuch smaller than O.taihangensis (Ling) Shih. It is closely related to its special livingenvironment, the way of reproduction and spreading. The different levels of gene flow (1.325and4.336) and the mating system of sexual reproduction lead to the pres ent genetic structure of O.taihangensis (Ling) Shih and O.longilobus Shih.The fragmented and special living environment do not cause prominently genetic differentiation, instead they help Opisthopappus Shih to adapt to special living environment, so that itcan maintain relatively high level of genetic diversity.The UPGMA cluster analysis and the Mantel test showed that genetic distance isnot positively correlated with geographical distance(r=-0.2419,P=0.1845). Man-made interference seriously impacts the effective size and updation of population, and then impacts the natural gene flow among populations. It may also be the important reason why the geographical distance was not correlated with genetic distance. The resultsof cluster analysis based on genetic distance showed O.taihangensis (Ling) Shih andO.longilobus Shih did not have prominently interspecific genetic differentiation, which could explain that interspecific differentiation happened later, and the differentiationspeed of hereditary character was slower than morphological characteristics. At last,we raise some suggestions and measures to protect its genetic resources.