The Study Of Genetic Diversity And Genetic Differentiation Of Artemisia Songarica Schrenk. And Its Closely Related Species

A. songarica Schrenk.,A. ordosica Krasch. and A. sphaerocephala Krasch. are subshrub belonging to section Dracunculus of genus Artemisia. They are also edificators species of sandy vegetation and important wind-resistant and sand fixation plants in desert region. The three species have similar morphological characteristics and their distributions replace each other in geographical distribution. In this paper, ISSR and RAPD molecular markers were used to analyze the genetic diversity, genetic differentiation and kinships of three closely related species including 15 populations. The results are as follows:1. The three species had higher genetic diversity and the proportion of polymorphic loci of the three species was more than 98%. This have a great deal to do with the wind pollination characteristics of the three plants, and is also the key reason why the plants of Artemisia as dominant species have a good ecological adaptability and strong evolutionary potential in the sand area.2. The coefficient of genetic differentiation among populations were calculated based on Shannon index and AMOVA analysis for two molecular technique. The results showed that most genetic variation was within populations (differentiation among populations accounted for 7.96%-20.69%). The genetic identity between populations of the three species was more than 94% which indicated that the genetic differentiation among populations of the three species were small. The genetic differentiation order of the three species was A. songarica >A. sphaerocephala >A. ordosica according Shannon index for both of the two markers. But the results of AMOVA analysis for RAPD was different and the order became A. sphaerocephala >A. songarica >A. ordosica. The difference mainly came from A. sphaerocephala (RAPD:Фst = 14.31%,ISSR:Фst = 7.96%).3. The correlation between the geographical distance and genetic distance was analyzed by Mantel test for the three species, the result showed that A. songarica and A. ordosica had significant positive correlation, while A. sphaerocephala had not correlation.4. The correlation between two molecular markers technique was tested based on genetic distance of three species, the results showed that the two markers for A. songarica was greatly significant correlated(r =0.9081,P < 0.01) and that for A. ordosica was significant correlated(r =0.643,P < 0.05)but that for A. sphaerocephala was not correlated(r =-0.2981,P > 0.05) This suggest that gene fragments amplified by two markers are different to some extent and their reflection of the genetic structure also differ for different species.5. Cluster analysis based on two molecular markers indicated that the relationship of A. songarica with A. ordosica was closer than that of A. sphaerocephala with them.