| Sabina vulgaris, belonging to Cupressaceae, Cypress Family, is a naturally unique ever-green coniferous herb in Mu Us Sandland and plays an important role on preventing desertification. The principle objective is to reveal genetic differentiation of S.vulgaris population in development stage and provide scientific foundation in establishing protection strategy of S.vulgaris resource and breeding choiceness cultivar.According to color character and development stage, the development stages of S.vulgaris were ploted 4 stage named Salix cheilophila shrub(A), Salix cheilophila + S.vulgaris shrub(B), S.vulgaris + S.cheilophila shrub(C) and S.vulgaris shrub(D) respectively. We studied 4 different development stages (total number is 91 individuals) of S. vulgaris by using Random Amplified Polymorphic DNA (RAPD). Sixteen random primers were selected in the ampliphication, and 174 repetitive loci were produced in which 167 were polymorphic. The data were analyzed by the POPGENE3.2 Version1.31. The results showed that:(1) The genetic diversity of S. vulgaris population was high (95.98%). The percentage of polymorphic loci in each S.vulgaris development stage ranged from 77.59% to 89.08 %.The highest is A stage, the lowest is D stage ; Shannon diversity index and Nei`index have same order, the order is A>B>C>D;(2) The genetic differentiation among development stages was small, Gst=0.1187, 88.13% of which were within development stages; in other word, there are 11.87% genetic differentiation existed among development stages and 88.13% genetic differentiation existed within development stages. The gene flow ( Nm*) was 3.7122>1 and indicated more gene exchange among development stages, which prevented genetic differentiation among development stages;(3) The genetic distance between C and D is the smallest (D=0.0409), and the highest is between A and D (D=0.0866). And the genetic identity was high(0.9170～0.9599); The results of cluster analysis demonstrated that genetic relationship was closely between development stages;(4) We found S43-10,S282-10,S283-11,S297-4,S452-1,S59-1,S48-4 existed in all S. vulgaris which can be considered as characteristic loci, and the change trend of loci in different development stages is different. S448-1 is only existed in A development stage which is a reference used for determining different development stage. The dominant gene in different development stages is different, the proportion is as followed: 46.55%(A),29.89%(B),24.14%(C),29.31%(D);(5) We disparted 9 age class through 10 years as an age class, we analyzed the relationship of gene frequency and age class by graph theory principle components analysis. The results were: S450-1 showed negative correlation with the age class and S297-1 showed positive correlation with the age class.(6) The main intimidatory causation of S. vulgaris is not existed in self genetic variation but in destroyed habitat, pollution and excess using of biological resource. So we can protect habitat to save S.vulgaris resource.
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