ISSR Analysis Of Genetic Diversity Of The Traditional Chinese Medicinal Plant Ligusticum Chuanxiong Hort.

Ligusticum chuanxiong hort., family Umbelliferae, is a well-known traditional Chinese medicinal herb with hemodynamic and analgesic effects. It is widely distributed in China, mainly in Sichuan, Gansu, Jiangxi, Jilin, Jiangsu, Yunnan, Guizhou Province. It has been prescribed for treating various cardiovascular diseases such as ischemic stroke, dysmenorrheal, migraines, menstrual disorders, angina pectoris, amenorrhea, rheumatic arthralgia, headaches, and abdominal pain with mass formation. In the present study, inter-simple sequence repeats (ISSR) markers were used to investigate the level of genetic diversity and the pattern of genetic structure in 285 individuals from 17 populations of L. chuanxiong, which ranged most of its distribution in China, provided significant information of this species' genetic diversity which has not been researched before.Based on 10 primers, 186 ISSR bands were generated, 183 (98. 39%) were polymorphic. The value of Nei's gene diversity (h) equaled 0.27 at species level, indicating a considerable genetic diversity in this species. The high level of genetic diversity of L. chuanxiong maybe due to the following three reasons: First, the sampling range may lead the higher genetic variation as the distance between adjacent sample locations was at least 5 m to avoid sampling connected ramets. Second, somatic mutations can contribute more to standing genetic variation in populations than do gametic mutations and thereby can increase plant evolutionary rates. The long history of L. chuanxiong may also allow genetic diversity to accumulate without sexual reproduction. Third, in its main distribution areas, L. chuanxiong usually covers large areas. The enormous population will assist maintaining genetic diversity and reduce the effect of genetic drift.AMOVA analysis showed 46. 42 % of the total genetic variance existed among populations. It is probably due to the clonal propagated mode and lack of gene flow. Population genetic differentiation was not significantly correlated with physical distance of the populations according to the Mantel test, so physical distance can not account for the population genetic diversity.The knowledge of genetic diversity may redound to the domestication program for genetic improvement such as increase the amount of some certain medical component, enhance the adapt ability of some populations, in order to accelerate its worldwide usage.