| Ginkgo biloba, which is now unique in Ginkgopsida, is referred as a " living fossil" plant. As a wild species, Ginkgo biloba is native to China. 90 individuals of 6 populations, including possible wild populations and cultivated populations, with some individuals from inside and outside of China were analyzed by inter-simple sequence repeats (ISSR) and random amplified polymorphic DNA (RAPD) markers to determine the genetic diversity and genetic variations of among and within the populations. In addition, the status of ginkgo resource in China has been investigated in this study.1. In China, provinces such as Jiangsu, Shandong, Guangxi, Hubei, Henan and Zhejiang etc. are the main producing areas of ginkgo. While the natural resource of ginkgo mainly distributes in West Tianmu Mountain in Zhejiang Province, Wuchuan County in Guizhou Province, Dahongshan in Hubei Province, Songxian County in Henan Province and Jinfoshan in Chongqing.2. A total of 88 loci (including 65 polymorphic loci) were amplified using 13 ISSR primers for ISSR and a total of 97 loci (including 66 polymorphic loci) were amplified using 12 random primers for RAPD. The average percentage of polymorphic bands (PPBs) are 71.6% for ISSR and 68% for RAPD respectively. The genetic diversity of ginkgo at specie level (HE - 0.2485, Ho = 0.3701) and population level (HE = 0.1849, Ho = 0.2706) revealed by ISSR are all higher than those by RAPD (specie level: HE = 0.2220, Ho = 0.3366; population level: HE = 0.1647, Ho = 0.2397) . Therefore, ISSR molecular markers are more suited than RAPD molecular markers when testing the genetic diversity of ginkgo populations and determining the genetic relationship of among populations or among individuals which are much similar hereditarily. Correlation coefficient between genetic distance from ISSR and genetic distance from RAPD was 0.5621 (P=85%).3. The data of ISSR and RAPD molecular markers was compared with that of RAPD for other kindsof gymnosperm. Data both from ISSR and from RAPD especially from RAPD suggested that the genetic diversity of ginkgo was at a higher level. Although results from ISSR and RAPD analysis showed that the genetic diversity of WC and TM was higher than others' , there was no significant difference from among the populations TM, WC, DH and SX..Of all the populations the level of genetic diversity of TX was the lowest. Considered of the genetic diversity of the 4 possible wild populations combined with the ecological environment of their habitats, populations WC and TM are regarded as the survival habitats in glacial period.4. The genetic variation among the natural populations of ginkgo revealed by Nei's analysis and Analysis of Molecular Variance (AMOVA) (ISSR: GST = 0.1799, ST=16.3%; RAPD: GST = 0.2584, ST = 27.6%) was greater than other kinds of gymnosperm. Of all the 90 individuals, most individuals from a population can clustered together in the dendrogram of genetic relationship. It showed that among these populations there is great genetic variation. In particular, the genotype of TX population has been specified. Therefore, the genetic differentiation between TX and other populations is the greatest. The genetic differentiation of among populations might be caused by human selective pressures and barriers to gene flow.5. In general, the natural populations of ginkgo can survive in nature as long as they are let to be alone. So natural populations of ginkgo protected in situ is advised. The result of community investigation shows that the ecological environment in Wuchuan County is most fit for the development of natural ginkgo. Also because of the highest level of genetic diversity of WC population, establishing a conservation area here is necessary. In addition, base on the certain level of genetic differentiation of among the 4 possible natural populations, it is advised that adult plants or seedlings of ginkgo be transplanted mutually in order to enhance the gene flow among them and preserve the genetic diversity of ginkgo furthest.
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