| Sinojackia xylocarpa and 4 other populations which were Sinojackia huangmeiensis, Sinojackia microcarpa, Sinojackia dolichocarpa and Sinojackia oblongicarpa, which belong to Sinojackia were selected and their template DNA were made by CTBA method. Further more, the ISSR-PCR amplification system was improved.11 primers of ISSR were chosen to amply the template DNA of the selected varieties and the genetic diversity and structure of them were studied to offer basic information for the population reconstruction of Sinojackia xylocarpa in Nanjing where is this kind of tree's mode sample place. The results gained were as follows:(1) Improved CTAB method was used in extracting Sinojackia xylocarpa genomic DNA. Optimizing system of ISSR-PCR amplification which may fit the tree of Sinojackia xylocarpa genus:60ng template DNA,0.5μmol·L-1primer,0.2mmol·L-1dNTPs,2.0mmol·L-1MgCl,2μL 10×buffer, and 1U TaqDNA with a total volume of 20μL. Amplification were that initial denaturation were at 94℃for 5min and 30s at 94℃,45s annealing at 48-60℃(depending on the primer used),1.5 min extension at 72℃. A complete 7 min extension at 72℃, the samples were maintained at 4℃after 40 circles.11 primers of ISSR were chosen to carry the PCR amplification about the 50 Sinojackia xylocarpa trees in Nanjing and the cluster tree of UPGMA had been found. Two classes were appeared in the genetic distances of 0.2621. There were obvious distance between 3 of those trees and the others. The reason of that may be the 3 trees did not belong to the population of the Mufu mountain. Some trees from this place excepting the deflected ones were selected as the basic unit of founding population rebuilding research tactics.(2) Genetic diversity and genetic structure between Sinojackia xylocarpa and 4 populations of Sinojackia were analyzed by ISSR markers.147 loci were observed among the 162 samples from the 5 spices using 11 primers. As analyzed by POPGENE32, the Sinojackia xylocarpa's value of observed number of alleles, effective number of alleles, Nei's gene diversity and Shannon information index were 1.4422,1.2820,0.1611 and 0.2386, respectively. And the level of genetic diversity of Sinojackia xylocarpa was in the middle rank among the selected kinds of spices. Genetic differentiation coefficient (Gst) and gene flow (Nm) of Sinojackia were 0.5094 and 0.4816, respectively. There were obvious differentiation phenomenon among genus and spices of Sinojackia xylocarpa. The Nei's genetic distances of 5 populations ranged from 0.1405 to 0.4712. Dendrogram was built by UPGMA based on Nei's genetic distances. The results indicated that the genetic diversity of Sinojackia xylocarpa was moderate and in a low lever among 5 populations. However, it was higher than that of Sinojackia dolichocarpa and Sinojackia oblongicarpa which are wild population. And this is the feasible foundation for population rebuilding of Sinojackia xylocarpa.(3) The reasons for the Sinojackia xylocarpa being endangered may be as below descript: First, the outer coat of the seed of Sinojackia xylocarpa is thick and the deep dormancy characteristic of this seed. More over, the rate of germination is low after the seeds were transported which may also effect the reproduction of this kind of tree and the ability of self-regeneration of it's population. Second, it is difficult to restore for this kind of resources during a short time after it's environment destroyed and the excessive digging of human beings. For the long run, the policies about the population rebuilding of Sinojackia xylocarpa should be created based on the probable disappearance of wild population of this kind of tree.
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