| Gleditsia sinensis, a unique native species of China with high economic and ecologicalvalues; is distributed continuously as scattered individual trees, particularly around villages. Atpresent, the natural resources of Gleditsia sinensis are being severely damaged because oflong-term over-exploitation, which also contributes to the loss of genetic diversity. In thepresentstudy, wild resources of Gleditsia sinensis in the southChina were investigated; thegenetic diversities were evaluated andthese results established basis foundation for theGleditsia sinensis resources protection, the genetic improvement and the screening of superiorgermplasms rationally and scientifically. Moreover, it is also provided the basement forexploiting the economic value of Gleditsia sinensis resources and its industrialized productionas the “forest-medicine” pattern in a large-scale area. Based on the multitudinous conservationmodel, the theory of field investigation, and natural distributionof scattered trees,215individuals with10populations of Gleditsia sinensis in the southern part of China wereconllected. The morphological diversity, the DNA diversity, the breaking dormancy of seed, theprogeny seedling growth traits, and the chemical constituents were studied. At the same time,out research provided the conservation strategy for genetic diversity of Gleditsia sinensis andconstructed conserving forests in different regions with more plots. The resultsare shown asfollows:1. The analysis of variances of all traits showed significant differences among/withinpopulations. The mean values of phenotypic differentiation coefficient for the eleven traitswere20.42%, and the variation within populations (70.58%) was higher than that amongpopulations (20.42%), which indicated that the variance within population was the main part ofthe phenotypic variation of the species. The variation ranges of CV among11traits were4.55%and18.38%, and the average was11.20%. The CV of pod within populations (14.75%) washigher than seed (6.95%)，which means that the seed has high stability. Most of the pod and seed traits were positively correlated. The seed was proved a west-east variation at samelatitude. The pod was proved a west-east variation at same longitude.2. The AFLP system was built and used for the amplification reaction in the experiment.There were totally219individuals which were selected and analyzed by amplification using14pairs of AFLP primers screed1782bands were obtained and1389bands (77.94%) of themwere found to be polymorphic. The difference of frequency reflected the difference of geneticstructure. The genetic differentiation coefficient amonge10populations (Gst) was26.87%, andthe variation within populations (73.13%) was higher than that among populations (26.87%)These results indicated that the variance within population was the main part of the variation ofthe species. As for genetic diversity parameter, the average effective number of alleles is1.261.The average number of alleles was1.714. Shannon’s information index is0.256and that ofNei’s is0.168. The gene flow (Nm) was1.483. The average genetic identities and geneticdistance were0.950and0.059, respectively. These results indicated that a certain degrees ofgenetic differentiation exist amonge the populations. Gui Zhou Xing Yin population was thehighest diversity and Guang Xi Gui Lin was the lowest diversity.3. There are differences between populations for chemical constituents. In the podchemical constituent, the average content of saponins, crude protein, and crude starch is thehighest in Guangxi population is8.13%,22.87%,36.91%respectively. The average of totalsugar in Hubei Jingshan population is the highest is16.36%. In the seed chemical constituents,the average content of crude protein is the higtest in Chongqing Xiushan populations is4.41%;the average content of crude fat is the higtest in Guizhou Xingyi populations is8.07%; theaverage content of pectin is the higtest in Gansu Tianshui populations is0.71%;the averagecontent of total suggeris the higtest in Hunan populations is34.76%The average content ofsaponins in Shandong Feixian is18.33%, which is the highest in all pupulations. Analysis theChemical constituents of seed and pod can provide an important theoretical basis for theselection of superior cultivars, efficient and comprehensive utilization of the development ofthis valuable plant resource. 4．The seed dormancy of Gleditsia sinensis could be broken through corrosion with highconcentrated H2SO4. The seed was95.70%, which was increased by88.00%than control afertreatment by concentrated H2SO4for two hours. The17days’ decrease in mean germinationdays and11fold’s increse in coefficient of germination speed after breaking skin. After treatedby sulphuric acid for120min, the optimum germination temperature was25℃, thegermination rate and germination power were95.70%and85.40%, respectively.5. The analysis of variance showed that there are significant differences between opulationand families within population for growth traits. There were differences of the growth traitsamong each family. The height ranges of CV among the populations were19.45%and34.15%,and the average was26.07%. The diameter s at ground range of CV among the populationswere10.35%and21.38%, and the average was15.09%. A significant negative correlation wasfound between the height growth and the latitude.6. Gleditsia sinensis genetic resource conservation programe should pay attention for theprotection of existing natural forest, forbiding logging reserved forests, while protecting theirhabitats. Sampling of seeds (or propagation materials) from more populations with a smallernumber of trees at each site is preferable except for in situ conservation. Conservationstands/gene banks, provenance/families trials, clone banks and seed banks shoud be established.While some botanical gardens and arboretums are also proposed to conserve the geneticresources of the species. The individual number of populations should be increased while thepopulations should be induced. The selection of good varieties should be taken seriously. It isparticularly important to protect the integrity of a population while the conservation. |
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