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Genetic Diversity Of Picea Crassfolia

Posted on:2006-02-04Degree:MasterType:Thesis
Country:ChinaCandidate:P LiFull Text:PDF
GTID:2133360155451872Subject:Forest management
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Picea crassfolia Kom belongs to Spruce genus in Pinus family. It is a peculiar tree species in our country and widely distributes in the Northwest. it has so many virtues such as fine limber, long life-span, the tall and straight trunk, beautiful appearance, cold and drought resistance and so on. It is an important greening tree in urban and rural areas in Northwest and often makes up the large stretch of pure forest in alpine area. It forms the dark conifer community in Northwest. So understanding the genetic diversity of Picea crassfolia is of significance to protect the germplasm resources and breeding work in the future. The genetic variation of Picea crassifolia among 17 natural populations (Qilianshan, Datong and Gannan) was studied, based on polyacrylamide gel electrophoreses in the present work. Eight isozyme systems: Alcoholde hydrogenase (ADH), Glutamate dehyrogenase (GDH), Isocitrate dehyrogenase(IDH), Malate dehyrogenase(MDH), Esterase or Colorimetric (EST), Formate dehydrogenase (FDH), Suprroxide desmutase(SOD) and Aspartate aminotransferase (AAT) express 12 gene loci. The data were analyzed by software Popgen32. The indices adopted to evalute the genetic diversity invoved percentage of polymorphic loci, mean number of alleles per locus, mean expected heterozygosity per locus and mean observed heterozygosity per locus and so forth. The conculation as following: 1) The mean number of alleles per locus (A) was 1.7605. The percentage of polymorphic loci (P) was 45.83%. The average expected heterozygosity and oberved heterozygosity were 0.2101 and 0.2180 respectively, they were so similar. Therefore the phenomenon of inbeeding was so popular in Picea crassfolia populations. The fixation index ( F ) was 0.0029>0, which indicated that there was lack of heterozygote in Picea crassfolia populations. The differentiation degree of fixation index showed that the whole population consistented with the Hardy-Weinberg equilibrium and the percentage of random mating was not high. 2) The mean value of Gst over all loci was 0.0643 approaching to 0.1, which proved that most of the genetic variability(93.58%)existed in individual populations and a small proportion (6.43%) among populations. The division level of Gst denoted that the genetic differentiation of Picea crassifolia was relatively low. 3) According to the genetic identity and the analysis of 17 populations with unweighted pair-group method with arithmetic avaraging (UPGMA ),the results showed that the genetic distances were so approximate in the populations from the same location, and they clustered together. Basically, the nearer spatial distance was,the closer genetic distance they had. This was identical with spatial distribution pattern. However, the relativity was not evident, baesd on the Mantel test between geographical distance and genetic distance of Picea crassfolia. 4) There was not prominent correlation between the genetic diversity indices of Picea crassifolia( the mean number of alleles per locus, the percentage of polymorphic loci and the average expected heterozygosity )and attitude and latitude.
Keywords/Search Tags:Picea crassifolia, Allozyme, Genetic variation, PAGE
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