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Studies On Genotypic Diversity Of The Rhizobia Isolated From Caragana, And The Dynamics Of Nitrogen Fixation Ability To Root Nodule Of Caragana Microphylla Lam.

Posted on:2006-02-28Degree:MasterType:Thesis
Country:ChinaCandidate:L TaoFull Text:PDF
GTID:2120360152992235Subject:Grassland
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This thesis reviewed the study development of Rhizobium sp.( Caragana), and compared the main methods applied in rhizobial genetic analysis; The nitrogen fixation ability of root nodule is investigated on different development stage of Caragana microphylla Lam. and at different age of tree; Rhizobia isolated from Caragana korshinskii in Shanxi and Inner Mongolia Province of China were studied on the basis of genetic and phenetic feature, to reveal their diversity. The results will provide the scientific basis during develop and use the kind of rhizobia resources.1. The results of the nitrogen fixation ability investigation are as follows: during plant development, the peak values of nitrogenase activity appear in blooming stage. At this moment. nodule fresh weight is the most, plant N and soil N are the highest. And it is obviously higher than other stages; the peak values of plant biomass appear in Fruit Bearing Stage; About nitrogen fixing ability of root nodule, Biennial plant and 5-yr-old plant are stronger than triennial plant and 4-yr-old plant. Plant biomass has a trend to increase with growing age, but plant N has a little decreasing trend.2. The results of phenotypic characteristics showed that 88% of strains could not grow on Broth Culture Medium; 69.7% of strains produced the acid, 12.9% of those produced alkali; 72% of strains could grow well on YMA with 5.0% NaCl; The relationship between geographic distance and genetic distance were not remarkable(R~2=0.0167), 1.67% of hereditary aberrance could be explained by geographic distance, the others would be decided by other facters.3. Digested by four restriction enzymes, all the Caragana rhizobia strains studied were claddified into 30 16S rDNA genotypes, showing rich genetic diversity. The dendrogram derived from PCR-RFLP of 16S rDNA showed that the clusters of above 86% of strains agreed with that of numerical analysis of phenotypic chatacteristics. 69% of strains were clustered within the phylogenetic branch of Mesorhizobium, 16% of strains were clustered within the phylogenetic branch of Rhizobium, Only one strain was clustered with Bradyrhizobium at the similatity level of 87%.
Keywords/Search Tags:genetic analysis, Caragana korshinskii, rhizobia, nitrogen fixation ability, 16S rDNA, RFLP
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