| The tea plant is an important cash crop in the world. Long term of cross pollination and self-incompatibility, it makes China have abundant tea genetic resource, which is a tremendous fortune for our country. If we can rationally layout the resources, they will play an important role in the development of tea industry. In order to better use and conserve these resources, improve breeding efficiency of the high resistance, high quality and yield tea cultivars, construction core collection is an urgent affair for us. The main results of this thesis are as follow:1. After comparing the genetic diversity index, the optimal entire sampling ratio for the primary core collection of tea germplasm was 20%. In the 20% sampling ratio of primary core collection, 9 parameters were used to rank 25 germplasm pools from different sampling strategies. The best sampling strategy was tea growing areas with proportion logarithm. With this strategy we sampled 223 gemplasms from the 1048 well appraised accessions from China National Germplasm Hangzhou Tea Repository and Menghai Repository Branch .The represention and genetic diversity were evaluated using length of'three and a bud', weight of 100'three and a bud', flower diamemter, style length, contents of water extracts, caffeine, tea polyphenols, amino, the ratio of tea polyphenols and aminos. The result showed that the 223 germplasms had a high practicality and heterogeneity, they can represent the genetic diversity of 1048 original accessions.2. After screening from 62 pairs of EST-SSR primers designed mainly on our lab's tea plant EST suquening results, 24 novel primer pairs could stably amplify all tested accessions. Including these 24 pairs of primers, 31 pairs of EST-SSR primers were used to amplify 60 tea genetic resources originated from south western China to inspect the polymorphism and usability. Totally 137 alleles were amplified, the number of alleles per primer ranged from 2 to 8, on average of 4.42. The polymorphism information content (PIC) varied from 0.09 to 0.85 and the observed heterozygosity (Ho) ranged from 0.07 to 0.94, on average of 0.63 and 0.53, respectively. The primers had a high level of polymorphism. At same times, these 24 pairs of EST-SSR primers were used to cross-amplification among six other closely related species and varieties in section Thea genus Camellia, the study indicated the 24 pairs of primer had a high universality. From all of which, the 31 pairs of EST-SSR primers can be used for genetic relationship analysis and molecular validation of core collection of tea germplasm.3. A total of 27 primer pairs were subjected to amplify all 414 accessions of primary core collections of 2665 accessions tea germplasms which were preserved in the China National Germplasm Hangzhou Tea Repository and Menghai Repository Branch. The PIC varied from 0.11 to 0.75, with a mean of 0.55, the average He was 0.58, which all showed that China have genetic abundant tea genetic resources. According to the amplified data, the Neighbor-Joining method was used to construct the dendrogram through UPGMA method. A total of 360 accessions were selected as preliminary core collections of tea germplasm at the genetic similarity coefficient of 0.80. The appraised result showed that the core collections had a good genetic diversity, which could well represent the primary core collection and original germplasms.
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