ISSR Analysis Of The Genetic Structure Of Xanthium In China And Somatic Embryogenesis In Camellia Sinensis

In this experiment, 16 populations of wild xanthium, including 2 species and 1 variety [Xanthium sibiricum Patr., X. mongolicum Kitag., X. sibiricum var. subinerme (Winkl.)], were collected from 15 provinces of China for the genetic diversity of Xanthium populations by the analysis of inter-simple sequence repeats (ISSR ); and the preliminary study on the direct somatic embryogenesis from immature embryos were carried out in Camellia sinensis cv. Tieguanyin, and the morphological and anatomic observation of the somatic embryogenesis was also conducted. The main results were as follows:1.The genetic diversity of Xanthium populations by the analysis of ISSRThe ISSR-PCR system of Xanthium was established and optimized according to the characteristics of Xanthium, which was applied to examine the genetic structure of 16 populations, and the results demonstrated that the genetic structure of Xanthium populations of china was as follows: the mean Shannon Index of diversity (I) was 0.0738, while population Shannon Index of diversity (I) was 0.35; Shannon Index of diversity (I) of the population of Guanxiguilin was the highest. By analyzing the gene frequency matrix, observed number of alleles(na), effective number of alleles(ne) and Nei's gene diversity(h), the results were similar. As a whole, no strong correlation was found either between all these polymorphic indices and Longitude or Latitude, but Nei's gene diversity (h) in the population 13 and 15 were the lowest because of island isolation. The results of Genetic diversity analysis showed that there were 68.41% of the variance among the populations and 31.59% of the variance in the populations respectively. Genetic diversity was rather higher in the Inter-population. The results were consistent with the AMOVA analysis. UPGMA cluster analysis (NTSYS) for 16 populations of Xanthium was carried out. We discussed the relationship among the morphology variance, the genetic variance and the chemical composition variance systemically.2. The study on somatic embryogenesis in Camellia sinensis cv. TieguanyinThe immature embryos were used as materials for inducing callus in Camellia sinensis cv. Tieguanyin, which was the main production cultivar of oolong tea trees. The highest frequency of callus induction occurred on the medium with 0.05 mg/L2,4-D and 3 mg/LBA. The direct somatic embryogenesis system of tea trees was established and optimized the system by using the modified solid MS medium supplemented with 0.2mg/LIBA, 2mg/LBA and 500mg/LL-glutamine. The somatic embryos could also proliferate on the same cultural medium. The EDM5 medium was the best for maturation of somatic embryos. The morphology studies demonstrated that the somatic embryos could be classified into 5 types as follows: normal embryos, adventitious embryos, linked-embryos, multiple-buds embryos and callusised embryos. The anatomical studies showed that the direct somatic embryo and secondary embryos was generally originated from the cotyledon surface, and from single or multi-cells. The above study provided essential technical foundation for the microprapagation and genetic transformation of excellent tea cultivars.