Studies On Genetic Diversity And Phylogenetic Relationships Of Boehmeria

Based on the difference in nrDNA ITS, we analyzed the phylogenetic relationships of Boehmeria; In the second part, by the usage of ISSR analyzing technique, we discussed the genetic diversities among 56 varieties of B.nivea. The thesis provide theoretical foundation for the evaluation, classification, selection of good rermplasm resources, utilization and protection. Major results were as follows:1. The nrDNA ITS sequences of the 14 species and 8 varieties of Boehmeria and one outgroup were obtained by PCR and sequencing, which subsequently were used to analyze the phylogenetic relationships in the genus by homologous blast and clade anlaysis. In the data set of 14 species and 8 varieties of Boehmeria, the percentage of phylogenetically informative is 28.9% in ITS regions (including two spacers, without 5.8S subunit). According to the above statistics, there are relatively abundant informative sites in the ITS sequences of genus Boehmeria. According to the well bootstrap support among the most of clades, which proved that the ITS regions are valuable to resolve the phylogenetic relationships in Boehmeria.2. According to the two ITS-based trees employing NJ and MP analyses: Pilea notata formed a single group, it has the most distant to the other species of Boehmeria. The 14 species and 8 varieties of Boehmeria formed four groups. The plants in Sect. Duretia and Sect. Phyllostachys formed the first monophyletic group; The plants in Sect. Zollingetrianae and B.tonkinensis formed the second monophyletic group; The plants in Sect. Tilocnide formed the third monophyletic group; B.malabarica formed a single monophyletic group, but it has the nearest distance to the plants of Sect. Tilocnide. Each clades has a well bootstrap support.3. The establishment of an optimized PCR reaction system for ISSR analysis: PCR was performed in a 25ul reaction mixture with 100ng DNA, 0.4μmol/L primer, 0.2mmol/LdNTP, 1U Taq DNA polymerase, 1.5mmol/L Mg²⁺, 1×buffer. The reaction process went as following: the temperature profile used for PCR was 94℃for 5 minutes, followed by 35 cycles of 94℃for 45 seconds, 56℃for 45 seconds, 72℃for 1 second, and was terminated with a 7 minute DNA extension step at 72℃.4. The primer sieving of B.nivea ISSR and amplification of PCR: in 56 experimental varieties, 258 DNA bands were amplified by 15 ISSR primers, in which 247 DNA bands were polymorphic, polymorphic ratio (PPB) was 95.82%. 17.2 bands were amplified by every primer. According to the widely distributing and adapting to various climate and soil condition of varieties of B.nivea, we can prove B.nivea heve strong adaption and genetic ability, potential of breeding amending. Based on the ISSR mark bands, the UPGMA cluster analysis was carried on, the results indicated that: the 56 varieties were divided into five groups by first combined line (D1=0.635). The fifty-one varieties in Hunan and Hubei province formed a group; the two varieties in Guizhou province formed the second group; the two varieties in Jiangxi and one variety in Sichuan formed three groups. The result was shown that there was relation of genetic relationship with geographical position.