A Study On Genetic Diversity Of Natural Population In Betula Luminifera

Betula luminifera is a fast growing deciduous broad-leaved tree species endemic to China. The remnant populations are generally fragmented and highly disturbed because of exploitation for timber and other species invasion. This study was conducted by morphological and RAPD markers with the same experiment materials (135 individuals of 9 natural populations) to determine genetic variation and population genetic structure of B. luminifera. The current situation and rules of the genetic diversity in the studied populations were revealed. Moreover, the application and utility of morphological and RAPD marker for analysis genetic diversity of B. luminifera were compared. These findings will provide scientific basic data for the germplasm resources conservation, genetic improvement and sustained utilization in B. luminifera. The main results of the research project were as follows.1. 15 morphological traits (seven leaf traits, three fruiting-cyme characters and five seed traits) from each of 135 B. luminifera trees in 9 natural populations were selected and investigated. Morphological diversity among/within populations was assessed. The extent and law of genetic variation in this species were also discussed. Results indicated that there was significantly difference in morphological characters among populations and within population. In different individuals within population, the CV of three phenotypic traits (in leaf, fruiting-cyme and seed) was 0.1779, 0.1056 and 0.1930, respectively. The traits stability of fruiting-cyme was higher than that of leaf and seed traits. The mean morphological differentiation coefficient Vst of populations was 0.3503. And it also showed that the variation of among populations (35.03%) was greatly smaller than that within population (64.97%). The CV among 9 populations followed as: WP(0.1288)>YA(0.1264)>LC(0.1153)> YX(0.1126) > SW(0.1078) > WY(0.0966) > MX(0.0953) > SX(0.0755) > SL(0.0509). There existed correlations among 15 morphological traits. And the phenotypic traits were also remarkably correlated to both longitude and latitude. The UPGMA cluster analysis showed that three groups could be divided from the nine populations of B. luminifera.2. The methods of storing samples and extracting total DNA of B. luminifera were established by comparing experiments. The optimal reaction system and amplification procedure conditions of RAPD for B. luminifera were also constructed by comparing the optimum parameters.2.1 Six methods (such as basic CTAB method, modified CTAB methods as CTAB â… , CTABâ…¡ , CTAB â…¢, CTAB â…£ and improved SDS methods) were used to extract high-quality DNA from the fresh leaves of B. luminifera. The DNA samples obtained by the above methods were tested by...