Biosystematics Study On The Endangered Tree Species Cercediphyllum Japonicum

The ovule development process of Cercediphyllum japonicum were beginning in November in the area of Nanjing. The integument and nucellus were checked in the middle of April. In the course of ovule development, un-continual density election substances gradually appeared in cell walls, vacuole gradually become big and cell separated gradually marked. The length of fruit in two populations was markedly correlation to its breadth, and the amount of seed was not markedly correlation to its breadth or length.The shape of foliage coat hair in the facing of a quilt in the population of Changyang was different from that of in the population of Shexian and Xinning. It was flat and bending over, yet it was perpendicularity in the population of Shexian and Xinning. But the other six populations have not any foliage coat hair. There were not any middle type between the type of hairs and the type of non-hairs. Therefore, we couldn't divide the type of foliage coat hair as a variation.The flora characteristics of ten communities including BaoXing were studied, and it indicated that: (1) Component of flora comes from anciently, and there were a few relic species in its community. (2) Transition characteristic of flora were apparently. (3) Tropic types and temperate types were coexisted, and most of population gives priority to temperate types especially the type of north temperate. Simpson index, Shannon-Wiener index, comparability degree of community, Levins niche breadth index, Levins niche overlap index, Pianka niche overlap index, Horn niche overlap index and niche comparability proportion about population of SiChuan BaoXing, HuBei BaDong, HuBei ChangYang and HuNan XinNing were measured, and it indicated that species owning big importance value ordinary have breadth niche. And species owing breadth niche have higher value niche overlap than others.Based on the side veins, distance between leaf base and breadth, leaves length, leaves breadth and leafstalk length, populations initially could be compartmentalized three different niche types. Based on the angle of foliage, it could be compartmentalized two niche types.Improved SDS-CTAB method was better adapted to abstracting DNA from the leaves of cereediphyllum japonicum. Optimized RAPD reaction system based on orthogonal design as follows: The reaction system of 20μL was composed of 25mMMg²⁺2μL, 10mMdNTPs0.4μL, TaqDNA enzyme of 1U 1μL, 10×Buffer cushion 2.5μL, 0.5OD primer 0.8μL, about 25ng DNA 0.6μL. The optimized PCR procedure as follows: 94℃denaturalization in advance 3 minutes, one cycle, then 94℃denaturalization 30 seconds, 37℃anneal 15 seconds, 72℃extend 90 seconds, 40cycles, after 72℃extend 7 minutes, it was hold at 4℃. By the use of BSA in the reaction system based on the orthogonal test, the amount of TaqDNA enzyme cut down 60 percent.The amount of RAPD polymorphic strip was 328 and account 47.5 percent for the total. It was indicated that there was abundance of genetic variation in the nature community of cercediphyllum japonicum. Even gene biodiversity was 0.1282 in a population and 0.1181 among populations. The coefficient of gene polarization based on Nei was 0.4797. Account for 54.24 percent gene flowed among populations, and it indicated that the level of gene flow was lower among populations. The genetic distance among populations changed between 0.0402 and 0.3296. Namely that the biggest genetic distance was between Anhui Shexian population and Henan Jiyuan population, and the least of that was between Sichuan Baoxing Ganyanggou population and Sichuan Baoxing Lujingou population. The correlation about the genetic distance to the longitude and latitude were not markedly.Integrating the study of leaves phenotypic variation, entironment characteristics of varies population, genetic biodiversity and genetic distance, we compartmentalized the studied populations as three ecological race. That was to say, Xinning population and Shexian population as an ecological race, Changyang population as an ecological race and the others (it included Baoxing, Jiyuan, Badong, Huxian, Jinzhai, Tianmushan, Emei population) as another ecological race.