| Cupressus chengiana S.Y.Hu, a long-lived conifer of the genus Cupressus in Cupressaceae, is an endangered species endemic to Sichuan and Gansu Province in China, which has been nominated as the 2nd class protection plants in. The nature populations of C. chenegiana distributed restrictedly to the upper reaches of Minjiang, Daduhe and Balonghe rivers. C. chengiana is tolerant of drought and coldness so that it can grow in various sorts of droughty and lean soils, even on the petrous apertures. And it is one of the most important plants for forestation, soil and water conservation in the dry valley in Sichuan province, because of its fine capability of water resources conservation. In the past years, it had been used to built temples, boats and lots of traditional Chinese farm tools for its fine woodiness and special balm. Recently, the distribution areas of C. chengiana dwindled gradually and individuals became fewer sharply owing to badly destroyed environments, over-logging, grazing and its biological characteristic.The knowledge concerning about C. chengiana's genetic backgrounds were still unknown. In the DNA level, the genetic diversity and genetic structure of C. chenegiana populations was studied by AFLP markers. The aims were to illuminate the genetic background of C. chenegiana and analyze the endangered mechanism, which offer genetic evidences for the conservation implication. In order to protect the sources of C. chenegiana, the conditions of seed germination and callus inducement were discussed. The results were as follows:1. The extent of genetic variation and genetic structure within and among 8 nature populations was assessed using AFLP (Amplified Fragment Length Polymorphism) analysis. 4 primers produced a total of 274 scorable markers, 195 of which (PPB=71.17%) were polymorphic. Genetic differentiation (Gst) among populations detected by Nei's genetic diversity analysis was 0.4748, partitioning of molecular variance by AMOVA analysis indicated significant genetic differentiation within populations (60.87%) (P<0.01). Gene flow (Nm) was 0.5532. Samples from the same population mostly clustered in the population-specific cluster, and genetic distance was positive correlated with the corresponding geographical distance (R=0.75, p=0.03). Based on genetic diversity and genetic structure of populations of C. chengiana, we found that the spcies-level genetic diversity is relative high, but low in population level and the variation among populations was significant, which indicated that the man-made interference was a major reason why C. chengiana was in severe danger.2. The asepsis seeds were inoculated on seven MS medium with different hormone components. The results showed that the seed germination was actively stimulated by Gibberellin(GA)and significantly inhibited by Abscisic acid (ABA), While 6-benzy-laminopuzine (6-BA) had an active role in promoting seed germination. The asepsis young plants from seed germination wereinoculated on twelve different kinds of culture medium made up of MS and different hormones, so that the most fitting induction medium can be selected. As the results, 2,4-D had the crucial effect in callus inducement.
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