| Magnolia wufengensis is a new Magnoliaceae species found and nominated by Lu Yi Ma and Luo Rong Wang in Wufeng county, Hubei province, China. Because of the special particularities of its distribution region, the narrowness of its dispersal area, the scarcity of its individuals and the dangerousness of its population extinction and its high ornamental value and enormous economy worth, the research on M. wufengensis should be taken in salvage way immediately. The distribution of germplasm resource, the differentiation of morphology, the population diversity and differentiation, and the relationship with other Magnoliaeceae species were carried out in this study. The objective of this study is to provide a theoretical base for the research and utilization of M. wufengensis, for the germplasm conservation, for a proper taxon status in Magnolia and for some new breeds selection and culture and the next multipurpose exploitation. This paper also provides groundwork for the synthetic multi-subject study on M. wufengensis.The wild germplam resource of M. wufengensis was investigated, the rich variations of its morphology were observed, and the population areas were plotted out according its natural distribution; then ISSR and SRAP markers, agarose gel & polyacrymide gel and 4 dominant marker data analysis methods were applied to analysis the population diversity; finally, the relationship with other Magnoliaceae species was estimated based on ISSR and SRAP markers and rnDNA ITS sequences.Field investigations showed that M. wufengensis is mostly distributing in the midst and west of Wufeng County and some parts border with Changyang County. M. wufengensis is an endemic species of Three Gorge Area and narrow distribution only in this area. Trees of M. wufengensis are mostly scattering at the waist, brae and bottom of mountains with an altitude from 1400m to 2000m, and distributing in single or population way according to the intension of human activity. Morphological observation indicated that a rich series of variance are holding in wild M. wufengensis population including variations of flower form, number, color and shape of tepal, et al.Population genetic analysis showed that a fairly high genetic diversity were maintained in M. wufengensis population, and the average percentage of polymorphic loci was 86.2%, the total heterozygosity was 0.3137, and the average within population heterozygosity was 0.2821; the population structure analysis showed that the differentiation among populations was low and the FST was 0.1008, which means 89.92% of the total variation was within population and only 10.08% of the total variation was in among population. These characteristics provide a plenty of materials and a practice policy for conservation and breeds selection.The species relationship based on ISSR and SRAP markers illustrated that there is a more close relation between M. wufengensis with M. denudata, M. sprengri and M. sprengri. var. enlongata; and a more near connection between M. wufengensis with M. biondii and M. sprengri revealed by ITS sequences. Clones of the ITS sequence within species of Magnoliaceae were different obviously, combined this difference with chromosome number data, and a reticulation revolution in Magnoliaceae species was deduced.A conservation strategy for M. wufengensis was proposed according to the high diversity and the low differentiation of population genetics. The conservation for M. wufengensis ought to take protection and maintain the high population genetic diversity as the kernel of conservation and pay in situ equal attention to ex situ conservation. During in situ conservation, protection for the integrality of existing population should be put into the first degree, and the wild trees with their habitats should be protected together. As ex situ conservation, combination its excellent ornamental value, an industry of M. wufengensis should be developed vigorously. And so, the population will be growing more and more large in the course of exploration and application.The experimental methods and the statistic analysis for dominant molecular markers were compared systematically in this thesis. The ISSR marker system were optimized, and the advantages and disadvantages of ISSR and SRAP markers were compared, and so as to agarose and polyacrymide gel, 4 statistic methods including the square root (SR) method, the Lynch & Milligan (LM) method, the Bayes method and the based on bands phenotype AMOVA method. According to the contrast results, three opinions about dominant molecular markers in population genetic were put forward. one is the SRAP is a more suitable marker than ISSR; the Polyacrymide gel which has a higher resolving power as a separation medium and recommended to be used; the Bayes method is a more proper molecular markers than the three other motheds. The objective of these comparisons is to provide a foundation for construction a unified platform of dominant marker both experimental and statistical method for population genetic analysis. |
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