Studies On Genetic Diversity And Construction Of Core Collection Of Chimonanthus Praecox

Chimonanthus praecox is native to China and has been cultivated for more than one thousand years, which has beautiful color and intense flower fragrance in winter. It is the special famous traditional flower of our country. What's more, which cutting flower and potted landscape is special. but in recent years, the cultivars resources loss seriously, which number and name is unknown, the resources status is not clear. which wild resources encounters to destruction seriously. the genetic diversity level among populations,the natures of genetic variation among and between populations,the genetic diversity patten and the factors which affect genetic differentiation are still not solved. the international exchange of cultivars and the development and application of wild resources is affected seriously, the breeding of cultivars, especially the ornamental breeding is also hindered. So in order to avoid the resources loss and destruction furtherly, to protect the resources diversity, an overall investigation,analysis and evaluation on Chimonanthus praecox wild and cultivars resources of 13 provinces was carried out in three years , then by phenotypic,ISSR and AFLP two kinds of molecule markers .the phenotypic and genetic diversity among populations and within population were studied in this research. Finally pre-selected core collections of Chimonanthus praecox gemplasm in China were established based on phenotypic data of Chimonanthus praecox wild and cultivars resources . according to the rule of genetic diversity resources, Core collection of the cultivars resources was constructed ,and advancing the protect strategy of population samples and individual samples in population of the wild resources. Main results were obtained as follows:1.The investigation of the wild Chimonanthus spp germplasm resources of 13 provinces showed that Chimonanthus spp distributions are south to Qinlin and east to Hengduan mountains. The geographical distribution range is between26°26′and 32°00′N and from 109°34′to 119°37′E, The range includs the warm temperate zone, the north subtropical zone and the middle subtropical zone. Which has a wide range vertical altitude change between 700m and 2900m, of which the vertical change range of Ch. Praecox is the most higiest ,but the upper and lower limit of vertical distribution is not relevent to the latitude and longitude. Chimonanthus praecox often grows the abundant Hydrothermal conditions and belongs to the dominant components of the forest and shrub layer .which has a very strong self-renewal and multiply ability. Chimonanthus spp has 5 vegetation type . the difference of the flower variation traits and resource status among populations is Significant.Shennongjia population has the most abundant flower variation. Huaxi population flower scent is different from the other populations ,and Linan populations florescence is the most late in all populations. The resources in Shennongjia is destroyed seriously and should be protected as soon as possible. a new cultivar Chimonanthus praecox var. reflexa , and a new forma Chimonanthus praecox var. reflexa f. versicolor of Chimonanthus praecox were published.2.The investigation and arrangement of the existing cultivars were carried out, 62 Chimonanthus praecox cultivars were finished ,which were planted in the Xiaotangshan base in Beijing . the Q cluster analysis on the basis of investigation and nomenclation,R cluster analysis and the principal component analysis were carried out. the classification criteria of Chimonanthus praecox cultivars classification was established. A multifactorial appraisal system based on the Analytic Hierarchy Process was developed for cutting-flower cultivars of Chimonanthus praecox. 27 cutting-flower cultivars of Chimonanthus praecox were selected.3.The phenotypic diversity analysis showed that there was significant character difference among populations and among individuals within populations. The mean phenotypic differentiation coefficient(Vst) of 10 populations is 39.40%, The mean phenotypic differentiation coefficient showed that the variation among populations(55.13%) was slightly higher than that within populations(38.18%). which indicated that the variance within population is the main part of the phenotytic variation of Chimonanthus praecox. The correlation analysis between the phenotypic traits of Chimonanthus praecox and geography ecological factor showed that the correlation between them is not significant except latitude and annual rainfall. the UPGMA cluster analysis based on the euclidean distance of Chimonanthus praecox investigated could be divided into three groups.The flower variation analysis of 10 Chimonanthus praecox populations showed that there was significant difference on the Chimonanthus praecox qualitive and quantitive character among populations and among individuals within populations.4.163 pre-selected core collections of Chimonanthus praecox gemplasm in China were establishen based on the data of wild and cultivar resources. there are 77 wild collections and 86 cultivars collections ,which repectively takes 26.9% and 50.6%, According to the t-test of Shannon diversity index and the evaluation of character traits of ornamental characteristics, the pre-selected germplasm could represent the genetic variation range of the whole germplasm. 5.The genetic diversity of 7 wild populations and 2 cultivated populations were analyzed using inter-simple sequence repeat (ISSR) markers and amplified fragment length polymorphism (AFLP) markers. 124 bands were amplified by 11 ISSR informative and reliable primers ,of which 110 were polymorphic loci, percentage.of polymorphic loci (PPL) is 88.70% , Genetic differentiation mainly occurred within populations(GST=0.3536). 253 bands were amplified by three AFLP informative and reliable primers screened, of which 218 (86.17%) were polymorphic., Genetic differentiation coefficient among populations was 0.2906. Both molecule markers showed the genetic diversity difference among populations was high. The genetic diversity levels of population Shennongjia(SN) and Baokang(BK) were higher than other populations investigated. UPGMA cluster analysis the correlation between genetic distance and geographic distance among the populations was not significant .Finally ex situ and in situ conservation of wild Ch. Praecox populations were suggested.6.By using ISSR and AFLP markers, Core collection of the wild resources and the cultivars in Chimonanthus praecox was constructed seperately . According to the study of the population sample strategy and the individual sample strategy, 6 wild populations and 20-25 individuals sample in each population could hold more than 95% molecular marker variation diversity. Which can be used the primary core collection of wild resources in Chimonanthus praecox. Random sampling each group was used to screen the core collection of 86 Chimonanthus praecox cultivars germplasm.22 samples were chosen as core collection. T-test results by using SAS software results demonstated that the core colection could stand for initial collection excellently.The above study provides the theory basis for the selection of the priviledge population and the establishment of the sampling stategy, which has an important meaning for seeking and conservation of new cultivars and protection , the selection and breeding of eminent cultivars and usage of resources and their genetic relationships in Ch.praecox.