Studies On Lagerstroemia Germplasm And Establishment Of Core Collection In L. Indica And L. Subcostata

The crape myrtle is native to China,it is one of the hereditary variation centers with extremely rich resources. The crape myrtle is one kind of trees with high admiring value, it blooms in hot summer, its color is gorgeous,and the florescence often amounts to hundred days. The crape myrtle has hard resistance and wide adaptability,resources disperses and has been destroyed. The studies on the basis of resource data and the wild inspection, according to two levels including populations and among individuals in populations, materials of natural 10 Lagerstroemia indica populations and 3 Lagerstroemia subcostata populations were collected, the phenotype diversity and hereditary diversity analyses based on DNA molecular marker were carried out, a preliminary core collection was established, the protecting tactics of hereditary diversity were suggested. The main results were as follows:1. By inspecting the references and the investigation,the genus of I. included 19 species native to China,4 species were introduced,was totally 41.82 percentage in the world;According to the investigation, L. stenopetala is the only one species with flavor and should be strongly protected and studied; L. venusta,L. villosa blossom in winter with their special blooming period, the fine gene can be used for germplasm innovation; through the investigation, 51 L. cultivars were determined, 22 cultivars were in line with the names which had been published by Wang Xian, the other 29 cultivars were given names after deliberation within the group of L..2. L. indica and L. subcostata populations had very high genetic diversity among populations. The mean phenotypic differentiation coefficient (V_ST) showed that the variation among L. indica and L. subcostata populations was higher than that within population; The correlation analysis between geographical factors and the morphological characters of L. indica and L. subcostata populations were conducted, the result showed that inflorescence length, petal length, flower diameter, calyx length were significantly correlated.3. Totally 13 populations were selected and analyzed by amplifications using 7 pairs of AFLP primers. As for, Shannon's information index (I) were 0.5898 and 0.5952, Nei's gene diversity index (H) were 0.4133 and 0.4083, genetic differentiation coefficient among populations (Gst) were 0.5415 and 0.8251, the variation among separately L. indica and L. subcostata populations were 71.74 and 79.69 percent of the total variation. There were higher genetic diversity among separately L. indica and L. subcostata populations.4.Totally 51 cultivars were collected. Using flower color as an important criterion for the classification was very reasonable; the propagations of complex colored cultivars were regarded as one important target because of their high ornamental value. According to the principal components analysis, 25 characters were selected from 41 characters. Q cluster result showed that 51 cultivars were divided into 3 groups, the first group included hybrids between L. indica and L. limii; the second one included cultivars within L. indica; the last one included cultivars within L. subcostata, it was coincide with the original L. cultivars classification principles. R-cluster analysis indicated that the choice of characters was reasonable, since smaller number of samples, there were limitations, the research in future need choose the observed characters,the characters of flowers should be emphatically chosen in the evolution of evolutionary traits; Through pollen morphology, the author observed that morphological differences between the species were not obvious, pollen shape and species of flower color were not related, not species having outstanding traits had not unique pollen morphology, it was difficult in classification and identification only according to pollen morphology; The results of AFLP on 51 L. species using 5 primer pairs show that polymorphic loci percentage was 61.4%. All the above cultivars were divided into 3 groups. It was verified that the previous studies regarding provenance as first-class classification was reasonable from the molecular level.6. The sampling strategy was based on study of the genetic diversity in 10 L. indica populations and 3 L. subcostata populations, the results showed that there had high genetic diversity among L. indica populations separately and 3 L. subcostata populations. Genetic differentiation among populations was at high level, genetic diversity was maintained among populations, and so more populations as far as possible should be included in the core germplasm protection strategies; According to surveys in China collection of 513 L. germplasm individuals based on basic characteristics of data resources, phenotypic characteristics in accordance with the division groups and the principle of sampling systems division,the two indicators including genetic diversity and genetic richness were calculated, 151 individuals were chosen as the primary core collection,after testing the primary core collection were able to represent the total germplasm range of genetic variation.