| Vatica mangachapoi is a species of family Dipterocarpaceae distributed in Hainan Island, China. It is famous for its heartwood and forest by-product. Its forests decrease rapidly in area due to habitat destruction and fragmentation which result from over-harvesting and devastating forests for arable lands or orchards. The genetic resources are eroded heavily, this makes the species currently threatened with extinction, and the species has been listed in China Species Red List. Phenotypic Variation and the relationship between the diversity level and geographic and environment factors were studied using Phenotypic traits; Germplasm resources were collected, provenances of Vatica mangachapoi were selected based on the growth traits of Vatica mangachapoi provenances; genetic diversity and genetic structure were studied by SSR markers. Based on the Comprehensive analysis of phenotypic traits, seedling growth difference and SSR, the situation of the genetic resource of Vatica mangachapoi was analysed, This study would provide scientific evidences for coservation and management of natural populations of Vatica mangachapoi. The research shows the results as follows:1. 17 traits of fruit and leaf morphology were investigated in 9 natural populations of Vatica mangachapoi, the level of phenotypic diversity in its natural populations was assessed and relationship between the diversity level and geographic and environmental factors was estimated using nested analysis, multiple comparison test, correlation analysis and clustering analysis. The result showed: there were significant differences in variations of fruit and leaf morphology(totally 17 traits) within and among populations, indicating that abundant variation of these traits existed among and within populations; the variance within populations(50.57%) was greater than that among populations(11.38%), It was demonstrated from correlation analysis that there were significant positive correlations between leaf length and petiole length, ratio of leaf length and width and height of maximum leaf width, while the length of long fruit sepals were in significantly negative correlation with number of leaf lateral vein and petiole length. No obvious correlation was found between fruit and leaf traits and mean annual air temperature and precipitation. The 9 natural populations could be divided into three groups by UPGMA clustering analysis based on Euclidean distance calculated from phenotypic traits.2. The seedling growth performances of 10 populations were determined. The result of variance analysis showed significant differences of growth traits among populations, significant genetic divergence. Bawangling population showed the highest seedling height, root collar diameter, and biomass, and seedlings from Shimeiwan population grew slowly. Correlation analysis revealed that there were significantly positive correlations between seedling height, root collar diameter, biomass of root, stem and leaf, while no significant relationship between these traits and root-shoot ratio As well as between all 8 growth traits and environmental factor.3. One mixed dried leaf sample including thirteen individuals from 13 populations was applied to the SSR scan in whole genome level on the Roche 454 GS FLX plus platform. twelve SSR markers were developed. all these loci were successfully amplified in Vatica guangxiensis, an endangered dipterocarp endemic to southwestern China, natural distributed in Guangxi and Yunnan. Genetic diversity and genetic structure in 13 population of Vatica mangachapoi were analysed using 12 SSR markers. 121 alleles were found in 13 populations of all 12 loci, 6-16 alleles per loci. 34 in 121 alleles were private alleles, 1-5 public alleles per loci. 0-3 private alleles per loci, 14 private alleles in total. The number of the observed heterozygosity(Ho), the expected heterozygosity(He) and Shannon’s Information index(I) were 0.598, 0.698 and 1.416. The fixation index(F) was above zero of all populations. 93.3% of genetic diversity resided within populations(FST = 0.067), High gene flow promoted between the group of communication(Nm=3.621), reducing the genetic differentiation. Based on the Nei’s distance, 13 populations were divided into two groups, but the Geographically adjacent populations were not together.4. Vatica mangachapoi had a high level of genetic diversity and resided the majority of its genetic variation within populations based on the results of morphological traits, growth traits and SSR variation. The populations with high level genetic diversity should be focused on when implementing conservation of its genetic resource. Kafaling and Baishuilinchang population should be paid more attention because of their high level genetic diversity. And Shimeiwan population also should be paid more attention on account of more private alleles... |
