Parvifolia Genetic Diversity And Its Resource Protection And Utilization

Buxus sinica var. parvifolia was a rare, endangered and endemic tree species in China, which belonged to semi-rock plants. Through extensive investigation of its natural distribution, 7 natural populations and 1 cultivated population were selected to analyse phenotypic diversity and genetic diversity of B. sinica var. parvifolia at the morphology and molecular level. From aspects of molecular ecology, population ecology, rejuvenation and cutting propagation, the conservation and utilization of B. sinica var. parvifolia resources was systematically studied. Combining phenotypic marker and molecular marker, the taxonomic status and naming of B. sinica var. parvifolia relevant groups were researched. Based on the above study, the conclusions were as follows:①The phenotypic variations within populations or between populations of B. sinica var. parvifolia were rich, the differences of 17 branch and leaf characters in 8 populations were significant, the coefficients of variation were comparatively big.②21 RAPD primers were selected for genetic diversity analysis of 8 B. sinica var. parvifolia populations which amplified 176 (84.21 %) polymorphic loci; 21 ISSR primers were selected for genetic diversity analysis which amplified 397 (91.89 %) polymorphic loci. Using POPGENE, Shannon's information index within population was 0.3039, which accounted for 51.39 % of total genetic variation; Gst was 0.2723; Nm was 1.3933 (RAPD); Shannon's information index within population was 0.3368, which accounted for 82.51 % of total genetic variation; Gst was 0.1627; Nm was 2.5741 (ISSR). Applying AMOVA, the variation within populations was 62.65 %,Φst was 0.554 (RAPD); variation within populations reached 77.65 %,Φst was 0.223 (ISSR). The dendrogram based on Nei's genetic distance with interceptionλ= 0.1653 (RAPD) / 0.0503 (ISSR), 8 populations of B. sinica var. parvifolia from different regions could be divided into 2 categories: one was composed of populations from Shennongjia Moutain, one was composed of populations from B. sinica var. parvifolia in East China.③The clustering results of phenotypic markers showed that: the shape of cultivated B. sinica was stable and consistent, and the differentiation between populations was less; B. sinica subsp. aemulans and B. bodinieri were relatively consistent in morphology; the variations of phenotypic characters of B. sinica var. parvifolia were big. All UPGMA, NJ and PCA strongly supported the monophyly of distinct clade within B. sinica var. parvifolia in East China that conflicted with the existing taxonomic unit assignment only based on morphological characteristics, and clustering results of the other taxa were basically consistent with classical taxonomy.④The natural populations of B. sinica var. parvifolia had two peaks in mortality curve: the first mortality peak of population was during the stage of seedling and sapling, and the second mortality peak in different populations varied in time and intensity. The survival curves of populations were between Deevey-II type and Deevey-III type.⑤Around the time of callus forming and the root projected epidermis, the levels of IAA, ABA and GA4 between the initial generation and the subsequent generation had obvious differences, and presented certain rules. Fv, Fm, Fv / Fm, Fv / Fo, Fm / Fo these five parameters from the initial generation to the subsequent generation showed a gradually increasing tendency. The time from T phase to P phase of fluorescence induction kinetics was progressive shortening with the continuous generation cuttage proceeding, decrement of oscillation was gradually accelerated.⑥In spring cutting rooting process, around the time of callus forming and the root projected epidermis, the levels of IAA, ABA and GA4 in different cultivars and treatments had obvious differences, and presented certain rules. In summer cutting rooting process, the rooting effects of cuttings in matrix composed of vermiculite and perlite treated by exogenous hormone especially IBA + BA were increased; in cutting matrix of light loam, hormone treatment effects of IBA + BA and ZZHY were comparative good.