Studies On Micropropagation And Rejuvenation Of Taxus Chinensis Var. Mairei

In this paper, Taxus chinensis var. mairei were adopted as experimental species focused on in vitro embryo culture, in vitro propagation system establishment and micrografting in vitro and invivo for tree rejuvenation induction. Preliminarily Taxus chinensis var. mairei in vitro propagation systems were established and the movement of rejuvenation of adult mature trees were observed. The main results obtained are presented as follows:1. Taxus chinensis var. maire seeds were treated in 2.5% sodium hypochlorite solution for 10 min in a vacuum was optimal disinfestation method with contamination rate 6% and germination rate 86%.2. WPM was selected as the best basal medium for embryo culture, the best embryo growth in vitro without cytokinin, combination of KT 0.1mg·L^-1 and ZT 1mg·L^-1 effectively induced more caespitose adventitious bud formation. Activated embryo effectively induced adventitious buds.3. MS was selected as the best basal medium on shoot growth; but the best basal medium for shoot proliferation was WPM; stem sections disclosed better proliferation than shoot tips; single cytokinin concentration ZT 3mg·L^-1 resulted in most effective on shoot multiplication to 4.80 folds, Combination of ZT 2mg·L^-1 + KT 3mg·L^-1 obtained more shoot proliferation to 8.20 folds.4. The suitable medium for rooting of shoots was White + IBA 0.03mg·L^-1 + NAA 0.1mg·L^-1, with 50% rooting and 10 or more average root number. Rooted shoots were transplanted into artificial mixture （peat:vermiculite:perlite=1:1:1） whose survival rate was 80%.5. Use longitudinal grafting method to graft adult shoot tip scion onto middle of juvenile seedling rootstocks in vitro and in vivo. Both of graftings attained high survival rate, but the scion growth dropped as repeated twice in vitro, while the scion rejuvenated in in vivo practice after repeated grafting for three times.6. HPLC results showed that juvenile shoots and adult shoots have different DNA methylation level. The degree of methylation of 1 year old shoot was more than 18 years old, and that of 18 years old shoots was more than 80 years old. Repeated grafting shoots enabled to induce more methylation compared to adult shoots.