Tissue Culture In Liriodendron Chinense And Its Physiological And Biochemical Characteristics During Plant Regeneration

Liriodendron chinense ( Hemsl. ) Sarg., a deciduous tree of Liriodendron in Magnoliaceae, which is considered as living fossil plant, it is an important tree for garden greening in China. Recently, with the improvement of the man to environment quality, the requirment of Liriodendron chinense is increasing year by year. The techniques, developed in 1970, for tissue culture provide the selection of resistant varieties with an advanced method. The range and frequency of somaclonal variation will be extended widely by combing these techniques with treatment of rational factors. The application of tissue culture becomes a highlight increasingly because of its easy operation as control, lower costs and short period of breeding. The efficient propagate route, the germplasm resources conservation and the theoretic foundation in popularizing the Liriodendron chinense should be provided by tissue culture.Taking wild Liriodendron chinense stemtip from E-Mei mountain as experimental material, then its tissue culture mass propagation was studied and selected the best sampling time for explant insertion and medium combination. The results didacated that It is the best time in May that explants are collected and the startup rate gets 81.93%. In iniastion culture, MS medium with 6-BA 1.0 mg /L and IBA 0.5mg/L, is the best iniastion medium of Liriodendron chinense to sprout to childhood. The best subculture proliferation medium is MS, 6-BA 1.0 mg/L, IBA 1.0mg/L and NAA 0.1mg/L combination, The multiplication rate of shoot clumps could reach 5.41. In rooting culture, 1/2MS medium with IBA 0.1mg/L, NAA 0.1mg/L and ABT 0.2mg/L is the best one in rooting culture. The rooting rate is 82.93%.In order to elucidate the mechanism of callus differnciation and understand the mechanism of organogenesis, physiological and biochemical change characteristics during the course of plant regeneration in Liriodendron chinense tissue culture. The experimental results show that O2.- content of Liriodendron chinense has significant difference between two treatment meathods of untransfered and transfered, and it variation trend can be described as decreasing firstly, then increasing and decreasing finally. The time is longer, the regeneration velocity is higher, too. There is a close relationship between H₂O₂ content and differentiation process. H₂O₂ maybe play an important effect during regeneration plantlet differentiation as signal transduction factor. With the CAT activity increases, the H₂O₂ content decreases, that is the CAT activity extrme higher, so the H₂O₂ content declines lower. MDA content decreases firstly,then increases during differentiation process. IAA oxidase activities decrease firstly,then increase during differentiation process. Regeneration plantlet differentiation process is controlled by IAA content controlling, the ratio of cytokinins and auxins through IAA oxidation. Soluble sugar content of Liriodendron chinense decreases during differentiation process of all. With the differentiation process and tissue time continuing, the PPO activities increases together, which could influence the differentiation speed and browning in medium happenning.