| Chrysanthemum (Dendranthema grandiflorum) which originated in China, is one of the ten traditional famous flowers in China and the top one of the four cut flowers in the world. Chrysanthemums have vital status in autumn garden greening in northern China and environment beautify. Many cities in China will hold chrysanthemum Shows in each autumn while it's not enough because of the late flowering of the most part of famous species. In order to improve the situation, better species are needed, and the traditional breeding technologies are unhelpful. As a new breeding method, transgenetic technology is helpful on changing flower colours, types, florescence, light sensitivity and pest resistance. Besides, it also expands chrysanthemum breeding methods and speeds up breeding process. It is meaningful on new chrysanthemum species improvement and cultivation. However a successful genetic transformation should based on efficient regeneration systems and required certain regeneration frequency and propagation coefficient. In order to establish a stable and repetitive chrysanthemum regeneration system, we seted up a series of studies which included the following three parts.1. Establishment of chrysanthemum efficient adventitious buds regeneration system"Wan shuhong", "Fen juhua", "Huang jinqiu" were the three initial choices in our test, but the latter two showed low regeneration frequency and serious browning, at last "Wan shuhong" became the only reseach object. In the "Wan shuhong" regeneration system, the use of aseptic leaves directly for the explant tissue, not only reduced pollution but also improved the regeneration rate. In the 30 sets of adventitious buds direct induction mediums, the formula of MS+6-BA0.5 mg/L+NAA2.0 mg/L reached 83.3%, the highest rate of adventitious buds. In a certain range, shoot regeneration rate increased with the increase of NAA concentrations, while decreased with the increase of 6-BA concentration. During the process of propagation of plants in vitro,1/2 MS medium was chosen as the optimal one; 1/2 MS+NAA 0.1 mg/L was chosen as rooting medium.2. Study of chrysanthemum Vitrification reversionVitrification is a common phenomenon in the process of tissue culture, which must be prevent for bad affects of growth and rooting of plantlets. Vitrification is a result of multiple effects and vitrification seedings could be caused by any inappropriate factor during experiment. In this section we observed the reversion results by changing the concentration and status of seven factors which affected most to vitrification seedings. Except aggravating in dark culture, vitrification was more or less reversed, of which by changing the concentration of sucrose, agar and hormone. In our experiment, we increased sucrose concentration to 40 g/L, increased agar concentration to 8.5 g/L and reduced the hormone concentration to 1/4 of the original medium, the results reached the highest reversion rate compared with each similar treatment, they were 26.67%,30%,40% respectively. Because of the complexity of reasons, vitrification can not be completely eliminated by adopting one or few ways except prevention and reversion at the same time.3. RAPD analysis during different chrysanthemum speciesWe analysed the genetic diversity and genetic relationship of 10 chrysanthemum species by RAPD technique, and make out cluster analysis according to their similarity and divergence. Among the 10 species, "Wan shuhong", "Fen juhua", "Huang helou"and "Xiao baiju" appeared divergence bands. Data analysis software NTSYS 2.0 was adopted and the results showed that "Fen juhua" and "Xiao baiju" had the closest relationship while others poor.
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