Studies On Regeneration System Of Leaf In Vitro In Heading Chinese Cabbage

Four heading Chinese cabbage'06J28','92S105','06J30'and'06J31'provided by Chinese cabbage research team of Northwest A&F University were used as the experiment materials in this study. Investigation was carried out on the effects of the leaf adventitious shoot regeneration. The factors included the hormones ratio, the different modes of explant cutting and inserting, silver nitrate and different basic mediums and so on. The histological texture change of adventitious shoot occurring was observed also. The resurts are as follows:1. The leaf high frequency of in vitro regeneration system in heading Chinese cabbage was established. The first leaf of heading Chinese cabbage seedling which just emerge second leaf were used as experiment materials. First, transect at the junction of petioles and the hypocotyls and keep the first intact leaf as the explants, then put the petiole's end straight down into MS + 4.0 mg·L^-1 6-BA + 0.14 mg·L^-1 NAA medium and culture for about 12 days. When the explant regenerate adventitious shoot, it was transferred into MS + 4.0 mg·L^-16-BA + 0.14 mg·L^-1 NAA medium to rejuvenate the adventitious shoot for about 10 days , then transplanted into the 1/2MS + 1.0 mg·L^-1 IBA medium for rooting. The culture conditions was temperature of 25±1℃, the lighting time 16 h/d, light intensity for 40 mmol·m-2·s^-1.2. Under the above regeneration system, the four materials all obtain adventitious shoots with leaf as explant. Among them,'06J28'get the best regeneration rate and regeneration coefficient which reached as high as 87.63% and 2.62 respectively, and its rooting rate is 70%,'92S105'has a highest regeneration coefficient -3.76.3. The regeneration rate and regeneration coefficient of'06J28'were 80.73% and 1.89 respectively in the MS medium supplemented with 0.3 mg·L^-1 TDZ and 0.14 mg·L^-1 NAA, which meant that TDZ has similar effect to 6-BA;4. Add different concentrations of AgNO3 into MS + 4.0 mg.L^-16-BA + 0.14 mg.L^-1NAA optimal shoot induction medium. The results shown that low concentration (less than 8.0 mg·L^-1) has no effect on adventitious shoot regeneration, while high concentration (10.0 mg·L^-1) has inhibitory action to adventitious shoot regeneration;5. In the same hormone conditions, there were no significant differences for heading Chinese cabbage leaf adventitious shoot regeneration between self-prepared MS medium and MS powder-made medium, both satisfy the requirements of experiments. 6. Histological observation shows that'06J28'leaf adventitious shoot regeneration is from the parenchyma cells around the vascular bundles of the leaf petiole cutting which started spilt, formed plentiful meristematic cells mass and then became callus at the middle of the cutting end. The surface of callus got further exuberant split, becoming bud primordium and leaf primordium, and then continue growing to form adventitious shoots.