| In this experiment the seeds and stem segments were used as explants for in vitro culture and conservation materials of peach and pear germplasm.The main contents of the experiment were as follows: establishment of the high-effeciency in vitro regeneration system of peach and pear; In vitro conservations included restricting growth methods built on plant tissue culture and changes of trace elements on STN(shoot-tip necrosis) and normal seedlings in the in vitro culture of peach embryo seedings and so on, which provided materials for the conservation and establishment of in vitro regeneration system of peach and pear. The main results were described as follows:1. Establishment of the regeneration system of peach. The experimental results showed that the effective method of surface sterilization for the seeds of peach was treated with 75 % alcohol for 15 s, 0.1 %HgCl2 for 5 min, and sterile water for 24 h as well as 0.1 %HgCl2 for 3 min. The best methord for in vitro germination was to remove the endopleura of peach seeds. G+6-BA0.5 mg·L-1 + IBA0.2 mg·L-1 was favorable to the proliferation of buds.The best seasons for the stem segments was from September to October, and MS+ 6-BA1.0 mg·L-1 NAA0.01 mg·L-1 was the superior medium for multiple shoot induction of peach.2. The in vitro culture of embryos and in vitro conservation of peach. The experimental results showed that the shoot-tip necrosis was popular in different peach cultivars. The descending ordinal rate of shoot-tip necrosis was cultured on the medium G, MS, and B5 and then White.The appropriately variable temperature or low temperature could reduce or eliminate the shoot-tip necrosis, low concentration of 6-BA and GA3 could reduce or eliminate the shoot-tip necrosis and the shoot-tip necrosis rate increased where the concentration increased. Rooting could extended conservation time of peach in vitro, and G+KT0.5 mg·L-1+IBA0.2 mg·L-1+30 g·L-1sucrose+ 6 g·L-1 was the best medium for conservation of peach in vitro.3. Analysis on the differences of the trace element contents between normal seedlings and shoot-tip necrosis seedlings in peach. Experiment results indicated by flame atomic absorption spectrometer showed on the in vitro culture conditions, the iron content of shoot-tip necrosis seedlings was less than that of normal seedling leaves, Cr content was higher than that of the latter, and on the in vitro conditions Mn content of shoot-tip necrosis seedlings was less than that of normal outdoor seedling leaves, and Cu and Zn content was higher than that of the latter, and on the in vitro conditions Cu and Zn content of shoot-tip necrosis seedlings was less than that of non-germinated seed leaves,while the Cr content was higher than that of the latter.4. Establishment of the regeneration system of pear. The experimental results showed that seed germination in vitro required removal of the endopleura of pear, the best medium for germination was MS+ 30 g·L-1 sucrose + 6 g·L-1 agar, whose germination rate was86.67 %, The best proliferation medium was MS+ 6-BA0.5mg·L-1+ IBA0.1 mg·L-1 + sucrose 30 g·L-1+ agar 6 g·L-1, whose multiplication coefficient was 3.12, the best medium for rooting was 1 / 4 MS + NAA0.3 mg·L-1 + IBA0 mg·L-1 + sucrose 30 g·L-1 + agar 6 g·L-1, whose rooting rate of 63.26 %; The most superior rooting medium was 1/2 MS +NAA0 mg·L-1 + IBA0.4 mg·L-1 sucrose 30 g·L-1 + agar 6 g·L-1, where the average root number was 4.125 per plantlet.5. Technique programs of germplasm conservation system of pear in vitro were established. The comparisons of the effects of the different conserved conditions such as 500 lx of illumination, adding 3 g·L-1 active carbon in the medium, and reducing 3/4 of the macro elements, adding 10-15mg/·L-1 PP333 in the medium,10 g·L-1L agar and 30 g·L-1 warte in the medium, and adding 8g·L-1 agar in the medium, adding 60 g·L-1 mannitol in medium, adding 0.5 mg·L-1 ABA in the medium and so on, on the conservation,were conducted, and the experimental results showed the pear plantlets were conserved for over 6 months at the survival rate of 95% under the best condition.
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