| Cunninghamia lanceolata Hook.is one of evergreen coniferous species,native to China.For its fast growth,the increasing wide uses and so on,it is popular with the masses.Based on using the excellent germplasm immature zygotic embryos as the initial explants for somatic embryogenesis research,by dint of 311-A regression Design,this thesis discussed various factors that affect somatic embryogenesis.And the physiological and biochemical differences were also analyzed in this thesis,with a view to establish efficient and stable system of somatic embryogenesis.The main experimental conclusions were as follows:(1)Both the ways of inoculation and preservation of the initial explants had an obvious effect on inducting callus.In this trial,the highest callus induction rate was up to 46%,which was by the way of cutting a small hole on the seed capsule,and the callus it induced was larger and of better quality.Refrigeration(4℃, one month)was also good for callus induction.(2)The genotypes of the initial explants had a mighty significant impact on inducing callus.Among all of the genotypes,the callus induction rate of Y21×S27 was the highest,which was 39.37%,while the rate of 5034×Y27 was the lowest,only 10.50%.(3)The callus induction rate had a close relationship with the growth stages of the initial explants,and it was improved with the maturity of the immature zygotic embryos.The rate of the cones picked on June 25th was the highest,up to 43.33%;secondly,the cones picked on July 2nd,up to 35.26%;the last was the cones picked on July 16th,only 15.51%.(4)Using 311-A Regression Design to analyze the effect of 2,4-D(x1),6-BA(x2)and KT(x3)on the callus induction rate,we established the polynomial regression equation between the callus induction rate and the three factors,as the following: y=0.0683+1.1711 * x1+3.2220 * x2+0.9528 * x3-0.0213 * x1 * x1-0.3313 * x2 * x2+0.0275 * x3 * x3+ 0.0240 * x1 * x3+0.0451 * x2 * x3(R2=0.9899) By analyzing the main and mutual effects,it comed to conclusion that the best medium was DCR+2,4-D 24 mg·L-1+6-BA 4 mg·L-1+KT 8 mg·L-1.The result was scientific as well as reasonable.(5)The concentration of inositol in culture medium has notable impact on the rate of callus multiplication. When the concentration of inositol varied from 1 g·L-1to 7 g·L-1,the rate was from 130.92%upgrading to 200.93%,but when it continued to increase,the multiplication rate dropped rapidly to below 0,instead.Even browning occurred.(6)The types and concentration of hormone played a vital role in callus multiplication.In this trial,the lower the concentration of 2,4-D was,the higher the multiplication rate was.When the concentration of 2,4-D was 0.6 g·L-1,the multiplication rate was up to 146.26%.While adding the NAA 0.6 g·L-1to the medium, the callus multiplication rate was only 97.37%,the effect was not so good as the former.(7)The content of GA3,IAA and ABA of immature zygotic embryos of different genotypes and growth stages were different,respectively.As a whole,the content of the three endogenous hormone increase along with the maturity of the immature zygotic embryos.Moreover,the study found out that it took on positive correlation between the induction rate and the content of both endogenous ABA and IAA in immature embryos. Their correlative coefficient were up to 0.57 and 0.78**,respectively.(8)The content of soluble sugar,soluble protein and the activity of antioxidant enzyme in embryogenic callus were all higher than those of non-embryogenic callus.The study also found out that adding the NAA (0.6 mg·L-1),ABA(0.5 mg·L-1)and inositol(7 g·L-1)to culture medium could remarkably increase the content of soluble protein and soluble sugar.Both NAA(0.6 mg·L-1)and ABA(0.5 mg·L-1)could stimulate the activity of SOD,POD,CAT.Different kinds of antioxidant enzymes responded to the osmotic stress of inositol, diversely.The activity of SOD increases along with the concentration of inositol advancing.So did POD.Both of them took on rise first then rapidly decline,showing the more severe stress,the lower activity.The activity of CAT,however,was opposite,showing the more severe stress,the higher activity.
|
PDF Full Text Request