Induction Of Embryogenic Callus And Suspension Culture Of Tissue Culture Seedlings Of Fraxinus Mandshurica Rupr.

Fraxinus mandshurica Rupr.is an important economic crop of Oleaceae,Fraxinus.Fraxinus mandshurica has high value in use,which is a famous wood used for military and high-grade material of furniture making.However,the resources of this species have always been very poor and it has been classified as a vulnerable species.It mainly breeds by seeds,and can also by cottage or sprouting regeneration.Fraxinus mandshurica is one of the slow-growing species.Therefore,tissue culture techniques can be used to breed this species.Studies have shown that,it is difficult to breed the Fraxinus mandshurica by the callus regeneration.Therefore,based on the relevant academic literature,by screening the culture conditions for different explants of Fraxinus mandshurica,we would identify the conditions which will induce the embryonic callus of Fraxinus Zandshurica,and establish a suspension culture system for the embryonic callus of Fraxinus mandshurica,that we could lay the foundation for inducing somatic embryos of Fraxinus mandshurica by single cell culture in the future.At the same time,this paper attempts to breed Fraxinus mandshurica tissue culture seedlings in different culture methods;select preliminary the suitable culture mode for tissue cult'ure seedlings of Fraxinus mandshurica,which will provide the base for optimization experiment and large-scale breeding later.Based on above research,the conclusions are as follows:1.The embryonic callus induction conditions of Fraxinus mandshurica have been screened out and a suspension culture system has been established:Leaves or petioles were used as explants,WPM as the basic medium,adding 0.1 mg/L NAA,0.5 mg/L IB A,1.5 mg/L 6-BA?0.3 mg/L TDZ,30 g/L sucrose,5.6 g/L agar.With 1?2 generation in light,the callus could be obtained,which is loose and like embryonic.When using the same medium to proceed liquid suspension culture,2 g/50 mL inoculation and 120 r/min for 18 days,the growth amount could reach the highest,about up to 500%.Using the microspore of Fraxinus mandshurica as the explants,the cell masses similar to somatic embryos were obtained.2.The breeding method of tissue culture seedlings of Fraxinus mandshurica has been initially established:liquid immersion culture with WPM,the basic medium,2.0 mg/L 6-BA.0.15 mg/L NAA,20 g/L sucrose is beneficial for the germination of terminal and lateral bud of tissue culture seedlings of Fraxinus mandshurica.3.The effects of increasing nitrogen and phosphorus concentrations on the proliferation of embtyonic cells and the propagation of tissue cultured seedlings were investigated.The excess of nitrogen and phosphorus inhibited the growth of embryonic cells of Fraxinus mandshurica,but prompted the terminal buds of Fraxinus mandshurica elongation,800 mg/L KNO3 or 170 mg/L KH2PO4 could promote the elongation of the terminal bud.