Study On Establishing Of Efficient Regeneration System Of Toona Ciliate

Toona ciliata(Chinese mahogany),belonging to the Meliaceae family,is one of the precious wild plants protected by the national level II.In this paper,the elite seedlings of Toona ciliata were selected as the object,and different parts of the plant were selected to optimize callus induction,callus differentiation and rooting conditions,then a mature and efficient regeneration system was established to make it foundation of the genetic transformation system.The main results of this study are as follows:1.The treatment of the seeds with 7.5% sodium hypochlorite(NaClO)for 20 minutes had the best disinfection effect,the pollution rate was 5.33%,and the highest germination rate was 92.67%.2.The optimum medium for callus induction in cotyledon was: MS+0.3 mg/L 6-BA+0.5 mg/L KT+0.05 mg/L NAA,the callus induction rate up to 69.33%;the optimum medium for leaf callus induction was MS+3 mg/L 6-BA+1 mg/L KT+0.05 mg/L NAA,the callus induction rate up to 85.33%;hypocotyl callus induction optimum medium: MS+0.5 mg/L 6-BA+1 mg/L KT+0.1 mg /L IBA,the callus induction rate up to 68.67%.3.Different genotype explants callus induction effect is significant.In the optimum medium for cotyledon callus induction,the cotyledon callus induction rate of genotype ZY4 can be up to 100%,but the differentiation rate of cotyledons of genotype ZY1 is 0.In the optimum medium for leaf callus induction and the callus induction rate of Toona ciliata leaves is the lowest,3.33%,and the callus induction rate of genotype YP5 is the highest,up to 96.67%,and in the optimum medium for hypocotyl callus induction the callus induction rate of the hypocotyl of Toona ciliata with the genotype XPZ3 is the lowest 6.67%,The callus induction rate of XPZ4 was the highest,up to 96.67%.4.Light and different placement methods on Toona ciliata induction of different explants was significantly affected.Under the condition of 12 h light +12 h dark treatment,the callus induction rate of different explants was higher than that of 24 h dark treatment.The callus induction rates of cotyledons,leaves and hypocotyls were 53.33%,90.67% and 66.67%,respectively,and 69.33% and 89.33% callus induction rates of cotyledons and leaves near the culture medium.Hypocotyls can be cultured in a medium in a horizontal way,and 73.33% callus induction rate can be obtained.5.The optimal medium for the callus differentiation of cotyledons was MS+0.3 mg/L 6-BA+0.2 mg/L NAA through optimization of hormone ratio,the callus differentiation rate up to 57.78% The best medium for callus differentiation of leaves was MS+0.5 mg./L 6-BA+0.2 mg/L NAA,the callus differentiation rate up to 60.00%.The best medium for callus differentiation of hypocotyls was MS+0.3 mg/L 6-BA+0.2 mg/L NAA,the callus differentiation rate up to 48.89%.6.Half-strength MS with 0.1 mg/L NAA,1.5% sucrose(w/v)and 0.5% agar(w/v)was used for rotting.plantlets were transplanted to sterilized nutrient soil containing vermiculite at a 2:1 ratio.Using this mixture,the 20-day survival rate was at 88.89%.7.Observing the entire process of leaf formation from callus to differentiation,first dedifferentiation of parenchyma cells from leaf wounds to form embryogenic callus;afterwards,the callus begins to differentiate and grow to form a bud;subsequent,the cell division of the bud site develops gradually become adventive buds.