Optimization Of Rapid Propagation System Of Dendrobium Candidum

Dendrobium officinale Kimura et Migo is a perennial herbaceous plants,also known as Huangcao.It is distributed very rare in Chinese,which also the second class national protected and valuable medicinal herbs.D.officinale contains polysaccharide,amino acid,alkaloids,trace elements and other nutrients.In general,it plays physiological functions in antitumorigenesis and enhancing immunity.At present,the market supply and demand of D.officinale is severely imbalanced and production still can’t meet the market demand,and higher production costs.In this article,the suspension culture of D.officinale was studied,using D.officinale seeds and stem as explants,the optimum culture medium of each tissue culture stage was screened,and an efficient rapid propagation system was establishmented.The main results were as follows:1.With D.officinale stem segments as explants,establish a complete set of D.officinale asexual propagation system.The stem segments were used as explants to induce axillary buds.Design orthogonal test,the optimal medium was selected from the nine inducting media: 1/2 MS+1.5 mg/L 6-BA+0.5 mg/L NAA+70 g/L potato+25 g/L agar+ 6.5 g/L sucrose +1 g/L active carbon,the axillary bud induction rate was 54.1%.The optimal rooting medium was: N6+0.5 mg/L NAA+50 g/L potato +30 g/L agar+6.5 g/L sucrose +1 g/L active carbon,rooting rate was 93%.2.Selected optimal medium of efficient induction on protocorm.D.officinale seeds as explants,after 30 days germination on MS medium,protocorms growed with diameter of 0.473 mm-0.567 mm.After 30 days germination in the liquid medium,protocorms growed with diameter of 0.478 mm-0.956 mm.Using diameter of protocorms as the evaluation index,the optimal medium was: 1/2 MS+0.5 mg/L NAA+30 g/L agar.Protocorms could growed with diameter of 0.956 mm under the optimal medium.The size of the protocorms germinated in liquid medium was significantly larger than that of the solid medium.3.Selected optimal medium of rapid propagation system on protocorms.The seeds were germinated in MS solid medium for 30 days.A part of,the protocorms still inoculated on solid culture for 90 days.The results of orthogonal experiments show that: the optimal medium was: N6+NH4+/NO3-5:25+0.3 mg/L 6-BA+0.8 mg/L NAA+30 g/L agar+6.5 g/L sucrose +1g/L active carbon,taking the fresh weight of seedlings as the evaluation index.On the optimal medium,the maximum biomass of protocorms was 0.3 g fresh weight / bottle.Taking the seedling rooting rate as the evaluation index,the optimal medium was: Kc +NH4+/NO3-5:25+ 0.5 mg/L 6-BA+0.6 mg/L NAA+30 g/L agar+6.5 g/L sucrose+1 g/L active carbon.The maximum rooting rate was 50.9%.The 90 days seedlings were collected then dried,the crude polysaccharide was isolated and the content was 27%.Another part,the protocorms were inoculated in liquid medium for 30 days,the results of orthogonal experiments show that: taking multiplication rate of protocorms as the evaluation index,the optimal medium was: 1/2MS+ NH4+/NO3-5:25+0.1mg/L 6-BA+0.4mg/LNAA+30g/Lagar,the multiplication rate achieved 6.73.The protocorms were inoculated on solid medium after suspension culture.The results of orthogonal experiments show that,taking seedling height as the evaluation index,the optimal medium was: N6+0.2 mg/L 6-BA+0.6 mg/L NAA+50 g/L potato+25 g/L agar+6.5 g/L sucrose +1 g/L active carbon.The maximum seedling height achieved 1.74 mm.Taking the fresh weight of seedlings as the evaluation index,the optimum medium was: N6+0.1 mg/L 6-BA+0.4 mg/L NAA+100 g/L potato+25 g/Lagar+6.5 g/L sucrose +1 g/L active carbon.The maximum biomass of seedlings was 4.07 g fresh weight / bottle.Taking the seedling rooting rate as the evaluation index,the optimal rooting medium was: 1/2 MS+0.3 mg/L6-BA+0.6 mg/L NAA + 100g/L potato +25 g/L agar + 6.5 g/L sucrose + 1 g/L active carbon.The maximum rooting rate was 93%.The 90 days seedlings were collected then dried,the crude polysaccharide was isolated and the content was 30%.