Tissue Cultue Of Old Platucladus Orientalis And Determination Of Nitrate Reductsae Activity

Arborvitae (Platyciadus orientalis (L.) Franco) belongs to cupressaceae arborvitae(Platycladus), and it is single species. It natives to the north and northwest of our country, andit’s the most widely distributed conifer in China. Because of the characteristics of resistanceto drought and barren, arborvitae has always been the pioneer species of afforestation onbarren hills in the north of China, and it’s also the important species of landscaping.There are more than82000ancient arborvitaes grow in the mausoleum of the YellowEmperor in Shaanxi province, and the age of more than30000trees over one thousand years,which is largest group of ancient arborvitaes in China. At present, because of old aging, root’scapacity to absorb water and nutrients can’t meet the needs of the growth, coupled with avariety of factors from outside, all above lead to different levels of erosion. Used in thisarticle the experimental materials taken from about3000years old ancient arborvitae in themausoleum of yellow emperor, the tree has entered a stage of old aging, and the seed cangrow but cannot retain full excellent characters, and tissue culture is not limited by season,number of materials, etc, and it can keep all excellent characters of ancient arborvitae,maintain its endangered germplasm resources, and it also has important reference value forthe propagation and the protection of ancient excellent germplasm resources. The mainresults were as follows:1. Research of stems’ tissue cultureUsed the young scale leaf taken from about3000years old ancient arborvitae in themausoleum of yellow emperor as explants in tissue culture research, draw the conclusion: it isbest to select young stems without wooden part from the old ancient arborvitae in April, afterpretreatment,75%alcohol12min30s+0.1%mercuric chloride+sterile water flushing3~4times. Auxin NAA, cytokinin6-BA and coconut milk plays an important role in the wholeprocess of tissue culture, but NAA and6-BA combine with other hormones (KT, GA3,2,4-D)only make small or non-existent effect. The optimal medium for initial culture is1/2MS+NAA0.1mg/L+6-BA0.2mg/L+coconut milk100mL, survival rate is42.6%; Theoptimal medium for sub-culture is1/4MS+NAA0.1mg/L+6-BA0.2,0.4mg/L+coconut milk200mL; Rooting experiment,1/2WPM basic culture medium, Two-step for rooting, activated carbon and dark culture are negative effects on tissue culture of the ancientarborvitae, NAA and IBA combination of regeneration bud rooting has certain effect.2. Research of the explants recovery from weakening after sub-culture:Explants appear to weaken and browning after more than three times subculture. Thenthe salt concentration of the medium was reduced to1/4MS, agar to6g/L, and each hormoneconcentrations should not exceed0.4mg/L. Coconut milk was increased to150mL.3. Study of nitrate reductase activityThis experiment used three age gradient arborvitaes (born in3000,30~40years and3~5years) as the research objects, measured the changes of nitrate reductase activity before andafter their tissue cultures. This experiment shows that tissue culture can promote the nitratereductase activity of arborvitaes in different ages，the ascensional range increases with ages,and the nitrate reductase activity of ancient arborvitae can recover to the condition of youngertree.