Conservation And Regeneration Of Potato Callus In Vitro

Potato is one of the most important food and vegetable economic crops in the world,and plays an important role in the national economy.Establishment of the regeneration system of potato provides a foundation for many other researches, especially the transgenic technique developed in recent years,which depends on an efficient regeneration system.Potato is one of the vegetative plants and the traditional conservation not only needs labor and money very much,but also is affected by diseases and insect pests,natural disasters.In vitro conservation has become the important complementary conservation technique for its advantages of economy,safety and saving room and money.Based on pre-researches,further studies were carried out on potato culture and germplasm conservation in vitro.The major results are as follows:1.The optimal medium for callus induction from leaf and stem of potato variety Atlantic were MS+6-BA 2.5mg/L+NAA 0.3mg/L and MS+6-BA 2.5mg/L+NAA 0.2mg/L respectively,the callus induction rates all reached up to 100%.The optimal medium for adventitious bud differentiation from leaf-derived callus and stem segment-derived callus was found to be MS+6-BA 3.0mg/L+NAA 0.1 mg/L+GA₃ 5.0mg/L,MS+6-BA 2.0mg/L+NAA 0.05mg/L+GA₃ 5.0mg/L respectively.The adventitious bud differentiation rate reached to 100%and 80%respectively.The optimal medium for rooting induction from tube plantlets was 1/2 MS+NAA 0.2mg/L and the rooting rate was 100%.The survival rate of tube plantlets after transplantation was 91%.2.The physiological and biochemical changes have been studied during conservation of potato callus in vitro in normal temperature and low temperature.The results showed that the survival rate,differentiation rate,TTC value and SOD viability in treated and controlled were decreased during the conservation,but the treated were higher obviously;The contents of MDA and the electrolyte leakage rate were increased during the conservation,but the treated were lower obviously;The POD viability,the contents of the Pro and soluble carbohydrate were increased firstly,and then decreased, the treated were lower than controlled in the POD viability but the contents of the Pro and soluable carbohydrate were higher obviously.3.Callus of Potato was successfully cryopreserved with the vitrification technique. A suitable procedure was established as follows:Callus induced about 20d was precultured on MS medium with 0.4mol/L sucrose for 2d.Dissected callus about 2.5×2.5mm² was loaded with 60%PVS2 for 20～30min at room temperature,and was exposed to PVS₂ at 0℃for 50 min.Followed by changing the solution with fresh PVS₂, the callus was immersed into LN directly,and kept for 24h.After rapid thawing in a water bath at 40℃,the callus was washed with 1.2mol/L sucrose solutions for twice (each time 10min) and transferred onto the regeneration medium.The cultures were kept in dark for one week prior to exposure to the light.The survival rate of callus reaches 57.5%.The differentiation rate of bud induced from the callus cryopreserved by vitrification was 36.36%and the bud could develop normally and no difference was found in morphology.