Studies On Adventitious Shoot Regeneration From Leaf Pieces In Vitro And Genetic Transformation Of Apple

Apple (Malus × dome stica Borkh. ) scion cultivars 'New Jonagold ' , 'Royal Gala', 'Fuji' and rootstock clone 'M 26'were chosen as the materials. Several factors that affect the adventitious shoot regeneration from leaf pieces in vitro and Agrobacterium-mediated genetic transformation of apple were examined. The adventitious shoot regeneration system and genetic transformation system of apple with high efficiency were developed, and trans-genic plants of apple cultivar 'New Jonagold' were obtained.The main research results were as follows:1. MS medium is the suitable basal medium. No effect on regeneration efficiency of leaf pieces was found by substituting equal concentration (W/V %) glucose for sucrose in MS medium , while replacing sucrose with sorbitol greatly reduced regeneration efficiency. It was necessary for the shoot regeneration from leaf pieces of apple to supplement cytokinin in the regeneration media. It was not necessary for the regeneration to supplement auxin-like substance in the regeneration media, but addition of IAA,IBA or NAA(0.1 1.0mg L^-1) in the media significantly enhanced the regeneration efficiency of leaf pieces. TDZ was a potent exogenous cytokinin for the shoot regeneration from leaf pieces of apple. Compared to BA , TDZ showed three ad vantages: high cytokinin activity, wide effective range of activity, reducing the effect of physiology and biochemical status of leaf pieces before incubation on regeneration efficiency. The regeneration efficiency of leaf pieces of apple cultivar 'New Jonagold' was enhanced significantly by using in turn regeneration media supplemented with TDZ and BA respectively, however, the regeneration efficiency did not show accumulate or synergistic effect when the leaf pieces were incubated on the medium supplemented with TDZ and BA at the same time.2. Dark incubation was not necessary for adventitious shoot regeneration from leaf pieces. But a dark interval of 2³ weeks at the begining of regeneration significantly enhanced the regeneration efficiency of leaf pieces of apple3. Cefotaxime (200³00mg L^-1)in the regeneration media had no opposite effect on...