( 3 ) the optimal explant age for transformation was 6 or 7 day after aseptic germination of seeds . ( 4 ) development of non - transformated cell was inhibited completely by 100mg / l kan . ( 5 ) 500mg / l cb could avoid pollution of agrobacterium tumefaciens and had no distinct effects on the formation of callus and shoot regeneration . ( 6 ) the optimal co - cultural condition was 3 day on 28 in dark 以胡萝卜品种“改良黑田”为受体材料，以胡萝卜幼苗的下胚轴为外植体，建立了农杆菌介导法的胡萝卜转化体系，并对其中的种子消毒、激素水平、外植体的苗龄、选择压、共培养时间等关键步骤的条件进行了优化。
