Abstract: Potato is an important tuber crop. Agrobacterium tumefaciens-mediated potato genetic transformation is an important gene engineering method to improve molecular breeding efficiency in potato. It is very important to get the best transformation system and transformation efficiency. Stem segments and microtuber discs from potato varieties of Gannongshu No.2, Favorita, Shepody and Atlantic were used as acceptor materials. The transformation system of Agrobacterium tumefaciens-mediated were analysis depend on differentiation rate and transformation efficiency. The transformation rate in S2 (MS; 6-BA 2.5 mg·L^-1, 2,4-D 0.6 mg·L^-1, Carb 400 mg·L^-1, Kan 50 mg·L^-1), M2 (MS; 6-BA 2.5 mg·L^-1, IAA 0.25 mg·L^-1, 2,4-D 0.25 mg·L^-1, Carb 400 mg·L^-1, Kan 50 mg·L^-1) medium of stem segments from Gannongshu No.2, Favorita andf Atlantic were significantly higher than other mediums. The stem segment of Favorita had higher transformation rate than microtuber discs of Favorita. The microtuber discs of Gannongshu No.2 and Shepody had higher transformation rate than stem segment of Gannongshu No.2 and Shepody, respectively. The results showed that the best callus-inducing rate potato stem segment was observed on medium S2. The optimum differentiation medium components of potato stem segment was M2. Favorita was suitable for stem segment transformation system, and Gannongshu No.2 and Shepody were suitable for microtuber discs transformation system. The different reasons between callus induction medium and differentiation medium were genotype difference in different varieties. Screening genetic transformation system should be carried out according to different varieties.

Key words: agrobacterium, genetic transformation, callus induction, differentiation transformation rate