PROBLEM TO BE SOLVED: To provide a method and a composition for improving the efficiency of bacterium-mediated plant cell transformation by using an additional transformation enhancer sequence such as overdrive or TSS sequences operably linked to the T-DNA border sequence on a recombinant construct that comprises T-DNA.SOLUTION: Provided is a method for improving the efficiency of Rhizobium bacterium-mediated plant cell transformation, comprising transforming a plant cell with a Rhizobium bacterium where the Rhizobium bacterium contains a plant transforming vector comprising at least one T-DNA border sequence derived from Agrobacterium tumefaciens and a specified transformation enhancer sequence operably linked to the T-DNA border sequence.SELECTED DRAWING: None【課題】T-DNAを含む組換え構築物上のT-DNAボーダー配列に作動可能に連結した、オーバードライブ又はTSS配列のような更なる形質転換エンハンサー配列の使用によって細菌－媒介植物細胞形質転換の効率を改善するための方法および組成物の提供。【解決手段】リゾビウム属細菌－媒介植物細胞形質転換の効率を増大させる方法であって、植物細胞をリゾビウム属細菌で形質転換し、該リゾビウム属細菌はアグロバクテリウム・ツメファシエンス（Agrobacterium tumefaciens）からの少なくとも１のT-DNAボーダー配列及び該T-DNAボーダー配列に作動可能に連結された形質転換エンハンサー配列を含む植物形質転換ベクターを含み、特定の形質転換エンハンサー配列を含む方法。【選択図】なし
