Abstract: INTRODUCTION: Prunus mume, a renowned traditional flower in China, plays a significant role in garden landscapes. However, conventional artificial hybridization breeding methods for P. mume face challenges such as lengthy breeding cycles and limited genetic variation. Therefore, establishing an efficient regeneration and genetic transformation system for P. mume is of great importance for its breeding advancement.  RATIONALE: To establish an efficient genetic transformation system for P. mume and lay a technical foundation for its genetic improvement, leaves from four cultivars (Zao Lve, Danfen Chuizhi, Xiang Ruibai, and Xiangxue Gongfen) were used as explants. Based on WPM medium, the effects of different types and concentrations of plant growth regulators on callus induction efficiency were systematically evaluated. Using callus derived from Xiang Ruibai, an Agrobacterium-mediated transformation method was applied to optimize three key parameters—bacterial suspension concentration, infection time, and co-cultivation time—and to assess their impacts on transformation efficiency. This study provides a foundation for establishing a complete and efficient genetic transformation system for P. mume.  RESULTS: The optimal callus induction medium and induction rates varied among different P. mume cultivars. For Zao Lve and Xiang Ruibai, the most effective medium was WPM supplemented with 1.0 mg∙L–1 6-BA, 1.0 mg∙L–1 TDZ, and 0.5 mg∙L–1 2,4-D, achieving induction rates of 61.70% and 66.67%, respectively. For Danfen Chuizhi, the best medium was WPM with 1.0 mg∙L–1 6-BA, 0.5 mg∙L–1 TDZ, and 0.3 mg∙L–1 2,4-D, resulting in an induction rate of 84.38%. For Xiangxue Gongfen, the optimal formulation was WPM containing 0.5 mg∙L–1 6-BA, 0.5 mg∙L–1 TDZ, and 1.0 mg∙L–1 2,4-D, which yielded an induction rate of 66.67%. In genetic transformation experiments using callus from Xiang Ruibai, the highest transformation efficiency (17.00%) was obtained under the following conditions: bacterial suspension OD600=0.7, infection time of 15 minutes, and co-cultivation period of 5 days.  CONCLUSION: This study systematically compared the hormone requirements of four P. mume cultivars, revealing significant cultivar-specific differences in callus induction. Based on these findings, the positive transgenic callus of Xiang Ruibai was successfully obtained. This provides a technical foundation for verifying gene functions and conducting genetic improvement of important traits in P. mume.

Key words: Prunus mume, callus tissue, genetic transformation