Abstract: INTRODUCTION: Korla fragrant pear, a characteristic fruit tree of Xinjiang, faces significant challenges in genetic transformation, including protracted cycles, low efficiency, and labor-intensive procedures, which severely hinder its varietal improvement through genetic engineering. RATIONALE: In this study, we optimized the key parameters for an Agrobacterium-mediated non-tissue culture transformation system using buds of Korla fragrant pear trees. Factors such as bud developmental stage, infection solution composition, Agrobacterium concentration, and bud type were systematically evaluated. Through these optimizations, successful genetic transformation of Korla fragrant pear was achieved. RESULTS：The results indicated that the optimal conditions for the experimental genetic transformation included: a receptor bud stage of March 30, an infiltration solution of 10 mmol.L–1 MES, an Agrobacterium concentration of OD600= 0.8, and the use of lateral buds as the preferred explant type. In addition, this study targeted the PsHB12 gene, which is involved in ABA signaling and associated with overwintering cold tolerance. Overexpressed transgenic buds of PsHB12 were successfully obtained with a transformation efficiency of 25.27%, and quantitative analysis confirmed significantly higher PsHB12 transcript levels in transgenic buds compared to wild-type controls. CONCLUSION: This research provides an efficient genetic transformation approach for Korla fragrant pear and establishes a critical technical foundation for future functional characterization of cold-resistance genes and molecular breeding efforts.

Key words: Korla pear, agrobacterium-mediated, tree bud transformation method, psHB12