Establishment of Genetic Transformation System of Non-Embryogenic Callus in Rosa rugosa

Rosa rugosa (R. rugosa) is a commercially important ornamental species within the genus Rosa, highly valued in the horticultural market. With the increasing availability and improved annotation of Rosa genomes, establishing an efficient genetic transformation system has become essential for validating candidate gene functions. As a common intermediate tissue in plant regeneration, callus has been successfully used to establish genetic transformation systems in numerous species. In this study, we characterized the morphological and physiological differences between embryogenic and non-embryogenic calli in R. rugosa. The embryogenic callus exhibited significantly higher catalase (CAT) activity and proline (PRO) content than the non-embryogenic callus. However, its growth rate was markedly slower. Antibiotic sensitivity assays identified the optimal selection concentrations for non-embryogenic callus as 35 mg/L for kanamycin and 13 mg/L for hygromycin. We subsequently introduced the phytoene synthase (RrPSY1) gene into non-embryogenic callus, with positive transformants identified using GFP fluorescence detection and PCR analysis. The overexpression of RrPSY1 significantly increased the yellow pigment substances in the callus, confirming the establishment of an effective genetic transformation system for non-embryogenic calli in R. rugosa. This system provides a useful technical platform for the manipulation of metabolic products and the verification of related gene functions in rose.