Abstract: In this study, the leaves and petioles of eight varieties of Viola × wittrochiana were used as explants to screen and identify the varieties and tissues of the highest regeneration rates. Subsequently, the petioles of the PXP were chosen as explants to optimize the regeneration system, thereby establishing a complete plant regeneration protocol for V. × wittrochiana. This protocol aimed to provide a technical system for rapid propagation and genetic improvement of V. × wittrochiana. The results indicated that PXP was the optimal variety and petioles were the optimal explants for establishing the regeneration system. The optimal medium for callus induction was 1/2MS (sugar-free)+30 g∙L–1 sucrose+1.5 mg∙L–1 2,4-D+1.5 mg∙L–1 KT. The optimal medium for adventitious shoot induction was 1/2MS (sugar-free)+30 g∙L–1 trehalose+0.05 mg∙L–1 2,4-D+3 mg∙L–1 6-BA. Repeate induction could promote the regeneration rate of shoot differentiation to 67.33%±3.06%. The optimal medium for adventitious shoot proliferation was MS (sugar-free)+30 g∙L–1 trehalose+0.5 mg∙L–1 2,4-D+1 mg∙L–1 6-BA, with a proliferation coefficient of 3.29±0.22. Regenerated shoots began rooting after two weeks on rooting medium consisting of 1/2MS (sugar-free)+30 g∙L–1 trehalose+0.1 mg∙L–1 NAA, with a rooting rate of 84.44%±6.93%. This study addressed the challenges of adventitious shoot differentiation in V. × wittrochiana and established a regeneration system with high shoot differentiation rate, providing technical support for breeding and genetic improvement of the species.

Key words: Viola×wittrochiana, petiole, regeneration system, tissue culture, repeate induction