A combined culture system for leaf explants of Lycium ruthenicum with high genetic transformation rates and low seedling vitrification rate

[Objective] We aim to establish an efficient and stable genetic transformation system of Lycium ruthenicum and reduce the vitrification rate of the regenerated seedlings in order to promote gene function study and genetic improvement. [Methods] L. ruthenicum leaves were used as explants and Agrobacterium (LBA4404, EHA105) was used to transform L. ruthenicum. By adjusting the types of basic medium and adding plant hormones, we selected the optimal callus-induction medium, differentiation and selection medium, and rooting-induction medium. The transformation rate of L. ruthenicum was increased to over 65%, while the seedling vitrification rate was decreased to below 10%. This combined culture system laid a foundation for the molecular breeding of L. ruthenicum. [Results] (1) The optimal infection concentration of Agrobacterium (OD600) was 0.6 and the infection time was 25 min for the combined culture system of L. ruthenicum. Under this condition, the callus-induction rate was 78.2%-96%; (2) The optimal differen