Establishing an efficient callus genetic transformation system for the tung tree (Vernicia fordii)

Tung tree (Vernicia fordii) as an important industrial raw material used to produce tung oil in China. Genetic transformation system has not been established for the tung tree, hindering research on the functions of tung tree genes and the cultivation of new stress-resistant varieties. In this study, we optimized the tissue culture regeneration system of tung tree hypocotyls, screened out a callus state suitable for Agrobacterium tumefaciens infection, and improved the efficiency of genetic transformation. RNA interference (RNAi) vector was constructed using FAD2 as the target gene. Adventitious shoots were obtained by infecting the hypocotyl calli cultured for 25 days through Agrobacterium-mediated infection. The positive adventitious shoot transformation rate of the pBI121 vector was 22.86%, and the adventitious shoot transformation rate of the RNAi vector was 7.84%. We established a complete genetic transformation system using two vectors, and the system was verified via GUS staining and real-time fluorescence quantitative analyses to ensure its stability. This system solves the technical problem of a genetic transformation system for the tung tree, and will provide technical support for studying the functions of tung tree genes and molecular breeding.