An optimized protocol for in vitro regeneration and genetic transformation of broomcorn millet

Background Broomcorn millet has many advantages, such as abiotic stress resistance, a short growth cycle and high nutritional value. However, due to the lack of efficient genetic transformation methods for broomcorn millet, the characterization of genes related to important traits lags behind that of other crop species. Therefore, establishing efficient in vitro regeneration and genetic transformation methods for broomcorn millet is essential. Results In this study, we used mature seeds from the sequenced cultivar 'Longmi 4' as explants and optimized their in vitro regeneration and genetic transformation methods. The optimal hormone concentrations for embryogenic callus induction medium were 2.5 mg/L 2,4-D and 0.5 mg/L BAP. The optimal hormone concentrations for shoot regeneration media were 2 mg/L kinetin and 0.5 mg/L a-naphthaleneacetic acid. Additionally, the cocultivation time was 3 days, and the optimal hygromcin concentration for putative transgenic callus selection was 45 mg/L. The transgenic efficiency was 21.25% after our modification approach. Conclusions Here, we present a simple and highly efficient Agrobacterium -mediated genetic transformation protocol for broomcorn millet. Our work provides a tool for the characterization of genes related to important traits, as well as a new strategy for broomcorn millet breeding.