An efficient transformation method for tannin-containing sorghum

BACKGROUND: Tannins are the main bottlenecks restricting the transformation efficiency of plants. Hongyingzi is a special tannin-containing sorghum cultivar used in brewing. METHODS: In this study, a highly efficient microprojectile transformation system for tannin-containing sorghum was successfully exploited using immature embryos (IEs) of Hongyingzi as explants. RESULTS: Hongyingzi presented two types of calli. Type II calli were found to be the most suitable and effective explants for transformation. After optimization of the geneticin (G418) concentration and tissue culture medium, an average transformation frequency of 27% was achieved. Molecular analyzis showed that all transgenic plants were positive and showed transgenes expression. The inheritance analyzis confirmed that the transgenes could be inherited into the next generation. Thus, we successfully established an efficient transformation system for tannin-containing sorghum and demonstrated the possibility of breaking the restriction imposed by tannins in plants.