A simplified protocol for genetic transformation of switchgrass (Panicum virgatum L.)

The increasing interest in renewable energy has attracted more research attention on biofuels. In order to generate sustainable amount of biomass feedstock from dedicated biofuel crops such as switchgrass they need to be genetically improved. Genetic transformation is one of the techniques to achieve this goal. The aim of our study was to devise a simplified protocol for switchgrass genetic transformation. We have used NB0 as the basal medium and mature seeds of the cultivar Alamo as the starting material. The nutrient medium used and scutellum-derived callus are fashioned after rice genetic transformation protocols. We obtained friable calluses, which were similar to the type II calluses in other monocotyledonous species. Calluses were amenable for Agrobacterium-mediated genetic transformation with at least 6 % transformation efficiency. The concentration of hygromycin was optimized for successful selection of transgenic calluses. The Green Fluorescent Protein gene was used to monitor and demonstrate successful genetic transformation. Compared to the previously published methods for genetic transformation of switchgrass, our protocol is simpler and equally efficient. An efficient, simplified switchgrass genetic transformation method with NB0 basal medium and mature seeds as inoculum was developed. The appropriate concentrations of hormones and selection agent are described.