Brachypodium sylvaticum, a Model for Perennial Grasses: Transformation and Inbred Line Development

Perennial species offer significant advantages as crops including reduced erosion, lower energy inputs after the first year, deeper root systems that access more soil moisture and decreased fertilizer inputs due to the remobilization of nutrients at the end of the growing season. These advantages are particularly relevant for emerging biomass crops and it is projected that perennial grasses will be among the most important dedicated biomass crops. The advantages offered by perennial crops could also prove favorable for grain crops like wheat, sorghum and barley, especially under the dryer and more variable climate conditions projected for many grain producing regions. Thus, it would be useful to have a perennial model system to test biotechnological approaches to crop improvement and for fundamental research. The perennial grass Brachypodium sylvaticum is a candidate for such a model because it is diploid, has a small genome, is self-fertile, has a modest stature, and short generation time. Its close relationship to the annual model Brachypodium distachyon will facilitate comparative studies and allow researchers to leverage the resources developed for B. distachyon. Here we report on the development of a highly efficient Agrobacterium tumefaciens-mediated transformation system. On average, 74% of callus pieces co-cultivated with A. tumefaciens produce transgenic plants.  We also created 15 inbred lines and surveyed the genetic diversity of 22 accessions from the National Plant Germplasm System using SSR markers.