There are a number of well-developed Agrobacterium-mediated transformation methods for dicotyledonous plants, but few for monocotyledonous plants. Fursova et al. develop a new approach for transient gene expression in the grass, Brachypodium distachyon, using co-cultivation of mature seeds with bacterial cells, and including leaf extract of Nicotiana tabacum and acetosyringone. Expressed proteins are directed to a plant apoplast, where they maintain hydrolytic activity and alter cell wall composition and biomass digestibility. This newly developed approach provides a quick and efficient technique for expressing genes of interest in Brachypodium.