“…Since then, the protocol has been optimized (107,109) and used routinely for transforming Physcomitrella and for transient gene expression assays (4, 41, 42, 46a, 47, 48, 52, 66, 79, 97, 101, 110, 119, 130, 131). Transient gene expression was also reported following biolistic delivery of DNA-coated microbeads into protonemal tissue (58,106), but this method seems to be less efficient than PEG-mediated transformation as there has been only one report of a transgenic strain produced this way (58). Genetic transformation of Physcomitrella using Agrobacterium-based methods has also been attempted without success in several laboratories (28,94,109).…”