An Agrobacterium tumefaciens transformation protocol effective on a variety of cottonwood hybrids (genus Populus)

 We describe a protocol for Agrobacterium tumefaciens-mediated transformation of hybrid cottonwoods (Populus sections Tacamahaca Spach. and Aigeiros Duby). The protocol has allowed routine transformation of several economically important cottonwood hybrids (Populus trichocarpa Torr. & Gray×P. deltoides Bartr. ex. Marsh. and P. deltoides×P. nigra L.) that were previously difficult to transform. The procedure was applied to 11 different hybrid cottonwood genotypes and one P. deltoides genotype using kanamycin as the selection agent. Additional experiments showed a very strong interaction between auxin preculture and the effectiveness of various cytokinins for induction of shoot organogenesis. The data also demonstrated the superiority of Agrobacterium strain EHA105 over C58 and LBA4404 for T-DNA transfer based on transient assays with a reporter gene. Received: 16 June 1998 / Revision received: 5 February 1999 / Accepted: 14 April 1999