Agrobacterium-mediated transformation of the wetland monocot Typha latifolia L. (Broadleaf cattail)

An Agrobacterium-mediated model transformation system was standardized for the wetland monocot Typha latifolia L. to achieve the long-term objective of introducing candidate genes for phytoremediation. Two binary plasmid vectors, pCAMBIA1301/EHA105 and pTOK233/LBA4404, both containing the gus (beta-glucuronidase) and hptII (hygromycin phosphotransferase II) genes, were used for transformation. Fifty-day-old 5 mg/l picloram-derived calli were cocultivated and selected on medium containing 20 mg/l or 40 mg/l hygromycin. Resistant calli were regenerated on medium supplemented with 5 mg/l 6-benzylaminopurine, with or without 20 mg/l or 40 mg/l hygromycin and with or without charcoal (10 g/l). Transient GUS activity in explants ranged between 28% and 36%. Hygromycin-resistant calli, selected after 3 months, showed stable GUS expression. A total of 46 plants were regenerated and established in the greenhouse; 13 showed stable GUS expression. Cocultivation of dark culture-derived calli, directly selected on regeneration medium containing 20 mg/l hygromycin and rooted on medium with 20 mg/l hygromycin was the best protocol. The addition of charcoal did not have any effect on regeneration. PCR and Southern analyses of transgenic calli and transgenic plants confirmed the presence of the introduced genes. In conclusion, T. latifolia could be genetically transformed by Agrobacterium tumefaciens.