Engineered Auxotrophic Agrobacterium Strains Improve Plant Transformation
Bacterial overgrowth controlled without antibiotics
Auxotrophic strains of Agrobacterium tumefaciens can contribute to the development of more efficient plant transformation systems, especially for crops historically considered recalcitrant. A. tumefaciens has revolutionized plant science over the past decades due to its ability to transfer DNA into the cells of a wide range of plant species.
Successful transformation depends on the ability to control A. tumefaciens strains using antibiotics to prevent the bacteria from overgrowing explants in tissue culture. However, some antibiotics can affect tissue growth.
To develop more effective ways to control bacterial growth during plant transformation, researchers with the Center for Bioenergy Innovation engineered two A. tumefaciens strains auxotrophic for methionine (EHA105met and LBA4404met) as a counterselective agent alternative to antibiotics to cure plants of the bacterium.
Engineered auxotrophic A. tumefaciens strains prevented bacterial overgrowth on plants without the need for antibiotics. Furthermore, the engineered strains enabled biological containment of bacteria carrying transgenes.
Switchgrass and rice transformation were chosen to assess the performance of the auxotrophic A. tumefaciens strains, engineered via homologous recombination. Use of the strains minimized the need for antibiotics during transformation. Auxotrophy had no effect on the number of transfer DNA copies delivered by any of the strains evaluated, suggesting that the engineered strains exhibited the same transformation frequency as the parental strains.
University of Georgia, Athens
BER Program ManagerShing Kwok
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
Funding was provided by The Center for Bioenergy Innovation, a U.S. Department of Energy Research Center supported by the Biological and Environmental Research program in the DOE Office of Science.
Prías-Blanco, M., et al. 2022. “An Agrobacterium Strain Auxotrophic for Methionine is Useful for Switchgrass Transformation.” Transgenic Research. 31, 661-676. DOI:10.1007/s11248-022-00328-4.