Presenter: Kyle Benzle
Advisor: Dr. John Finer, Department of Horticulture and Crop Science
Type: Master’s Degree
Title of Presentation: Evaluation of Different Agrobacterium Strains for Transformation of Soybean and Sunflower Tissues
Abstract: Greater than 90% of the soybean (Glycine max (L.) Merr) grown in the USA is transgenic with an estimated value of over $36 billion. The impact of soybean transgenics has been great, with recent emphasis on generation of a wide variety of transgenic traits. The transgenic soybean that is grown in the field today was primarily produced using Agrobacterium, a natural vector for gene introduction. Unfortunately, Agrobacterium-mediated transformation of soybean remains inefficient, and improvements in Agrobacterium transformation are still needed. In an attempt to recover strains that more efficiently transform plant tissues, different Agrobacterium strains were isolated from rhizospheric soil collected from soybean fields as well as from various plant galls. Nine new wild-type isolates, along with three previously identified laboratory strains, were selected and evaluated. Transformation efficiencies of these strains were evaluated in different tissues of soybean and sunflower seedlings, as well as in embryogenic suspension cultures of soybean. For sunflower transformation, a previously identified strain greatly outperformed all wild-type strains. This strain preferentially transformed vascular tissues compared to wild-type strains, which transformed all target tissues in the sunflower seedlings equally. In contrast, for soybean transformation, the novel wild-type strains gave the highest transformation rates in seedling tissues and embryogenic cultures, whereas the known lab strains were less efficient. This study shows that various tissues within different plants are differentially susceptible to Agrobacterium and that the potential exists for development of plant-specific Agrobacterium strains. Efforts continue to further characterize the novel Agrobacterium strains for improvements in soybean transformation.