CSB Special Seminar: Professor Jeff Chang, Department of Botany and Plant Pathology, Oregon State University

We sequenced and analyzed genome sequences from over 175 Agrobacterium strains isolated from diseased plants and their environments. Based on chromosome sequences, the strains can be circumscribed within eight different clades, with some representing new taxa of Agrobacterium. Comparisons between the eight clades and sister clades yielded results that further exacerbate the fuzziness in taxonomical and biological distinction from mutualistic rhizobia. We also operationally categorized Ti/Ri plasmids into groups and revealed preferences between plasmids, bacterial host, and plant host. The generalizations that were drawn additionally help provide valuable insights into the dynamic evolutionary processes that shaped Ti/Ri plasmids and Agrobacterium virulence.