This is a study of the mechanism of bacterial infection of susceptible plants. Integration of the Agrobacterium tumefaciens T-DNA into the plant genome results in characteristic pathology. Bacterial infection involves transfer of T-DNA and some proteins from the bacterium to the plant. T-DNA and virE2 protein transfer is mediated by proteins which are products of the bacterium virB operon. Studies planned are aimed at: (1) characterizing the behavior of the virB proteins, particularly the possible formation of membrane-associated aggregates. Cross-linking approaches will be employed. The expression stoichiometries of the virB proteins will be examined. The roles of individual virB proteins in the transport process will be evaluated via mutations of individual virB genes. (2) The transport mechanism itself will be examined through use of chemically modified or mutagenically modified virE2 protein, which may interfere with the transport mechanism. %%% Plant pathogens play an important role in the dynamics of the planetary biomass. More specifically, these pathogens affect ornamental as well as agriculturally important species. Therefore, beyond the intrinsic interest in the assembly of a complex system to transfer genetic information from the bacterium to the plant, the characterization of the infection process may lead to development of selective intervention strategies with economic and environmentally positive consequences. The studies planned utilize biochemical and genetic approaches to characterize the mechanisms by which bacteria infect susceptible plants.
