Plant genome complexity may be a factor limiting in situ the transfer of transgenic plant genes to the phytopathogen Ralstonia solanacearum

The development of natural competence by bacteria in situ is considered one of the main factors limiting transformation-mediated gene exchanges in the environment. Ralstonia solanacearum is a plant pathogen that is also a nat urally transformable bacterium that can develop the competence state during infection of its host. We have attempted to determine whether this bacteri um could become the recipient of plant genes. We initially demonstrated tha t plant DNA was released close to the infecting bacteria. We constructed an d tested various combinations of transgenic plants and recipient bacteria t o show that the effectiveness of such transfers was directly related to the ratio of the complexity of the plant genome to the number of copies of the transgene.