Impact of three selected biotechnological strategies for potato pathogen control on the indigenous soil microbiot

In this project, we investigate possibilities to control plant diseases caused by bacteria according to three different approaches, i.e. genetic modification of plants (two approaches) and application of avirulent competitive bacterial strains. For that purpose we selected Ralstonia solanacearum and Erwinia carotovora as model organisms for controlling diseases, caused by both agents, in genetically modified potato lines and constructed avirulent mutants of R. solanacearum for suppression of brownrot in unmodified potato lines. Genetically modified potato lines are obtained from MPB Cologne (Germany) and from the Austrian Research Centre , Seibersdorf and these lines possesses insertions of genes encoding for bacterial lytic proteins. The lines obtained from MPB Cologne, denoted DL11, DL 12 and DL13 containT4 Lysozym gene from bacterial fage T4, whereas lines mas2C4-mas1 C4 and mas2C4-mas1 Att posses genes cecropin and both cecropin and attacin, respectively, from the giant silk moth Hyalophora cecropia. Further, mutants of R. solanacearum corrupted in expression of virulence genes via transposon insertion into the hrpB gene are used to control brownrot disease in potato. Using transgenic potato lines and non-pathogenic R. solanacearum strains, greenhouse and field studies are performed to investigate the efficacy of both approaches. Next to efficacy screening, the impact of heterologous gene expression and the presence of non-pathogenic R. solanacearum mutants on the microbial phytosphere community of potato will be investigated.