Regulation of phenotypic switching and heterogeneity in Photorhabdus luminescens cell populations

The insect pathogen and nematode symbiont Photorhabdus luminescens exists in two phenotypically different forms designated as primary and secondary variants. These variants are genetically homogeneous but differ in various morphological and physiological traits. One of the most dominating differences between both variants is that secondary cells are deficient in nematode symbiosis. During growth within the insect, single cells undergo phenotypic switching and are then disabled in re-association with the nematodes. The social aspect of this phenomenon is not understood yet and will be investigated in the current project. Moreover, the regulator HexA is known to control the switching process. How HexA controls bistable gene expression and which signals are involved to induce phenotypic switching are central questions that we attempt to address in the current project.