Research topics

 

1. Genetic determinants of Disease.

For this part of our research, we use the wide-host range pathogen Ralstonia solanacearum as a model. R solanacearum is a soil-borne pathogen whose major virulence determinant is the type III secretion system (T3SS). This secretion machinery delivers bacterial effector proteins into host cells, in an engaging example of information transfer between evolutionary distant organisms. In addition, the main regulatory cascades controlling expression of the T3SS and other virulence genes is well characterised. We are currently addressing the following questions:

 

2. Metacaspases as executioners of programmed cell death.

 

Programmed cell death (PCD) is an essential process for normal development and defense against pathogens in all multicellular organisms. Some of its key regulators evolved from primordial molecules likely serving homeostatic functions in a unicellular common ancestor. In animals and plants, millions of years of separate evolution have resulted in unique and exquisitely fine-tuned PCD systems which still serve the most important function: keeping the organism alive. In animals, the execution systems that control cell death involve a limited number of pathways that converge on the activation of the caspase family of proteases. In contrast, in plants very little is known about the mechanisms that commit a cell to die after perception of a cell death-trigger.
We have recently shown that metacaspases, distant relatives of caspases, are main regulators of PCD in plants: Type I metacaspases AtMC1 and AtMC2 antagonistically control pathogen-triggered cell death upon innate immune receptor activation (Coll et al. Science 2010), also known as the hypersensitive response (HR) cell death. Despite the fact that the metacaspases are divergent from animal caspases, they control similar processes, suggesting an ancient evolutionary link between cell death control and innate immune system, analogous in plants and animals. We are currently studying: