Characterization of the effector-triggered immune (ETI) response in plant roots

Effector-triggered immunity is a robust immune response that normally occurs following the recognition of proteins from pathogenic origins by host intracellular receptors. By taking advantage of knowledge from the root developmental field and plant immunology, we are activating ETI across a developmental gradient in 12 different cell types and characterizing how each cell type responds to ETI activation.

Revealing  the differential contribution of individual cell types in preventing pathogen spread

Soil-borne pathogens, such as Ralstonia solanacearum, actively kill root cells to get access to the vasculature and spread throughout their host plant. This poses an interesting conundrum. Indeed, the RRS1-R receptor has been found to recognize the avirulence protein PopP2 from R. solanacearum and activate ETI to limit disease progression. While an RRS1-R-PopP2 interaction leads to cell death in leaves, it remains unknown if a similar outcome arises in roots, where cell death would be beneficial for pathogen spreading.  By expressing RRS1-R in a cell-type-specific manner, we hope to resolve if any single cell type has an outsized role in preventing disease propagation. 

Investigation of the impact of plant development and immunity on spatial bacterial colonization at the root interface

Plant roots are constantly colonized by surrounding microbes in the environment. By mapping the spatial colonization of plant growth-promoting rhizobacteria (PGPR), we discovered that certain PGPRs become pathogenic on roots with mutations for genes involved in immune responses and developmental programmes. This observation is surprisingly independent of bacterial colonization and depends on proper expression of two independent genes in two different root cell types.

Revealing bacterial behavioral changes in response to plant developmental and immunity programs

In relation to the first section, we are investigating how plant immune and developmental programmes influence bacterial behavior. As we  observe dramatic shift from beneficial to pathogenic behavior in some of the most studied PGPRs in the scientific literature, we aim to understand how plants control bacterial programs to render them non-pathogenic.