How do root systems defend themselves against soil-borne pathogens?

Plant root systems are vital to plant health and fitness, as they uptake water, nutrients, and provide anchorage in soil. They are also continually confronted by different soil-borne plant pathogens that can severely harm susceptible plants, decreasing yield and plant fitness.

Vascular wilt root diseases are caused by soil-borne bacteria and fungi that first infect root systems and colonize xylem, preventing water movement from the root to the shoot. The aboveground region of the plant begins to wilt, ultimately leading to plant death. These are among the most challenging plant diseases to control and are found throughout the world. They are best controlled by resistant varieties, but the mechanisms underlying resistance are poorly understood. Since root infection is the first step in the disease process, we hypothesize that focusing on root systems will enable us to identify resistance mechanisms occurring early in the disease process, prior to plant wilting.  Understanding the mechanisms of root – mediated resistance is a key part of controlling these diseases.

Our specific questions include:

What is the role of root anatomy and root architecture in disease resistance? 

Do plant pathogens actively target proteins with roles in root architecture?

How do root cell-type specific transcriptional programs differ between resistant and susceptible plants?

What genes are necessary for resistance mediated by roots? How do they function? 

How do different soil amendments alter pathogen infection?

How does root cap cell release alter resistance or susceptibility to soil-borne pathogens?

To address these questions we focus primarily on the interaction between tomato and the soil-borne bacterium Ralstonia solanacearum.  R. solanacearum is a globally devastating pathogen and the causal agent of bacterial wilt. The bacterium infects over 200 plant species in 50 different plant families, and is particularly devastating in tomato. Tomato has excellent genetic resources, and a root system typical of many dicots. The tomato – R. solanacearum pathosystem is an excellent model for studies of root diseases.

We work at multiple scales – from the cell-type to whole organism, and incorporate molecular biology, genetics, genomics, plant pathology and phenotyping tools to address our questions. Our long-term goal is to discover the genes and underlying mechanisms that lead to improved crop production by improving a plant’s ability to withstand soil-borne pathogens.

We are always looking for talented, excited graduate students or post-docs interested in roots and plant diseases!