Research Project: A Multi-Scale Approach to Unearth the Root of Plant Disease Resistance

Plant root diseases cause up to 90 percent of disease loss. The best means of control is through breeding plant varieties that are resistant to potentially damaging diseases. Using tomato and a soilborne bacterial pathogen as a model, Dr. Iyer-Pascuzzi will focus on how roots mediate disease-resistance. Her research will explore which genes are associated with root-mediated resistance, how diseases changes root architecture, and whether roots and shoots signal each other to suppress disease symptoms.

iyer_photo_ffarAbout Dr. Iyer-Pascuzzi

Assistant Professor, Purdue University

As a child, my family and I would travel to India, my father’s native country. One of my earliest memories is driving through the streets of Mumbai, humbled by the children knocking on the car windows, begging for food. I believe my desire to alleviate global hunger was planted then. In a plant biology course at UC Berkeley, I realized I loved plant pathology, a subject with captivating biology that also addresses problems critical to global hunger. As a graduate student with Susan McCouch at Cornell, I focused on resistance in rice to Xanthomonas oryzae, and cloned the recessive resistance gene xa5. For my postdoc, I explored something different and studied roots in Philip Benfey’s lab at Duke. I was part of a team that developed a root architecture imaging system, and I examined Arabidopsis root cell-type specific responses to stress. My postdoc cemented a desire to continue in both root biology and plant pathology. My laboratory at Purdue combines these passions. Soilborne pathogens are responsible for severe crop loss each year. Roots are critical for resistance, but we understand very little of how roots defend themselves. The long-term goals of my laboratory are to identify the genes underlying root resistance to soilborne pathogens and to understand how they function, using the tomato – Ralstonia solanacearum pathosystem as a model. I love root biology and plant pathology because they combine fascinating biology with the ability to improve food security.



Q&A with Dr. Iyer-Pascuzzi

Take a peek inside the lab of plant pathologist Anjali Iyer-Pascuzzi, Ph.D., an assistant professor at Purdue University and 2016 FFAR New Innovator Award Winner. We set out to discover what inspired Dr. Iyer-Pascuzzi to begin her scientific career and how her work will impact agriculture.

When did you first know that you wanted to be a scientist?
I always wanted to have a career that made a difference in people's lives. When I was young, we used to visit India and I remember seeing children begging on the street for food. That image never left me and I wanted to find a way to improve the quality of life for others.

I used to think that meant being a doctor or being directly involved with people in need. When I was an undergraduate and exposed to plant science courses, I realized how science could change the world. I made the connection between how plant pathology could impact crops, which meant growing better food and reducing hunger across the globe.

Pathogens and disease can devastate crops, which can destroy a farmer's way of life or cause a country to experience food shortages. Research into plant disease resistance is vital for building a more secure food supply, which connects back to my childhood dreams of making a difference in the world.

Tell us about your research on root systems.
My lab works to understand root resistance to soil-borne pathogens. We focus on investigating Ralstonia solanacearum, which causes bacterial wilt. Most of the work combating this pathogen has focused above ground, but soil is the main route of infection in plants. Roots are most vulnerable to the disease, which prevents water from traveling properly from root to shoot.

The key to our work is understanding why some roots are resistant to pathogens. There are several ways to look at this and my lab is perusing multiple avenues for understanding root resistance. One project looked under the microscope to learn how the bacteria colonize a root system, which revealed that resistant roots delay colonization of the bacteria in comparison to non-resistant roots.

Now, we are looking at what genes expressed in the roots might cause this reaction. We also want to know what areas of the genome are important for resistance, which will ultimately help us create plants that express resistant characteristics.

How does your work impact farmers in the field?
Bacterial wilt is widespread issue in parts of the U.S., Europe, and Asia. It is classified as one of the most destructive plant pathogens in the world and attacks more than 200 plant species. Tomatoes are particularly susceptible to bacterial wilt - the disease can cause 90% disease loss in tomatoes worldwide.

If we found resistance genes, farmers would eventually be able to grow tomato varieties with good fruits that are also resistant to bacterial wilt. This would increase yields, decrease costs of treatment, and reduce the labor-intensive process of grafting. Ultimately, our research could be applied to many different crops that suffer from bacterial wilt and impact farmers in a significant way.