AgriLife Research leads collaboration to address zebra chip disease

Date:12-16-2024

Texas A&M AgriLife Research scientists are working on a new research project to fight plant diseases transmitted by psyllid insects — particularly the zebra chip disease, which has impacted potato production for decades.

Funded by a $682,500 grant from the U.S. Department of Agriculture National Institute of Food and Agriculture, this three-year project will investigate the mechanisms through which the bacterial pathogen Candidatus Liberibacter solanacearum affects plant and insect immune systems, leading to agricultural losses.

The findings by researchers in the Texas A&M College of Agriculture and Life Sciences could help significantly reduce pesticide dependency and enhance sustainable agricultural practices.

″The economic impact of diseases like zebra chip in potatoes has been enormous for Texas and other potato-producing states, especially in the Pacific Northwest,″ said principal investigator Julien Levy, Ph.D., AgriLife Research scientist in the Department of Horticultural Sciences. ″The only management system in place right now is applying pesticides to limit the spread of the disease by insects. Our research project aims to identify long-term solutions that help producers and the environment.″

The dark stripes on infected potatoes mark zebra chip disease. It has led to significant economic losses for producers due to reduced crop quality and marketability. (Fekede Workneh/Texas A&M AgriLife)

Tackling zebra chip

With zebra chip disease, bacteria establish an infection that disrupts plants’ nutrient transport systems — whether it be tomatoes or, most notably, potatoes. Frying infected potatoes to make chips produces dark stripes, which give the disease its name. In the past, if even a single potato in a batch was found to have zebra chip, the entire lot had to be thrown out.

″This disease has resulted in massive economic losses,″ said Cecilia Tamborindeguy, Ph.D., professor in the Department of Entomology. ″Although pesticide use has kept the disease somewhat under control, it’s not a sustainable solution, especially with rising production costs and other environmental concerns.″

In response, Levy and Tamborindeguy will be conducting a parallel study of plant and insect immune systems, as the bacteria must bypass both to spread infections. In particular, they’ll be investigating proteins the bacteria use to weaken the plant hosts’ defenses, as well as how those proteins could be blocked.

″The idea behind the project is to identify those proteins from the bacteria that are blocking the defense, and then we may be able to support the plant’s defense against the bacteria,″ Levy said.

While Levy leads investigations into the interactions between the bacteria and the plant, Tamborindeguy will be looking into the interactions between the bacteria and the psyllid responsible for spreading it.

″We have shown that the presence of the pathogen is also bad for the insect,″ she said. ″The bacteria are able to disrupt defenses at different stages in the life cycle and in different hosts. If we can improve both the insect and plant’s defense against the pathogen, it would provide an additional layer of protection.″

Broad applications in agriculture

The potato psyllid is a small, easy-to-miss insect vector that transmits zebra chip disease by feeding on plants. (Sam Craft/Texas A&M AgriLife)

The project builds on more than a decade of foundational research by Texas A&M AgriLife scientists. Both Tamborindeguy and Levy have studied psyllid-transmitted pathogens for years, contributing significant knowledge about the bacteria’s biology and their impact on agriculture.

The researchers hope their findings will pave the way for solutions to control the bacteria and protect their hosts, potentially breeding plants with enhanced resistance or developing biocontrol agents.

″This work not only benefits potato growers but also has implications for other crops facing similar threats,″ Levy said. ″By understanding the diversity of pathogens and their interactions, we’re creating tools that could protect future generations of crops.″

While the focus of this project is on solanaceous crops, like potatoes, tomatoes and peppers, the findings may extend to citrus greening, another bacterial disease spread by a psyllid insect that has caused significant agricultural damage.

″We’re building on years of work and continuously learning,″ Tamborindeguy said. ″This project is a step toward reducing our reliance on pesticides and improving the sustainability of agricultural systems.″