Texas A&M AgriLife Research scientists have developed a promising new approach to combat two major agricultural diseases in the U.S.: citrus greening and potato zebra chip. By using spinach-derived antimicrobial peptides, or defensins, the researchers have demonstrated significant improvements in crop yield and quality for affected plants.
The study, recently published in the Plant Biotechnology Journal, was led by Dr. Kranthi Mandadi, a plant molecular biologist and professor at the Texas A&M AgriLife Research and Extension Center in Weslaco. Mandadi and his team focused on spinach defensins because they are naturally occurring compounds known to defend plants against a wide range of pathogens, including fungi and bacteria. Since these peptides are already present in a common food crop, they are considered safe for human consumption. In 2021, the U.S. Environmental Protection Agency confirmed that dietary exposure to spinach defensins poses no health risk, including for infants and children.
The research team used a benign virus, developed by the University of Florida, to deliver the peptides to commercial citrus trees infected with Candidatus Liberibacter asiaticus, the bacterium responsible for citrus greening disease. The virus infects the trees in the same area where the bacteria reside. Through a simple grafting procedure, the virus was introduced to the trees, enabling it to deliver the peptides internally. Over several years, treated trees showed promising results, including up to a 50% increase in fruit yield after a single application, compared to untreated trees.
Citrus greening disease severely impacts fruit quality, causing misshapen, bitter fruit that drops prematurely. The disease weakens trees and leads to billions in agricultural losses annually. The success of this peptide-based treatment could offer citrus growers a much-needed solution.
The team also tested the spinach peptides on potatoes affected by Candidatus Liberibacter solanacearum, the pathogen responsible for zebra chip disease. When introduced into potatoes, the peptides significantly reduced disease symptoms, lowered bacterial presence, and improved tuber quantity and quality.
Encouraged by these results, Mandadi aims to expand the research further. He plans to explore combining different peptides and integrating them with existing pest management strategies, especially those targeting the insects that transmit these pathogens. "This is just the beginning," said Mandadi. "These antimicrobial peptides could become a broad-spectrum treatment tool for multiple crops alongside traditional practices."
Southern Gardens Citrus, a subsidiary of U.S. Sugar, has licensed the peptide technology from Texas A&M University System and the viral delivery method from the University of Florida. Together with Silvec Biologics, they are working to commercialize the innovation. Silvec filed an application with the EPA in January 2024 to approve commercial use, a key step in making the treatment available to growers.
For more information:
Laura Muntean
Texas A&M AgriLife
Tel: +1 601 248 1891
Email: [email protected]
www.agrilifetoday.tamu.edu