Location: Foreign Disease-Weed Science Research
Project Number: 8044-22000-051-047-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2026
End Date: Aug 31, 2027
Objective:
Peanut smut is a significant disease impacting peanut production in Argentina, capable of causing up to 30% yield loss. Although not yet present in the U.S., its potential establishment poses a critical concern for growers and stakeholders. While the genetic diversity of the peanut smut pathogen is well-characterized in Argentine production zones, uncharacterized pathogen reservoirs persist in wild peanut species across South America. As peanut production expands in the region, there's a risk that pathogen populations maintained on wild hosts could interbreed with the epidemic population. This interbreeding might lead to an explosion of novel genetic diversity, rapid evolutionary change, and the emergence of highly virulent individuals. Such developments could ultimately undermine the durability of newly identified host resistance, which represents a crucial tool for managing the disease if it were to reach the U.S.
Therefore, the objective of this agreement is for the Cooperator to organize and conduct three collecting trips to northern Argentina, Bolivia, and Paraguay. During these trips, the Cooperator will search for and collect isolates of the peanut smut pathogen from wild peanut hosts. These isolates will then be sent to ARS for genetic characterization. This characterization will inform risk assessments concerning the threat these wild pathogen reservoirs may pose to the durability of host resistance.
Approach:
The Cooperator will take three expeditions to search for and collect infected wild peanuts. Areas targeted will include: 1) the Gran Chaco region of northern Argentina (Salta and Jujuy Provinces), where large-scale peanut production is now present; 2) Filadelfia, Paraguay, where peanut cultivation is known to occur; and 3) Bolivia, where the Cooperator recently collected infected wild peanuts. Wild peanut populations will be scouted for based on distribution maps and environmental and spatiotemporal considerations. When located, pods will be collected, and hand shelling of several representative samples will occur in the field to see if there is evidence of smut. If initial evidence of smut is observed, further collecting at this location will occur. At the conclusion of each expedition, all collected peanuts will be shelled by hand. If the pathogen is found, spores from individual pods will be placed in a 1.5 ml tube, parafilmed and prepared for shipment to the USDA-ARS Foreign Disease-Weed Science Research Unit (FDWSRU) in Frederick, MD. The goal is to collect ~30 pathogen isolates from wild peanut hosts. The Cooperator is to obtain all necessary provincial and country permits for collecting and export. Once in the possession of ARS, the spores from individual peanuts will be subjected to high-throughput sequencing in order to characterize the genetic diversity of pathogen populations on wild host relatives and develop a risk assessment.