A sweet revenge for fungal disease

Sweet potato black rot is a devastating disease caused by the fungus Ceratocystis fimbriata. Since the late 1800s, sweet potato black rot has threatened to destroy 30% of the sweet potato crop in the United States. In 2015, all sweet potato-producing states in the United States experienced one of the worst outbreaks on record, with losses of up to 60% reported.

Although fungicides can help control the disease, they are not a permanent solution, especially in key export markets where restrictions on fungicide residues are volatile. An additional management strategy is performance-assisted breeding—a novel approach to breeding disease-resistant crops.

Effectors are proteins secreted from pathogens that modify their plant hosts at the molecular and cellular levels. Instead of traditional breeding methods, which can take years and involve extensive trial and error, efficiency-assisted breeding uses a specific effect from the pathogen to quickly identify and select resistant plants. This accelerates breeding programs, leading to the development of black rot-resistant sweet potato varieties and reducing crop losses.

Until now, researchers had limited knowledge of C. fimbriata biology, thus posing a hurdle in managing this disease. To address this, researcher Camilo Parada-Rojas and colleagues from Lina Quezada-Ocampo’s lab at North Carolina State University focused on identifying effector proteins produced by C. fimbriata during infection.

study, Published Inside Molecular Plant-Microbe Interactions (MPMI), 31 C. fimbriata effector genes were identified. By charting these effects, researchers can better understand how the fungus affects sweet potato and identify potential host targets for breeding resistant varieties. In addition, the study suggests a biotrophic phase in which the fungus can survive in sweet potato storage roots before killing it, providing a new perspective on how the disease progresses.

This research provides pioneering knowledge on the biology of C. fimbriata and highlights potential targets for efficiency-assisted breeding. Although the findings are promising, practical applications in disease control and plant breeding will require more time and research.

Barada-Rojas says, „It’s been a long journey from basic research to real-world application, but the potential to have a significant impact on crop resilience and food security is incredibly rewarding.”

Meanwhile, insights from the study of pathogen evolution and persistence can inform disease surveillance, helping to more effectively monitor and manage the spread of C. fimbriata—taking the science one step closer to future-proofing sweet potatoes.