About 7% of powdery mildew samples collected across 28 countries over a 150-year span are infected by Ampelomyces, an intracellular fungus that targets plant diseases.
That figure emerges from a North Carolina State University study published in Proceedings B and reported by Mirage News.
Because powdery mildews cannot be cultured in a lab, researchers screened over 600 dried samples from the NC State herbarium alongside data from GenBank. This approach revealed a much higher prevalence of the hyperparasite than previously documented.
Among the GenBank specimens screened in the study, around 15% of those labeled as Ampelomyces were misidentified. Michael Bradshaw said that this inaccuracy stems from relying on large datasets where anyone can input information.
“These parasites are hard to identify, so what happens is someone misidentifies them and enters incorrect data,” said Michael Bradshaw, corresponding author of the study and an assistant professor of entomology and plant pathology at NC State. “Then someone else sees that wrong data and uses it to classify their own samples, which leads to more wrong data, and it amplifies that way.”
The research demonstrates how herbaria can serve as archives to observe biological interactions like hyperparasites. Bradshaw explained that understanding these strains could lead to better methods for containing powdery mildew.
“By understanding hyperparasite diversity and how many different strains are out there, it might give us insights on if some are better at controlling the fungus than others,” Bradshaw told Mirage News. “There is a degree of host specificity to these hyperparasites, and if we are able to delve deeper they may be very useful in containing this plant disease.”
