Researchers studied how Arabidopsis plants respond to infection by the fungus Fusarium graminearum by examining changes in small RNA molecules called microRNAs. They found that the plant activates specific microRNAs early in infection, even before visible disease symptoms appear. Two particularly important microRNAs, miR855 and miR826a, were identified as potential key regulators of the plant’s defense response. These findings could help scientists develop crop varieties with improved resistance to fungal diseases that cause significant agricultural losses worldwide.