PubMed · 2026-05-28
Not all microbes in a plant's leaf community are equally helpful against disease — it depends on which specific microbes are present and how they interact with each other, not just how many there are.
Individual yeasts fell into three categories: antagonists that reduced rust severity, facilitators that worsened it, and neutrals — with most falling into the neutral category.
Yeast community composition matters more than diversity: a rust-promoting yeast was neutralized when other yeasts were added, but adding yeasts to a rust-fighting community paradoxically increased disease severity.
Strong competition between yeast species was confirmed in lab tests, suggesting that competitive dynamics — not just each microbe's individual effect — drive the disease outcomes seen in mixed communities.
