Study Reveals How Bacteria Bypass Plant Defenses

A study published in Science reports how bacteria can disable a plant's strong defenses.

Plants detect bacterial attack using specialized receptors that trigger defensive responses upon detection of a special part of the bacterial flagellin. The University of Oxford researchers found that pathogenic bacteria like Pseudomonas syringae produce glycosyrin, a unique molecule that blocks the plant's sugar-removing enzymes. Since the bacterial flagellin is covered with sugar, the glycosyrin prevents exposure of the bacteria's flagellin fragments. This makes the bacteria undetected by the plant's immune surveillance.

According to Frank Schroeder, a professor at the Boyce Thompson Institute who wrote a review about the study, the bacterial strategy is remarkably effective. “Not only does it prevent plants from recognizing bacterial invaders, but it also disrupts other aspects of plant defense. It changes the sugar patterns on plant proteins and causes sugar-containing compounds to accumulate in plant tissues, creating conditions that favor bacterial growth while suppressing plant defenses,” Schroeder adds.

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