Plants trick bacteria into attacking too soon

Compound makes pathogens vulnerable to botanical defenses

raspberry leaf and microbes

This raspberry leaf (in a closeup, colorized electron micrograph) is covered in a biofilm of bacteria and fungi. Rosmarinic acid may keep bacterial visitors from overtaking a plant.

Stefan Diller/Science Source

Plants protect themselves from bacterial assault with mystery compounds that interrupt the bacteria’s best laid plans. Now, researchers have finally identified one of those protective compounds.

Rosmarinic acid is a plant’s secret weapon for disarming bacteria, researchers report in the Jan. 5 Science Signaling. Tino Krell and colleagues from the Spanish National Research Council in Granada found that rosmarinic acid mimics a molecule that bacteria use to signal each other in response to changes in population density. The compound fools bacteria into sending signals to their peers to invade a plant before the microbes have enough troops, so the plant can fight them off, the scientists speculate.

This defensive chemical might be useful for limiting bacterial crop damage and minimizing hospital infections caused by bacteria, the researchers say.

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