Premature Assault?

Plants may trick bacteria into attacking before the microbial population reaches a critical size, allowing the plants to successfully defend the weak invasion.

Feb 9, 2016
Jef Akst

DON MAYNARDUnable to move, plants must defend themselves against pathogens while staying in place. While they have a couple of strategies to kill off invaders, large numbers of pathogens can overwhelm the plant immune system. But if plants can trick bacteria into attacking too soon, before their population is big enough, plants may have a better chance of fighting back, according to a study published last month (January 5) in Science Signaling.

Tino Krell and colleagues from the Spanish National Research Council in Granada found that plants produce rosmarinic acid, which mimics a bacterial molecule that indicates the population density. The researchers hypothesize that the plants’ rosmarinic acid tricks bacteria into thinking their population is bigger than it actually is, prompting the microbes to invade too early, when the plant will be better able to fend them off.

“In vitro analysis showed that rosmarinic acid bound to RhlR, a transcriptional regulator in the quorum-sensing pathway of the plant and human pathogen Pseudomonas aeruginosa,” the researchers wrote in a summary of the paper. “Both reporter gene analysis and in vivo analysis of quorum-sensing responses showed that rosmarinic acid stimulated RhlR activity, thereby functioning as a mimic of the bacterial ligands. Identification of this molecular mimic has both agricultural and biomedical implications by enabling strategic disruption of bacterial communication.”

Hat tip: Science News