Homoserine lactones: Do plants really listen to bacterial talk?

The bacterial quorum sensing signals N-acyl-L-homoserine lactones (AHL) enable bacterial cells to regulate gene expression depending on population density, which eventually leads to invasion of hosts. Only little is known about the molecular ways of plants reacting to these bacterial signals. Recently, we showed that the contact of Arabidopsis thaliana roots with N-hexanoyl-DL- homoserine-lactone (HHL) resulted in distinct transcriptional changes in roots and shoots, respectively. In addition, we provided evidence that Arabidopsis takes up bacterial AHLs, which are obviously transported throughout the plant. In sum, the bacterial quorum sensing signal AHL seems to influence plant growth, and may contribute to reprogram plants encountering bacterial pathogens or rhizosphere bacteria. However, as pointed out here, the response of plants to bacterial AHLs may depend on plant species and chemical structure of AHLs.