Crosstalk between Plants and Bacteria - Elucidating the Role of Smoke Derived Karrikins

Aviad Mandabi, Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Michael Meijler, Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel

The term "quorum sensing" (QS) describes the ability of a population of bacteria to act as a single multicellular organism in a cell-density dependent manner. Bacteria achieve this by using small diffusible molecules to communicate with each other. Recently, naturally occurring molecules from forest fires were discovered to stimulate germination and seed dormancy breaking. It is known that bacteria and plants coexist in complex relationships that can be pathogenic, commensal or beneficial to the plant. These naturally occurring molecules, called karrikins, have structural similarity to known QS molecules, thus we hypothesize that these compounds can serve as signaling molecules for bacteria to induce or inhibit QS gene expression. These molecules might reveal a new communication pathway between bacteria and plants. We examined the response of different bacteria to these compounds. We synthesized two karrikins, KAR1 and KAR2, out of six and evaluated their effects on several bacteria. We discovered that KAR1/2 affects certain bacterial QS systems of P. aeruginosa, A. tumefaciens and V. cholerae in different manner.

We are currently exploring the mechanism through which these molecules interact with the bacteria. To do so we aim to identify and characterize the protein or proteins that interacting with these molecules.

We have synthesized azido-KAR1 analogs and we have started activity based protein profiling experiments in two bacteria species.