Analyzing the effect of strigolactones on the motility behavior of Rhizobia

Edited by Prandi, C., Cardinale, F.In the Rhizobium–legume symbiosis, strigolactones (SLs) promote root nodule formation; however, the exact mechanism underlying this positive effect remains unknown. The recent finding that an SL receptor legume mutant shows a wild-type nodulation phenotype suggests that SLs influence the symbiosis by acting on the bacterial partner. In agreement with this, the application of the synthetic SL analog GR24 on the alfalfa symbiont Sinorhizobium (Ensifer) meliloti has been shown to stimulate swarming, a specialized bacterial surface motility, which could influence infection of legumes by Rhizobia. Surface motility assays for many bacteria, and particularly for Rhizobia, are challenging. The establishment of protocols to study bacterial surface motility is key to decipher the role of SLs as rhizosphere cues for rhizobacteria. In this chapter, we describe a set of protocols implemented to study the different types of motility exhibited by S. meliloti.This work was supported by grants PGC2018-096477-B-I00, RTI2018-094350-B-C31 and AGL2017-88-083-R from the Spanish National R&D Plan of the Ministry of Science, Innovation and Universities Economy and Competitiveness, and European Regional Development Funds (MCIU/AEI/FEDER, EU)