In many plant beneficial rhizobacteria, QS mechanisms induce the synthesis of antimicrobial secondary metabolites and extracellular lytic enzymes with inhibitory effects towards other bacteria, fungi, protozoa, and nematodes [12]. The quorum quenching strategy using the lactonase AiiA was exploited to simultaneously quench the two AHL systems discovered in the endophytic strain G3 of S. plymuthica and

Torin 2 price investigate their role in controlling biocontrol-related phenotypes. The phenotypic analysis revealed that the strain G3/pME6863 expressing aiiA had https://www.selleckchem.com/products/isrib-trans-isomer.html reduced antifungal activity, chitinolytic and proteolytic activities, but increased of IAA biosynthesis, and had no impact on siderophore production compared with the strain carrying the vector TPX-0005 control G3/pME6000 and the wild type G3, indicating that QS control multiple biocontrol-related phenotypes in this strain. These results are in agreement with previous observations in the rhizospheric S. plymuthica HRO-C48 expressing AHL lactonases [14]. Depletion of AHLs with this lactonase resulted in altered adhesion and biofilm formation in vitro.

This was different from the closely related S. plymuthica strains HRO-C48 and RVH1, where biofilm formation for both strains is AHL-independent. In addition, in contrast to HRO-C48, swimming motility was not controlled by AHL-mediated QS [14, 33]. Attachment is required for biofilm formation and these are key processes in the interaction between bacteria and plant tissues which have been shown to rely on quorum sensing [44]. For example, in the biocontrol bacterium Pseudomonas chlororaphis strain 30-84, QS systems and their control over phenazine production play a role in the successful formation of surface-attached

populations required for biofilm formation. Transcriptome analysis revealed that phenazines as signals, up-regulated many of the genes related to cell adhesion and biofilm development, such old as fimbrial and lipopolysaccharides (LPS) genes [45]. The SwrIR quorum sensing system in S. marcescens MG1 plays a key role in biofilm development, from attachment to swarming motility, biofilm maturation and detachment, although QS regulation of adhesion in MG1 is surface dependent [37]. In S. marcescens strain 12, biofilm formation seems to rely on smaI, although this was measured using an attachment assay to a plastic microtitre plate [38], where SmaI is mainly responsible for C4-HSL synthesis. Pantoea stewartii causing Stewart’s vascular wilt and leaf blight in sweet corn and maize utilizes the EsaI/EsaR QS system to control virulence and effective colonization. EsaI shares 80% similarity to SplI of G3 and is a typical AHL synthase that also catalyzes preferentially the synthesis of 3-oxo-C6-HSL.