Arachis hypogaea L. produces mimic and inhibitory quorum sensing like molecules

Abstract

A wide variety of plant-associated soil bacteria (rhizobacteria) communicate with each other by quorum sensing (QS). Plants are able to detect and produce mimics and inhibitor molecules of the QS bacterial communicative process. Arachis hypogaea L. (peanut) establishes a nitrogen-fixing symbiosis with rhizobia belonging to the genus Bradyrhizobium. These bacteria use a QS mechanism dependent on the synthesis of N-acyl homoserine lactones (AHLs). Given the relevance that plant-rhizobacteria interactions have at the ecological level, this work addresses the involvement of peanut in taking part in the QS mechanism. By using biosensor bacterial strains capable of detecting AHLs, a series of standard and original bioassays were performed in order to determine both (i) the production of QS-like molecules in vegetal materials and (ii) the expression of the QS mechanism throughout plant-bacteria interaction. Mimic QS-like molecules (mQS) linked to AHLs with long acyl chains (lac-AHL), and inhibitor QS-like molecules (iQS) linked to AHLs with short acyl chains (sac-AHL) were detected in seed and root exudates. The results revealed that synthesis of specific signaling molecules by the plant (such as mQS and iQS) probably modulates the function and composition of the bacterial community established in its rhizosphere. Novel bioassays of QS detection during peanut-Bradyrhizobium interaction showed an intense production of QS signals in the contact zone between root and bacteria. It is demonstrated that root exudates stimulate the root colonization and synthesis of lac-AHL by Bradyrhizobium strains in the plant rhizosphere, which leads to the early stages of the development of beneficial plant-bacteria interactions.

Water-Soluble Humic Materials Regulate Quorum Sensing in Sinorhizobium meliloti Through a Novel Repressor of expR

“…Moreover, our results suggest that WSHM function in a manner comparable to alfalfa seed exudates and may act as plant signal to repress expR gene expression in S. meliloti (Figure 4). Previous reports have demonstrated that plants are able to produce compounds that mimic or inhibit bacterial QS processes to promote their development of beneficial traits (Gao et al, 2003; Schikora et al, 2016; Nievas et al, 2017). WSHM might help plants to regulate bacterial QS and improve the symbiotic relationship between the host plant and bacteria.…”

“…Previous reports have evidenced that the eukaryotic hosts are capable of interfering with bacterial QS by producing molecular signals, like flavonoid (Kalia, 2013; Nievas et al, 2017), and flavonoid homologs have been detected in WSHM (Gao T.G. et al, 2015).…”

The plant compound rosmarinic acid induces a broad quorum sensing response in Pseudomonas aeruginosa PAO1

“…On the other hand, plants were found to synthesize compounds that interfere with bacterial QS (Venturi and Fuqua, 2013). It has been shown that mixtures of plant-derived compounds, including extracts (Biancalani et al, 2016;Tiwary et al, 2017), macerates (Ferluga et al, 2007;Subramoni et al, 2011;Rekha et al, 2017) and exudates (Teplitski et al, 2000;Gao et al, 2003;Nievas et al, 2017) interfere with bacterial QS mechanisms. Insight is now being gained into the nature of plant-derived QS modulating compounds that include flavonoids, phenolic acids and terpenoids (Silva et al, 2016).…”

Regulation Mediated by N-Acyl Homoserine Lactone Quorum Sensing Signals in the Rhizobium-Legume Symbiosis

“…Recently, the production of QS-like molecules by peanut plants ( Arachis hypogaea ) has been examined [ 121 ]. Peanut is a legume crop nodulated by Bradyrhizobium spp.…”