Interaction of Pseudostellaria heterophylla with Quorum Sensing and Quorum Quenching Bacteria Mediated by Root Exudates in a Consecutive Monoculture System

Abstract

Many plant-pathogenic bacteria are dependent on quorum sensing (QS) to evoke disease. In this study, the population of QS and quorum quenching (QQ) bacteria was analyzed in a consecutive monoculture system of . The isolated QS strains were identified as with -type QS system and exhibited a significant increase over the years of monoculture. Only one QQ strain was isolated from newly planted soil sample and was identified as, which secreted lactonase to degrade QS signal molecules. Inoculation of to root could rapidly cause wilt disease, which was alleviated by . Furthermore, the expression of lactonase encoded by the gene in resulted in reduction of its pathogenicity, implying that the toxic effect of on the seedlings was QS-regulated. Meanwhile, excess lactonase in led to reduction in antibacterial substances, exoenzymes, and swarming motility, which might contribute to pathogensis on the seedlings. Root exudates and root tuber extracts of significantly promoted the growth of , whereas a slight increase of was observed in both samples. These results demonstrated that QS-regulated behaviors in mediated by root exudates played an important role in replanting diseases of.

Linking Short-Chain N-Acyl Homoserine Lactone-Mediated Quorum Sensing and Replant Disease: A Case Study of Rehmannia glutinosa

“…The results showed that numerous bacteria in soil were detected as QS bacteria, accounting for 32.5% of all randomly selected strains in the NP soil and 17% in the diseased soil. This observation is consistent with the findings in previous studies that QS systems are widespread among the bacterial populations in the phytosphere (Veselova et al, 2003;Zhang et al, 2016). Molecular identification found that the QS bacteria isolated from the healthy NP soil mainly consisted of Pseudomonas spp.…”

“…and stimulate certain pathogenic bacteria and fungi (Wu et al, 2016c;Chen et al, 2017). Zhang et al (2016) also demonstrated that both root exudates and tuberous root extracts of P. heterophylla could significantly promote the growth of S. marcescens, a QS bacterium that rapidly causes wilt disease of P. heterophylla. Numerous studies indicated that indirect allelopathy through modifications in soil microbiome induced by root exudates contributes to replant disease in agriculture and horticulture (Li et al, 2014;Chen et al, 2018).…”

“…A previous study on P. heterophylla replant disease indicated that the number of QS bacteria, all identified as Serratia marcescens that can rapidly cause wilt disease, significantly increased with the increasing years of monoculture. Moreover, it was found that P. heterophylla root exudates and root tuber extracts could significantly promote the growth of S. marcescens (Zhang et al, 2016). Our previous studies have demonstrated that consecutive R. glutinous monoculture led to soil microbiome dysbiosis, and phenolic acids in root exudates could significantly promote the mycelial growth and toxin production of pathogenic F. oxysporum (Wu et al, 2015(Wu et al, , 2018a.…”

Pathogen-Mediated Assembly of Plant-Beneficial Bacteria to Alleviate Fusarium Wilt in Pseudostellaria heterophylla

“…In turn, plants regulate their growth and motility under biotic stress or abiotic stress ( Chakraborty and Newton, 2011 ; Liu et al, 2019b , 2020 ). Continuous monoculture leads to many soil-borne pathogens in the soil and a high biotic stress environment for plants, which leads to an increased incidence of disease ( Lapsansky et al, 2016 ; Zhang et al, 2016 ; Kong et al, 2019 ; Liu et al, 2019a ). In recent years, many researchers have found that the enrichment of beneficial microbes in the soil mediated by pathogen infection can alleviate soil-borne disease and expand plant defensive capabilities ( Elad et al, 2010 ).…”

Phomopsis tersa as Inhibitor of Quorum Sensing System and Biofilm Forming Ability of Pseudomonas aeruginosa

“…QS inhibition (QSI) can be achieved via different mechanisms such as inhibition of signaling molecule production, blocking the binding of AHL molecule to the receptors, alteration in the structure of target molecule by enzymes and interrupting the transport facility of the signaling molecule through the membrane channel. Molecules interfering with the QSS have gained importance to develop anti-infective drugs [7][8][9]. Natural compounds from plants as well as microbial sources are highly important to combat microbial pathogenicity especially drug resistant bacteria [10][11][12].…”