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N-acyl homoserine lactones in diverse Pectobacterium and Dickeya plant pathogens: diversity, abundance, and involvement in virulence.

Crépin A, Beury-Cirou A, Barbey C, Farmer C, Hélias V, Burini JF, Faure D, Latour X - Sensors (Basel) (2012)

Bottom Line: All the NAHSL-lactonase expressing strains produced a lower amount of NAHSLs as compared to those harboring the empty vector.This work highlights that quorum sensing similarly contributed to virulence in most of the tested Pectobacterium and Dickeya, even the strains had been isolated recently or during the past decades.Thus, these key regulatory-molecules appear as credible targets for developing anti-virulence strategies against these plant pathogens.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Microbiologie Signaux et Microenvironnement, Normandie Université, Université de Rouen EA 4312, IUT Evreux, Evreux, France. alexandre.crepin@etu.univ-rouen.fr

ABSTRACT
Soft-rot bacteria Pectobacterium and Dickeya use N-acyl homoserine lactones (NAHSLs) as diffusible signals for coordinating quorum sensing communication. The production of NAHSLs was investigated in a set of reference strains and recently-collected isolates, which belong to six species and share the ability to infect the potato host plant. All the pathogens produced different NAHSLs, among which the 3-oxo-hexanoyl- and the 3-oxo-octanoyl-L-homoserine lactones represent at least 90% of total produced NAHSL-amounts. The level of NAHSLs varied from 0.6 to 2 pg/cfu. The involvement of NAHSLs in tuber maceration was investigated by electroporating a quorum quenching vector in each of the bacterial pathogen strains. All the NAHSL-lactonase expressing strains produced a lower amount of NAHSLs as compared to those harboring the empty vector. Moreover, all except Dickeya dadantii 3937 induced a lower level of symptoms in potato tuber assay. Noticeably, aggressiveness appeared to be independent of both nature and amount of produced signals. This work highlights that quorum sensing similarly contributed to virulence in most of the tested Pectobacterium and Dickeya, even the strains had been isolated recently or during the past decades. Thus, these key regulatory-molecules appear as credible targets for developing anti-virulence strategies against these plant pathogens.

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Concentrations of the main N-acyl homoserine lactones produced by Pectobacterium and Dickeya strains.NAHSLs were extracted from PGA medium culture supernatants of reference strains (a) and recent strains isolated from fields (b) during the transition from exponential to stationary phases and quantified by HPLC coupled to mass spectrometry. For each point, at least 3 independent cultures were analyzed, with standard deviation shown. Legend: white bars, N-3-oxo-hexanoyl-l-homoserine lactone; gray bars, N-3-oxo-octanoyl-l-homoserine lactone.
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f2-sensors-12-03484: Concentrations of the main N-acyl homoserine lactones produced by Pectobacterium and Dickeya strains.NAHSLs were extracted from PGA medium culture supernatants of reference strains (a) and recent strains isolated from fields (b) during the transition from exponential to stationary phases and quantified by HPLC coupled to mass spectrometry. For each point, at least 3 independent cultures were analyzed, with standard deviation shown. Legend: white bars, N-3-oxo-hexanoyl-l-homoserine lactone; gray bars, N-3-oxo-octanoyl-l-homoserine lactone.

Mentions: The characterization of NAHSL signal molecules was carried out on a mineral salt medium supplemented with PGA, a plant cell-wall compound which contributes to induce the synthesis of signaling molecules and virulence factors as in situ conditions [10]. Culture supernatants were recovered during the transition from exponential-phase to stationary-phase growth, when the cell density reached the quorum and the NAHSL concentration is the highest. Produced NAHSLs were identified and quantified using HPLC coupled with mass spectrometry. In these experimental conditions, all P. atrosepticum strains produced mainly (90%) N-3-oxo-octanoyl-l-HSL (3-oxo-C8-HSL) and a low percent of N-octanoyl-l-HSL (C8-HSL) and N-3-oxo-hexanoyl-l-HSL (3-oxo-C6-HSL). They also synthesized traces (<1%) of N-hexanoyl-l-HSL (C6-HSL) and N-3-oxo-decanoyl-l-HSL (3-oxo-C10-HSL) (Figure 1). Among these strains, P. atrosepticum CFBP 6276 and 1526T were the largest producers of 3-oxo-C8-HSL with amounts greater than 1 pg/cfu (Figure 2). The other P. atrosepticum strains displayed lower production of the major NAHSL with about 0.6 pg/cfu. All Dickeya spp. strains and three of the four studied P. carotovorum strains produced mainly 3-oxo-C6-HSL and minor percentages of 3-oxo-C8-HSL (Figure 1).


N-acyl homoserine lactones in diverse Pectobacterium and Dickeya plant pathogens: diversity, abundance, and involvement in virulence.

Crépin A, Beury-Cirou A, Barbey C, Farmer C, Hélias V, Burini JF, Faure D, Latour X - Sensors (Basel) (2012)

Concentrations of the main N-acyl homoserine lactones produced by Pectobacterium and Dickeya strains.NAHSLs were extracted from PGA medium culture supernatants of reference strains (a) and recent strains isolated from fields (b) during the transition from exponential to stationary phases and quantified by HPLC coupled to mass spectrometry. For each point, at least 3 independent cultures were analyzed, with standard deviation shown. Legend: white bars, N-3-oxo-hexanoyl-l-homoserine lactone; gray bars, N-3-oxo-octanoyl-l-homoserine lactone.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376598&req=5

f2-sensors-12-03484: Concentrations of the main N-acyl homoserine lactones produced by Pectobacterium and Dickeya strains.NAHSLs were extracted from PGA medium culture supernatants of reference strains (a) and recent strains isolated from fields (b) during the transition from exponential to stationary phases and quantified by HPLC coupled to mass spectrometry. For each point, at least 3 independent cultures were analyzed, with standard deviation shown. Legend: white bars, N-3-oxo-hexanoyl-l-homoserine lactone; gray bars, N-3-oxo-octanoyl-l-homoserine lactone.
Mentions: The characterization of NAHSL signal molecules was carried out on a mineral salt medium supplemented with PGA, a plant cell-wall compound which contributes to induce the synthesis of signaling molecules and virulence factors as in situ conditions [10]. Culture supernatants were recovered during the transition from exponential-phase to stationary-phase growth, when the cell density reached the quorum and the NAHSL concentration is the highest. Produced NAHSLs were identified and quantified using HPLC coupled with mass spectrometry. In these experimental conditions, all P. atrosepticum strains produced mainly (90%) N-3-oxo-octanoyl-l-HSL (3-oxo-C8-HSL) and a low percent of N-octanoyl-l-HSL (C8-HSL) and N-3-oxo-hexanoyl-l-HSL (3-oxo-C6-HSL). They also synthesized traces (<1%) of N-hexanoyl-l-HSL (C6-HSL) and N-3-oxo-decanoyl-l-HSL (3-oxo-C10-HSL) (Figure 1). Among these strains, P. atrosepticum CFBP 6276 and 1526T were the largest producers of 3-oxo-C8-HSL with amounts greater than 1 pg/cfu (Figure 2). The other P. atrosepticum strains displayed lower production of the major NAHSL with about 0.6 pg/cfu. All Dickeya spp. strains and three of the four studied P. carotovorum strains produced mainly 3-oxo-C6-HSL and minor percentages of 3-oxo-C8-HSL (Figure 1).

Bottom Line: All the NAHSL-lactonase expressing strains produced a lower amount of NAHSLs as compared to those harboring the empty vector.This work highlights that quorum sensing similarly contributed to virulence in most of the tested Pectobacterium and Dickeya, even the strains had been isolated recently or during the past decades.Thus, these key regulatory-molecules appear as credible targets for developing anti-virulence strategies against these plant pathogens.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Microbiologie Signaux et Microenvironnement, Normandie Université, Université de Rouen EA 4312, IUT Evreux, Evreux, France. alexandre.crepin@etu.univ-rouen.fr

ABSTRACT
Soft-rot bacteria Pectobacterium and Dickeya use N-acyl homoserine lactones (NAHSLs) as diffusible signals for coordinating quorum sensing communication. The production of NAHSLs was investigated in a set of reference strains and recently-collected isolates, which belong to six species and share the ability to infect the potato host plant. All the pathogens produced different NAHSLs, among which the 3-oxo-hexanoyl- and the 3-oxo-octanoyl-L-homoserine lactones represent at least 90% of total produced NAHSL-amounts. The level of NAHSLs varied from 0.6 to 2 pg/cfu. The involvement of NAHSLs in tuber maceration was investigated by electroporating a quorum quenching vector in each of the bacterial pathogen strains. All the NAHSL-lactonase expressing strains produced a lower amount of NAHSLs as compared to those harboring the empty vector. Moreover, all except Dickeya dadantii 3937 induced a lower level of symptoms in potato tuber assay. Noticeably, aggressiveness appeared to be independent of both nature and amount of produced signals. This work highlights that quorum sensing similarly contributed to virulence in most of the tested Pectobacterium and Dickeya, even the strains had been isolated recently or during the past decades. Thus, these key regulatory-molecules appear as credible targets for developing anti-virulence strategies against these plant pathogens.

Show MeSH
Related in: MedlinePlus