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See detailNew linear lipopeptides produced by pseudomonas cichorii SF1-54 are involved in virulence, swarming motility, and biofilm formation
Pauwelyn, E.; Huang, C. J.; Ongena, Marc ULg et al

in Molecular Plant-Microbe Interactions [=MPMI] (2013), 26(5), 585-598

Pseudomonas cichorii is the causal agent of lettuce midrib rot, characterized by a dark-brown to green-black discoloration of the midrib. Formation of necrotic lesions by several plant-pathogenic ... [more ▼]

Pseudomonas cichorii is the causal agent of lettuce midrib rot, characterized by a dark-brown to green-black discoloration of the midrib. Formation of necrotic lesions by several plant-pathogenic pseudomonads is associated with production of phytotoxic lipopeptides, which contribute to virulence. Therefore, the ability of P. cichorii SF1-54 to produce lipopeptides was investigated. A cell-free culture filtrate of SF1-54 showed surfactant, antimicrobial, and phytotoxic activities which are typical for lipopeptides. High-performance liquid chromatography analysis of P. cichorii SF1-54 culture filtrate revealed the presence of seven compounds with lipopeptide characteristics. Two related lipopeptides, named cichofactin A and B, were studied in more detail: they are linear lipopeptides with a decanoic and dodecanoic lipid chain, respectively, connected to the N-terminus of an eight-amino-acid peptide moiety. Both cichofactins are new members of the syringafactin lipopeptide family. Furthermore, two nonribosomal peptide synthethase-encoding genes, cifA and cifB, were identified as responsible for cichofactin biosynthesis. A cifAB deletion mutant no longer produced cichofactins and was impaired in swarming motility but showed enhanced biofilm formation. Upon spray inoculation on lettuce, the cichofactindeficient mutant caused significantly less rotten midribs than the wild type, indicating that cichofactins are involved in pathogenicity of P. cichorii SF1-54. Further analysis revealed that P. cichorii isolates vary greatly in swarming motility and cichofactin production. © 2013 The American Phytopathological Society. [less ▲]

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See detailAmino Acids, Iron, and Growth Rate as Key Factors Influencing Production of the Pseudomonas Putida Btp1 Benzylamine Derivative Involved in Systemic Resistance Induction in Different Plants
Ongena, MARC ULg; Jourdan, Emmanuel ULg; Adam, Akram et al

in Microbial Ecology (2008), 55(2), 280-92

The biological control bacterium Pseudomonas putida BTP1 exerts its protective effect mostly by inducing an enhanced state of resistance in the host plant against pathogen attack [induced systemic ... [more ▼]

The biological control bacterium Pseudomonas putida BTP1 exerts its protective effect mostly by inducing an enhanced state of resistance in the host plant against pathogen attack [induced systemic resistance (ISR)]. We previously reported that a specific compound derived from benzylamine may be involved in the elicitation of the ISR phenomenon by this Pseudomonas strain. In this article, we provide further information about the N,N-dimethyl-N-tetradecyl-N-benzylammonium structure of this determinant for ISR and show that the benzylamine moiety may be important for perception of the molecule by root cells of different plant species. We also investigated some regulatory aspects of elicitor production with the global aim to better understand how in situ expression of these ISR elicitors can be modulated by physiological and environmental factors. The biosynthesis is clearly related to secondary metabolism, and chemostat experiments showed that the molecule is more efficiently produced at low cell growth rate. Interestingly, the presence of free amino acids in the environment is necessary for optimal production, and a specific positive effect of phenylalanine was evidenced in pulsed continuous cultures. The influence of other abiotic factors, such as mineral content, oxygen concentration, or pH, on elicitor production is also reported and discussed with respect to the specific conditions that the producing strain undergoes in the rhizosphere environment. [less ▲]

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See detailOrnicorrugatin, A New Siderophore From Pseudomonas Fluorescens Af76
Matthijs, S.; Budzikiewicz, H.; Schafer, M. et al

in Zeitschrift für Naturforschung. C, Journal of Biosciences (2008), 63(1-2),

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See detailIsolation of an n-alkylated benzylamine derivative from Pseudomonas putida BTP1 as elicitor of induced systemic resistance in bean
Ongena, MARC ULg; Jourdan, Emmanuel ULg; Schafer, M. et al

in Molecular Plant-Microbe Interactions (2005), 18(6), 562-569

Root treatment of Phaseolus vulgaris with the nonpathogenic Pseudomonas putida BTP1 led to significant reduction of the disease caused by the pathogen Botrytis cinerea on leaves. The molecular determinant ... [more ▼]

Root treatment of Phaseolus vulgaris with the nonpathogenic Pseudomonas putida BTP1 led to significant reduction of the disease caused by the pathogen Botrytis cinerea on leaves. The molecular determinant of P putida BTP1 mainly responsible for the induced systemic resistance (ISR) was isolated from cell-free culture fluid after growth of the strain in the iron-poor casamino acid medium. Mass spectrometry analyses performed on both the bacterial product and synthetic analogues revealed a polyalkylated benzylamine structure, with the quaternary ammonium substituted by methyl, ethyl, and C-13 aliphatic groups responsible for the relative hydrophobicity of the molecule. The specific involvement of the N-alkylated benzylamine derivative (NABD) in ISR elicitation was first evidenced by testing the purified compound that mimicked the protective effect afforded by crude supernatant samples. The evidence was supported by the loss of elicitor activity of mutants impaired in NABD biosynthesis. Our experiments also showed that other iron-regulated metabolites secreted by the strain are not involved in ISR stimulation. Thus, these results indicate a wider variety of Pseudomonas determinants for ISR than reported to date. [less ▲]

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See detailThe Pyoverdins Of Pseudomonas Syringae And Pseudomonas Cichorii
Bultreys, A.; Gheysen, I.; Wathelet, Bernard ULg et al

in Zeitschrift Fur Naturforschung C-A Journal of Biosciences (2004), 59(9-10),

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See detailThe Pyoverdin Of Pseudomonas Fluorescens Btp2, A Novel Structural Type
Ongena, MARC ULg; Jacques, P.; Thonart, Philippe ULg et al

in Tetrahedron Letters (2001), 42(34),

Abstract—From Pseudomonas fluorescens BTP2 a pyoverdin was isolated which contained the so far not encountered Val in its peptide chain. Its structure could be elucidated by chemical degradation and ... [more ▼]

Abstract—From Pseudomonas fluorescens BTP2 a pyoverdin was isolated which contained the so far not encountered Val in its peptide chain. Its structure could be elucidated by chemical degradation and spectroscopic data. [less ▲]

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See detailThe Nucleotide Sequence Of Saccharomyces Cerevisiae Chromosome Vii
Tettelin, H.; Carbone, Mla.; Albermann, K. et al

in Nature (1997), 387(6632),

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