Distribution of N-Acylhomoserine Lactone-Producing Fluorescent Pseudomonads in the Phyllosphere and Rhizosphere of Potato (Solanum tuberosum L.)

Abstract

Four hundred and fifty nine isolates of fluorescent pseudomonads were obtained from the leaves and roots of potato plants. Of these, 20 leaf isolates and 28 root isolates induced violacein production in two N-acylhomoserine lactone (AHL)-reporter strains-Chromobacterium violaceum CV026 and VIR24. VIR24 is a new reporter strain for long Nacyl-chain-homoserine lactones, which can not be detected by CV026. Thin-layer chromatography revealed that the isolates produced multiple AHL molecules. We compared the 16S rRNA gene sequences of these isolates with sequences from a known database, and examined phylogenetic relationships. The AHL-producing isolates generally separated into three groups. Group I was mostly composed of leaf isolates, and group III, root isolates. Group II comprised both leaf and root isolates. There was a correlation between the phylogenetic cluster and the AHL molecules produced and some phenotypic characteristics. Our study confirmed that AHL-producing fluorescent pseudomonads could be distinguished in the phyllosphere and rhizosphere of potato plants.

Degradation of N-Acylhomoserine Lactone Quorum Sensing Signaling Molecules by Potato Root Surface-Associated Chryseobacterium Strains

“…Previously, we found many AHLproducing and -degrading bacteria to be present on the surface of potato plants. Of 459 isolates of fluorescent pseudomonads obtained from the leaves and roots of potato plants, 48 showed AHL-producing activity (23). Several studies related to the presence of AHL-degrading bacteria have been conducted on potato plants.…”

A Great Leap forward in Microbial Ecology

“…Two signaling systems utilizing distinct N-acylhomoserine lactones (AHLs) which are common among Gram-negative bacteria (146), are the LasR-LasI (las) and RhlR-RhlI (rhl) systems. Another type of signaling molecule is 2-heptyl-3-hydroxy-4-quinolone which is referred to as the Pseudomonas quinolone signal (PQS).…”

The ppuI-rsaL-ppuR quorum-sensing system regulates cellular motility, pectate lyase activity, and virulence in potato opportunistic pathogen Pseudomonas sp. StFLB209

“…6,19) The major phylogenetic group of these pseudomonads isolated from the potato phyllosphere showed a certain degree of similarity to P. cichorii ATCC 10857. 6) P. cichorii has been characterized as a plant pathogenic bacterium.…”

“…These variations are influenced by differences in plant genotypes, growth stages, 2) plant organs, 3) and growth conditions. 4) A good understanding of the factors and mechanisms enabling each microbial habitat to adapt on the plant surface is important for the development of successful biocontrol against plant pathogens, as is a thorough assessment of the characters of each microbial habitat, including production and degradation of AHL quorum-sensing signaling molecules, [4][5][6][7] plant pheromone production, 4,8) carbon source utilization, 9) and biocontrol activity. 10) AHL production is often observed in plant-associated bacteria.…”

“…4,[673][674][675][676][677][678][679][680] the phyllosphere of potatoes collected in Japan. 6) Although all of the strains of the major group of pseudomonads isolated were found to produce AHL, 6) the relationship between AHL-mediated quorum sensing and the expression of virulence factors has not yet been elucidated. In this study, we report the cloning and characterization of AHL-synthase and AHL-receptor genes from one of the bacterial strains from the major group of pseudomonads in potato phyllosphere, Pseudomonas sp.…”