Gluconacetobacter diazotrophicus PAL5 possesses an active quorum sensing regulatory system

Abstract

The endophytic bacterium Gluconacetobacter diazotrophicus colonizes a broad range of host plants. Its plant growth-promoting capability is related to the capacity to perform biological nitrogen fixation, the biosynthesis of siderophores, antimicrobial substances and the solubilization of mineral nutrients. Colonization of and survival in these endophytic niche requires a complex regulatory network. Among these, quorum sensing systems (QS) are signaling mechanisms involved in the control of several genes related to microbial interactions, host colonization and stress survival. G. diazotrophicus PAL5 possesses a QS composed of a luxR and a luxI homolog, and produces eight molecules from the AHL family as QS signals. In this report data are provided showing that glucose concentration modifies the relative levels of these signal molecules. The activity of G. diazotrophicus PAL5 QS is also altered in presence of other carbon sources and under saline stress conditions. Inactivation of the QS system of G. diazotrophicus PAL5 by means of a quorum quenching strategy allowed the identification of extracellular and intracellular proteins under the control of this regulatory mechanism.

Anatomical and Biochemical Changes Induced by Gluconacetobacter diazotrophicus Stand Up for Arabidopsis thaliana Seedlings From Ralstonia solanacearum Infection

“…bacterium can promote plant growth through different mechanisms that include the biological fixation of nitrogen, the secretion of phytohormones, the solubilization of mineral nutrients, and antagonism toward phytopathogens (Eskin et al, 2014). During the last decades, several studies have tried to identify genes and regulatory proteins involved in the plant-G diazotrophicus association (dos Santos et al, 2010;Lery et al, 2011;Galisa et al, 2012;Bertini et al, 2014). However, many of the crops of agronomic interest are slow-growing species with a complex genome, and often their large size hinder their growth in greenhouses under controlled conditions, which limits the detailed molecular characterization of the plant-bacteria interaction.…”

Nitrogen fixing bacteria in the family Acetobacteraceae and their role in agriculture

“…. By cDNA‐AFLP analysis, some plant genes (using leaf tissue) involved in biocontrol activity was identified . These results indicate that inoculation stimulates genes involved in plant defense such as genes controlling the ethylene defense pathway.…”

“…The genome size is in the average of others AAB genome already published . Further studies of this microorganism functional genomics have been underway by several researchers group and are leading to a comprehension of the role of its gene contents to its general metabolism, nitrogen fixation, and others plant growth mechanisms . In addition, several mutants have already been obtained and used for functional genomic characterization .…”

Endophytic colonization of Arabidopsis thaliana by Gluconacetobacter diazotrophicus and its effect on plant growth promotion, plant physiology, and activation of plant defense

“…During the last decades, several studies have attempted to identify genes and proteins regulated during G. diazotrophicus-plant associations (dos Santos et al 2010;Lery et al 2011;Galisa et al 2012;Bertini et al 2014). However, most of agronomical relevant plants are slow-growing species with a complex genome, and whose large size hinders cultivation under controlled environment, which limits the detailed molecular characterization of plant-bacteria interaction.…”