CONICET | Buscador de Institutos y Recursos Humanos

Quorum Sensing (QS) systems have an important role in the rhizosphere dynamic. Cooper contamination could have detrimental effects on beneficial rhizospheric microorganisms and their interactions. Te objective of the present work was to characterize plant growth promoting activities in copper-resistant bacteria that can produce AHLs and used them as a model for the study of the effect of the metal on the interactions mediated by QS.Bacterial isolates were obtained from tomato plants rhizosphere. Te production of AHLs by isolates was evaluated. Copper tolerance was assayed and molecular identification of the AHL producing isolates that show the highest resistance to copper was performed. For the characterization of plant growth promoting activities of the selected strains, the following assays were carried out: indole acetic acid quantification, phosphate solubilization, siderophore production, NH3 production, determination of protease activity and cellulase activity, catalase test, polyamine production and evaluation of antagonism with Botrytis cinerea in solid médium. A total of 48 isolates were able to produce AHLs. Four bacterial isolates were selected for resisting copper concentrations of up to 5 mM. All four belonged to the genus Pseudomonas. All Pseudomonas spp. Strains exhibit several growth promoting activities and two of them were notable for showing seven of the ten activities tested. Rhizospere bacteria could improve plant growth and resistance, and their QS systems may have a critical role on the rhizobacteria-host plant interaction. Also the resistance to copper of these isolates will allow the study of the effect of elevated copper concentrations on microbial interactions.