Growth promoting activities in copper-resistant AHL-producing bacteria from tomato rhizosphere

ANA CAROLINA LEGUINA; BARRIOS, ANDREA CECILIA; ELISA V. BERTINI; PABLO M. FERNANDEZ; LUCÍA I. CASTELLANO DE FIGUEROA; CARLOS G. NIETO PEÑALVER

Trieste

Workshop; Joint ICGEB-ICTP-APCTP Workshop on Systems Biology and Molecular Economy of Microbial Communities; 2017

International Centre for Genetic Engineering and Biotechnology

Quorum Sensing (QS) systems have animportant role in the rhizosphere dynamic. Cooper contamination could havedetrimental effects on beneficial rhizospheric microorganisms and theirinteractions. The objective of the present work was to characterize plantgrowth promoting activities in copper-resistant bacteria that can produce AHLsand used them as a model for the study of the effect of the metal on theinteractions mediated by QS. Bacterial isolates were obtained from tomatoplants rhizosphere. The production of AHLs by isolates was evaluated. Coppertolerance was assayed and molecular identification of the AHL producingisolates that show the highest resistance to copper was performed. For the characterizationof plant growth promoting activities of the selected strains, the followingassays were carried out: indole acetic acid quantification, phosphatesolubilization, siderophore production, NH3 production, determination ofprotease activity and cellulase activity, catalase test, polyamine productionand evaluation of antagonism with Botrytis cinerea in solid médium. A total of48 isolates were able to produce AHLs. Four bacterial isolates were selectedfor resisting copper concentrations of up to 5 mM. All four belonged to thegenus Pseudomonas. All Pseudomonas spp. strains exhibit several growthpromoting activities and two of them were notable for showing seven of the tenactivities tested. Rhizospere bacteria could improve plant growth andresistance, and their QS systems may have a critical role on therhizobacteria-host plant interaction. Also the resistance to copper of theseisolates will allow the study of the effect of elevated copper concentrationson microbial interactions.