Synthesis of quorum sensing signals by diazotrophs from the rhizosphere of strawberry plants

NIETO PEÑALVER CG; BICHARA L; CASTELLANOS DE FIGUEROA, LUCÍA INÉS; DÍAZ RICCI JC

Puerto Madryn, Chubut, Argentina

Congreso; 46th Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

In the rhizosphere, interactions occur with both pathogenic and beneficial microorganisms. The latter group can stimulate plant growth by mean of phytohormone production, direct antagonism of pathogens or induction of systemic resistance in the plant. Quorum sensing (QS) systems from non symbiotic diazotrophic bacteria may play a role in the interactions with strawberry plants and with other organisms. The objective of this work was the characterization of N-acylhomoserine lactones (N-AHLs) produced by free living nitrogen fixing bacteria associated to roots of Fragaria ananassa Duch. cv. Camarosa. Strains were isolated and purified in nitrogen free semisolid media. Extracts were prepared with acidified ethyl acetate and samples were analyzed by TLC. Chromobacterium violaceum Vir07, Agrobacterium tumefaciens NTL4 (pCF218 pCF372) and Pseudomonas putida F117 (pKR-C12) were utilized as biosensor strains for the detection of QS molecules. Nonsymbiotic diazotrophic bacteria producing QS molecules could be isolated from roots of strawberry plants. Production of short chain N-AHLs was detected in all strains. Only one strain produced long chain N-AHLs. Although biosynthesis of QS molecules is not widely distributed in diazotrophic strains from strawberry roots,secretion of short chain QS molecules seem to play a key role as signaling molecules.