Plant growth promotion and siderophore production by a Lotus tenuis endophytic P. fluorescens strain

CASTAGNO LN; RUIZ OA; ESTRELLA MJ

Congreso; 48th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2012

Phosphate (P)-solubilizing bacteria constitute an important group of microorganisms able to improve plant growth and development. Growth promotion through increased P uptake is mediated by bacterial secretion of organic acids and is often combined with the production of other metabolites, such as siderophores, which play a role in biological control of soilborne phytopathogens. Siderophores are low-molecular-weight, Fe-chelating ligands synthesized by microorganisms that help a particular microorganism to compete effectively against other organisms for available Fe, restricting their growth. Furthermore, siderophores are beneficial to plants by solubilizing iron otherwise unavailable for the plant.In this work, the isolate P. fluorescens M25 promoted L. tenuis growth both in vitro and in microcosm experiments. On the other hand, this isolate was resistant to a large group of antibiotics and produced siderophores under Fe-limiting conditions. Interestingly, these siderophores are similar to those produced by the Lotus pathogen P. syringae DC3000. Our results suggest that P. fluorescens M25 could promote plant growth under P- and Fe-limiting conditions such as restrictive alkaline soils that can be colonized by L. tenuis. Addittionally, this strain could antagonize L. tenuis pathogens by restricting their growth through the production of siderophores and other biocontrol metabolites.