PSEUDOMONAS PUTIDA KT2440 AS A PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) UNDER SALINITY CONDITIONS

STEFANIE BERNARDETTE COSTA GUTIERREZ; MARÍA CAROLINA DEL VALLE CARAM DI SANTO; ANA MARÍA ZENOFF; PAULA ANDREA VINCENT ; MANUEL ESPINOSA URGEL ; RICARDO EZEQUIEL DE CRISTÓBAL

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

The aim of this work was to study the role of Pseudomonas putidaKT2440 as a PGPR under saline soils. A P. putida KT2440 mutant(Mut11), which was affected in the LPS synthesis and characterizedin our laboratory as a low salinity tolerance strain, was also evaluated. This analysis could allow us to have an insight in which is themechanisms used by P. putida KT2440 for this salt tolerance. To thisaim, plants growth promoting properties such as indol acetic acidproduction (IAA), phosphate solubilization and siderophore synthesis of both strains were evaluated under saline (0.5 M NaCl) andnon saline conditions (control). Additionally, seed germination andgrowth promotion of soybean and corn were assayed in saline soils.Both strains exhibited plant growth promoting properties, showingsimilar activities in phosphate solubilization and IAA production under the analyzed conditions, suggesting that they were not affectedby salt (p>0.05). Under saline conditions, the siderophore synthesisof both strains was significantly affected: the wild type strain exhibited a smaller halo than in the control, while no activity was detectedin the mutant (p≤0.05).Seeds inoculated with the wild type showed longer roots andstems than those of uninoculated seeds (p≤0.05), demonstratingthe plant growth promoting effect of P. putida KT2440 under salinityconditions. Meanwhile, seeds inoculated with Mut11 displayed reduced effects on the growth promotion activity than those treated withthe wild type (p≤0.05). Based on these results we evidenced thatthe mutation apparently is not only important for bacterium salinitytolerance, but it is also involved in the PGPR effect under salinityconditions in soybean and corn.This study showed that P. putida KT2440 strain is a useful PGPRin the tested conditions and also suggested that LPS are relevantfor the tolerance to the salinity. This data provides new informationon the KT2440 strain adaptation in response to saline environment.Keywords: Pseudomonas putida KT2440, PGPR, Salinity stress,Lipopolysaccharides