CHARACTERIZATION OF NATIVE PHOSPHATE SOLUBILIZING BACTERIA Pseudomonas spp. AND EFFECT OF THEIR INOCULATION ON PLANTS OF AGRICULTURAL INTEREST IN MICROCOSM ASSAY

ANZUAY, MARÍA SOLEDAD; BERNARDI, PAULA ; INTELANGELO, ARIANA ; LUDUEÑA, LILIANA MERCEDES; ANGELINI, JORGE GUILLERMO; TAURIAN, TANIA

Congreso; XVII Congreso Argentino de Microbiología General. Sociedad Argentina de Microbiología General-SAMIGE; 2023

In Argentinian agricultural areas, deficiency of nutrients is one of the most important factors that limit crop production. Within soil bacteria, some of them are capable of exercising beneficial effects on plant growth designated as plant growth promoting bacteria (PGPB). These bacteria can enhance plant growth and protect plants from disease and abiotic stresses. Bacteria belonging to genus Pseudomonas spp. have been extensively analyzed and present numerous plant growth promoting properties. The formulation and field application of biological inoculants is of great importance in sustainable agriculture and the use of native PGPB constitutes an alternative to replace or reduce the use of agrochemicals.The aim of this study was to characterize native bacteria belonging to genus Pseudomonas spp. and analyze the effect of its inoculation on peanut and maize plants in microcosm assay.Properties associated with plant growth promotion in native phosphate solubilizing bacteria Pseudomonas sp. SA-S-7 and Pseudomonas sp. LC-ER-4 were determined: N2 fixing capacity, siderophores and hydrocyanic acid (HCN) production, synthesis of indole acetic acid (IAA) and activity of 1-aminocyclopropane-1-carboxylic acid deaminase (ACC deaminase). For microcosm assays, peanut and maize seedlings grown in individual pots, containing non-sterile soil as a support with low P content, were inoculated with Pseudomonas sp. SA-S-7 or Pseudomonas sp. LC-ER-4. Uninoculated peanut and maize plants and plants inoculated with the commercial strain Pseudomonas fluorescens PMT1 (RIZOFOS-RIZOBACTER) recommended for maize and wheat plants in Argentina, were used as controls. Plants were grown under controlled environmental conditions, watered regularly with water and nutrient solution. Peanut and maize plants were harvested at 45 and 60 days, respectively and aerial and root length, shoot and root dry weight and aerial P content were determined.Results indicated that Pseudomonas sp. SA-S-7 and Pseudomonas sp. LC-ER-4 have N2 fixing capacity, are able to produce IAA and express ACC deaminase activity. In addition, the SA-S-7 strain presented siderophore production. Neither of the native strains presented HCN production.Results showed significant increases of shoot dry weight in peanut plants inoculated with LC-ER-4 strain, compared to control plants. Peanut plants inoculated with the SA-S-7 strain significantly increased aerial P content with respect to the plants without inoculation. In addition, maize plants inoculated with this strain showed significant increases in aerial and root length and in root dry weight compared to uninoculated plants.The native strain Pseudomonas sp. SA-S-7 could be employed in the formulation of biofertilizers for peanut and maize crops. These preliminary results are encouraging since studies of Pseudomonas spp. associated with growth promotion on peanut plants are scarce.