ISOLATION AND CHARACTERIZATION OF NATIVE BACTERIA SYMBIONISTS OF MEDICAGO SATIVA IN SOILS OF THE SEMI-ARID PAMPEANA REGION

COLLA C.; DESUQUE J.; BROTO CHIATTELLINO A; LOYOLA M; GARCIA P; CASTAÑO C; LORDA G; CASTAGNO LN; PAGLIERO F

Congreso; XLI Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2023

Soils of the Semi-arid Pampas Region in Argentina present limitations for agricultural production, being nitrogen and water availability the most significant constraints. Despite this, recently, there has been a shift in crop cultivation towards regions with less fertile soils. This situation has led to the intensive use of fertilizers and the erosion of the fertile soil layer. In this context, microbial biofertilizers, as a partial alternative to the use of chemical fertilizers, have become of great importance. One crop that has expanded its cultivation in the region for forage production is alfalfa, which establishes a symbiotic relationship with Ensifer meliloti. Commercial inoculants Recommended for this crop are formulated with the Ensifer meliloti B399 strain. The objective of this study was to obtain native strains better adapted to the region, capable of nodulating and efficiently fixing nitrogen, for use in the formulation of regional inoculants. Native strain isolations were conducted from nodules of alfalfa plants cultivated in the region of interest. Characterization of the strains present in the nodules from these trials using BOX-PCR revealed the presence of eight different native strains apart from Ensifer meliloti B399, capable of nodulating alfalfa and in whichthe nodC gene could be amplified. Kinetic characterization and infectivity tests on plants were conducted for each isolation. Two of them exhibited higher nodulation capacity and showed no differences in efficiency compared to the recommended strain, while in the remaining isolations, no differences were found compared to the control. These isolated microorganisms will be evaluated in non-sterile microcosm trials with the aim of considering their use in inoculants for crops in the region.