The interaction between Azospirillum brasilense and Bradyrhizobium japonicum modifies the Bradyrhizobium-soybean simbiosis

TORRES, DANIELA; DONADIO, FLORENCIA; LÓPEZ, GASTÓN; NIEVAS, SOFÍA; MORA, VERÓNICA; CASSÁN, FABRICIO

Montevideo

Congreso; XXX Reunión Latinoamericana de Rizobiología. V Conferencia Latinoamericana de Microorganismos Promotores del Crecimiento Vegetal.; 2021

Asociación Latinoamericana de Rizobiología (ALAR)

B. japonicum have beenextensively studied in terms of their symbiotic association with soybean and alternativepractice of N-fertilization. A. brasilense is a plant-growth promoting bacteria that have attracted attention ofresearchers and companies over the last four decades because its capacity topromote plant growth and crop productivity of several plant species, including legumesin combination with rhizobia. The simultaneous inoculation with B. japonicum and A. brasilense has been defined as co-inoculation and considered anextensive practice in South America. In Argentina, most of the commercial productsare formulated with B. japonicum E109(BjE109) and A. brasilense Az39 (AbAz39),two of the most used strains for Agriculture. The main objective of our study was to evaluate and comparedifferent strategies of BjE109 and AbAz39 inoculation and their impact onthe rhizobia-soybean symbiosis. For this purpose, five treatments were considered:(1) uninoculated seeds; (2) inoculated with BjE109;(3) inoculated with AbAz39; (4) simultaneouslyinoculated with BjE109 and AbAz39 and (5) co-inoculated with a mixof both strains. The mix ratio (1:1) was chosen because it expressed thehighest exopolysaccharide (EPS) and biomass productionbesides the highest IAA degradation by BjE109 in culture medium. For each treatment it was evaluated the rhizobia viable cells recoveryfrom inoculated seeds, as well as the symbiosis and plant growth promotionunder both glasshouse and field assays. The interaction between AbAz39 and BjE109 and improvesthe BjE109 capacity to survive onsoybean seeds after inoculation; increase the nodulation and symbiosisparameters as well as the grain yield under field conditions. The AbAz39 capacity to produce active molecules should suggest at least partof the changes observed in B. japonicumbehavior. These results lead us to anew understanding about the use of combined biological products foragriculture.