Improvement of soybean nodulation by bacterial exposure to nanoparticles.

DE VALOIS N; GROPPA MD; BENAVIDES MP; ZAWOZNIK MS; IANNONE MF

Jornada; XX Jornadas Anuales de la Sociedad Argentina de Biología (SAB) y XVII Jornadas de la Sociedad Uruguaya de Biociencias (SUB) -; 2018

In the last years, there was a growing interest in the use of nanotechnology products to improve crop production. Since Rhizobium-legume symbiosis is a relevant system in agriculture, the goal of this work was to carry out basic studies to analyze the effects of magnetite nanoparticles (NPs) on soybean-Bradyrhizobium japonicum symbiotic association. Soybean seeds were inoculated with B. japonicum cells (Control: C) or with B japonicum cells exposed during multiplication to 10 ppm of magnetite NPs (BANP). B. japonicum used for inoculation was grown for 5 days in a rotary shaker with or without NPs. CFU were adjusted before inoculation. Seeds were left in contact with bacterial suspensions (C or BANP) for 12 hours. Soybean plants were grown on soil in a growth chamber, with periodic water irrigation, and harvested 20 or 30 days later. Bacterial NPs pretreatment improved the germination rate. Additionally, root and aerial part length and total biomass were significantly greater in BANP plants. In the same way, root surface increased four times and an increment of 13% in chlorophyll content was observed in BANP treatment with respect to controls at any time studied. At 20 days, nodules were present only in BANP treatment. At day 30, leghemoglobin content in the nodules of BANP plants doubled that of the controls. We concluded that incubation of bacteria in the presence of magnetite NPs resulted in improvement of nodulation and biological nitrogen fixation, which was accompanied by greater seedling growth and chlorophyll level. Thus, magnetite NPs could become a good candidate for the design of new products for agricultural use.