Identification of plant compounds involved in the microbe-plant communication during the coinoculation of soybean with bradyrhizobium elkanii and delftia sp. strain JD2

Abstract

Delftia sp. strain JD2 is a betaproteobacterium characterizedas a plant growth-promoting bacterium with a 'helper' function, enhancing the performance of rhizobial inoculant strainsduring the coinoculation of alfalfa and clover. In this work weanalyzed i) the effect of the coinoculation with Bradyrhizobiumelkanii and Delftia sp. strain JD2 strains on the performance ofsoybean plants and ii) the production of a few secondary plantmetabolites that would explain the positive effect of coinoculation on the growth and development of soybean plants. Theresults showed a beneficial effect of coinoculation on soybeangrowth, nodulation rate, and pulse yield, with the concomitantbenefit for the agricultural economy. In addition, based on ametabolomics approach, we demonstrated that a differentpattern of plant metabolites is being produced at differentstages of plant growth. The new information suggests that thecoinoculation of soybean changes the primary and secondarymetabolism of the plant, including changes in the metabolicstatus of main and secondary nodules within the plant. Therelevance of producing a different pattern of photosyntheticand photoprotective pigments, flavonoids, organic acids, andcarbohydrates are discussed. Finally, we propose that JD2could be used together with bradyrhizobia to manipulate thechemical composition of plant tissues, promoting the nutritional benefits and health of soybean.