Nod factors (NF) are molecules produced by rhizobia which are involved in the N2-fixing symbiosis with legume plants, enabling the formation of specific organs called nodules. Under drought conditions, nitrogen acquisition by N2-fixation is depressed, resulting in low legume productivity. In this study, we evaluated the effects of NF supply on nitrogen acquisition and on cytokinin biosynthesis of soybean plants grown under drought. NF supply to water stressed soybeans increased the CK content of all organs. The profile of CK metabolites also shifted from t-Z to cis-Z and an accumulation of nucleotide and glucoside conjugates. The changes in CK coincided with enhanced nodule formation with sustained nodule specific activity, which ultimately increased the total nitrogen fixed by the plant.
Keywords: Agroecology; Glycine max; N2-fixation; cytokinins; drought; legume; nodulation factor; nodules; symbiosis.