Nodule Bacteriome As a Driver of Soybean Yield.

The bacterial communities (bacteriome) that inhabit and function as mutualists in the nodules of soybean, a major world-wide crop, are a fundamental determinant of soybean growth and its contributions to global nitrogen and carbon cycles. Unfertilized soybean can derive up to 90% of its nitrogen through bacterial-driven diazotrophy. It was the goal of the research in this study to assess whether different bacterial taxa (e.g. Bradyrhizobia spp.) differ in their soybean growth supportive role, that could then feedback to alter global biogeochemical cycling. Using 16S rRNA and NifH genes, nodule bacteriomes were shown to vary across 9 different cultivars of non-inoculated soybean, and that the variation between cultivars were highly correlated to plant yield. The relative abundances of gene sequences associated with the closest taxonomic match (NCBI), indicated that several taxa were (r= 0.76) negatively (e.g. Bradyrhizobium sp Ec3.3) or (r= 0.84 ) positively (e.g. Bradyrhizobium elkanii WSM 2783) correlated with plant yield. Other taxa, not often associated with nodules, such as Psuedomonas, and Rhodopseudomonas spp. were also prevalent and correlated with plant yield. Soybeans are a sustainable high quality source of non-animal protein, and also serve to support soil organic matter nitrogen for subsequent crops. The study of this important agroecosystem plant and its ability to interact promiscuous soil bacteria are in need of further study to assess potential for management and breeding to support soybean yield.