Genomic Science Program
U.S. Department of Energy | Office of Science | Biological and Environmental Research Program

Response of Soil Microbial Communities to Nitrogen and Phosphorus Input in Sorghum Field


Busayo J. Babalola1*(, Thomas H. Pendergast1, Sedona M. Spann2, Zsuzsi Kovacs2, Katrien M. Devos1, Jeff Bennetzen3, Nancy C. Johnson2, Y. Anny Chung1


1Department of Plant Biology, University of Georgia–Athens; 2Department of Biological Sciences, Northern Arizona University; 3Department of Genetics, University of Georgia–Athens


The interactions between plants and their microbiomes, specifically arbuscular mycorrhizal fungi (AMF) and nitrogen-fixing bacteria (NFB), play a crucial role in supporting host nutrition, immunity, and development. The project aim is to uncover the genetic factors in sorghum that impact the development and effectiveness of microbial communities in different environmental disturbances. Large-scale farming practices commonly depend on water and chemical fertilizers, neglecting the potential advantages of microbiomes in enhancing plant ability to absorb soil water and nutrients and the current implications of irrigation and the utilization of chemical fertilizers on both the economy and the environment. Through a comprehensive analysis, the project’s main goal is to identify and characterize sorghum genotypes that can enhance crop productivity and resilience by establishing microbial communities to reduce farmers reliance on water and chemical fertilizers.


To address the knowledge gap regarding the influence of nutrient availability on microbiomes in multiple compartment niches (rhizosphere, soil, and root), researchers collected samples from an existing genome-wide association study (GWAS) field experiment to examine the differential response of bacteria versus fungi associated with biofuel sorghum genotypes to nitrogen (N) and/or phosphorus (P) inputs. Further, the team will investigate the mechanisms by which sorghum plants maintain a stable presence of AMF and phosphate solubilizing bacteria (PSB) in their root structures, even when the benefits of this symbiotic relationship for nutrient uptake may be compromised. The project will test three hypotheses.

  1. The N or P inputs will have distinct impacts on the development of soil microbiome, particularly resulting in a decrease in the abundance of NFB (diazotrophs) and P uptake fungi (AMF, edaphophilic), but the root microbiomes will deviate from these trends. The team postulates that these outcomes may result from biotic filtering of the host, where roots separate the assemblage of microbiome communities associated with sorghum roots from the overall soil community.
  2. The co-occurrence networks of AMF and PSB will show higher modularity when P is in limited supply compared to when in luxury supply.
  3. The responses to dual N and P input will be less resistant across different compartments, but the strongest resistance will be observed in the root microbiomes. These findings will provide valuable insights for optimizing microbial communities to improve plant health and productivity in both agricultural and ecological contexts.