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

Assessing the Effect of Nitrogen and Phosphorus Fertilization on Root-Microbial Communities and Yield Response in Sorghum bicolor

Authors:

Philip Brailey-Jones1* (philip.braileyjones@uga.edu), Thomas H. Pendergast IV2,3,4, Ashton K. Brinkley1, Sarah R. Mondibrown1, Ndenum S. Shitta1, Katrien M. Devos2,3,4, Jeffrey L. Bennetzen1

Institutions:

1Department of Genetics, University of Georgia–Athens; 2Department of Plant Biology, University of Georgia–Athens; 3Department of Crop and Soil Sciences, University of Georgia–Athens; 4Institute of Plant Breeding, Genetics, and Genomics, University of Georgia–Athens

Goals

This project is designed to identify sorghum genetic factors that drive the formation and function of microbial communities to increase sorghum biomass yield under different environmental conditions. The team will find and characterize sorghum genes/genotypes that can determine optimal crop productivity and durability by creating microbial communities that minimize the need for fertilizer, water, and other inputs.

Abstract

Plant-microbial interactions play an important role in the success of a plant through processes shaping survival, fitness, and crop yield. The extent to which plants benefit from or are negatively affected by their microbial associations is driven by host and microbial genetics, environmental context, and the interaction between these three contributing factors. As part of a larger research project directed at maximizing the biomass yield of Sorghum bicolor through understanding arbuscular mycorrhizal fungal (AMF) interactions with their host plant, researchers examined in situ responses in a diverse sorghum Bioenergy Association Panel to factorially manipulated nitrogen (N) and phosphorus (P) treatments (Brenton et al. 2016). In 2022, 337 sorghum genotypes were grown across 12 blocks (four fertilizer treatments, three replicate blocks) in a previously fallow field in Watkinsville, GA. Roots were harvested for microbial community analysis after 8 weeks of in-field growth, and aboveground biomass, lodging, and tiller traits were recorded after 5 months.

As expected, strong effects of genotype were found on biomass. N and P treatments, alone, were associated with a minor yet significant reduction in biomass relative to unfertilized controls whereas the combined N and P treatment did not affect yields. Using a subset of three sorghum genotypes with contrasting yield responses across the unfertilized and combined N and P fertilized plots, root-colonizing bacterial and fungal communities were assessed through whole-genome shotgun and targeted amplicon sequencing. As with the aboveground biomass response, there was no observable shift in microbial community composition associated with combined N and P fertilization. The three chosen genotypes also exhibited low intergenotype variability and high intragenotype variability, with individual replicated blocks and therefore field location being the major contributing factor to community composition. Post-harvest N and P soil contents were similar between treatments, though this may be a function of plant nutrient uptake that will be further elucidated by plant nutrient content analysis.

References

Brenton, Z. W., et al. 2016. “A Genomic Resource for the Development, Improvement, and Exploitation of Sorghum for Bioenergy,” Genetics 204(1), 21–33.

Funding Information

This research was supported by the US. DOE (20000-12100-192401JB-61001).