Soil Mineral-Root Interactions Shape Root Development and Secreted Chemicals

The Science                                  

The reactivity of soil minerals plays a critical role in shaping plant growth and root chemical secretion, driving feedback loops in the rhizosphere that influence overall nutrient cycling and plant production. Mineral-driven processes remain poorly understood and are rarely characterized under realistic soil conditions, especially for bioenergy crops grown in diverse field environments. As part of a multi-institutional study, scientists used a tiny device called a RhizoChip to grow industrial hemp plants in a soil-like environment. They found that roots only grew when minerals were present, and the types of chemicals the roots released changed depending on those minerals.

The Impact

Scientists are still learning how plant roots interact with the surrounding soil as a way to enhance plant productivity. To address this knowledge gap, a multi-institutional team of researchers used a new capability called the RhizoChip that mimics real soil in a small, controlled space to study how roots respond to soil in real-time. Industrial hemp was used as the initial test species because hemp is an agronomic crop with growing economic importance, including production of durable and breathable antimicrobial fibers, paper, and as a food supplement. In this work, the team demonstrated that soil mineral particles are not only helpful, they are necessary for hemp roots to propagate and release important chemicals that are important for overall plant growth. 

Summary

In this study, a multi-institutional team of researchers used a novel microfluidic platform, a RhizoChip, to investigate how soil minerals influence root growth and exudate composition in industrial hemp (Cannabis sativa L.). Mineral-driven processes remain poorly understood and are rarely characterized under realistic soil conditions, especially for bioenergy crops grown in diverse field environments. This research incorporated soil-like minerals (kaolinite, potassium feldspar, and biotite) to simulate natural soil conditions more accurately. The team examined the role of minerals in root development and the metabolites produced by these roots. Untargeted metabolomics was used to identify compounds, including amino acids, organic acids, and secondary metabolites. Metabolic analyses were conducted to identify the pathways essential for nutrient metabolism and cellular function using KEGG pathway mapping. These identified pathways are crucial for nitrogen utilization and protein synthesis, which are essential for plant growth and stress tolerance. Spatial mapping of metabolites was achieved through the use of matrix-assisted laser desorption/ionization mass spectrometry imaging, performed at the Environmental Molecular Sciences Laboratory, a Department of Energy, Office of Science user facility. The team observed that hemp roots only grew in microfluidic chips containing soil minerals, with the presence of minerals also significantly altering root exudate composition. These findings suggest that mineral availability may act as a developmental trigger, potentially linked to nutrient-sensing or stress-signaling pathways. While the exact molecular mechanisms remain to be fully elucidated, this study lays the groundwork for future research into how specific minerals activate metabolic pathways that enhance nutrient uptake, stress resilience, and microbial interactions in the rhizosphere. The research demonstrates the feasibility of using microfluidic devices to study economically important plants under realistic soil conditions, highlighting the critical role of minerals in shaping root chemistry and offering new hypotheses for advancing bioenergy crop productivity.

Contacts

Idowu Atoloye, Alcorn State University: iatoloye@alcorn.edu 

Arunima Bhattacharjee, EMSL: arunimab@pnnl.gov

Daisy Herrera, EMSL: daisy.herrera@pnnl.gov 

Funding

This work was supported by an Exploratory Research award from the Environmental Molecular Sciences Laboratory, a Department of Energy Office of Science user facility sponsored by the Biological and Environmental Research program. Additional support was provided by an Evans Allen Grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture.

Publication 

I. Atoloye, et al. “Insight into industrial hemp (Cannabis sativa L.) root exudation composition in a simulated soil environment: a rhizosphere-on-a-chip study.” Rhizosphere 34, 101099 (2025). [DOI: 10.1016/j.rhisph.2025.101099]