Linking soil health to human health: Arbuscular mycorrhizae play a key role in plant uptake of the antioxidant ergothioneine from soils

Authors: Carrara, Joseph; Lehotay, Steven; Lightfield, Alan; SUN, DONGXIAO - Pennsylvania State University; RICHIE JR, JOHN - Pennsylvania State University; SMITH, ANDREW - Rodale Institute; Heller, Wade

Submitted to: Plants, People, Planet
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2023
Publication Date: 2/21/2023
Citation: Carrara, J.E., Lehotay, S.J., Lightfield, A.R., Sun, D., Richie Jr., J.P., Smith, A.H., Heller, W. 2023. Linking soil health to human health: Arbuscular mycorrhizae play a key role in plant uptake of the antioxidant ergothioneine from soils. Plants, People, Planet. 5:449-458. https://doi.org/10.1002/ppp3.10365.
DOI: https://doi.org/10.1002/ppp3.10365

Interpretive Summary: The amino acid ergothioneine has recently gained attention as an important antioxidant for human health, which has been shown to prevent chronic diseases of the heart and brain. Ergothioneine is known to be produced only by fungi and certain types of bacteria, and humans acquire it exclusively through their diet. Plant-based foods are a major source of ergothioneine; however, plants also don’t synthesize ergothioneine and acquire it from microbial sources in the soil by an unknown mechanism. Based on the recent finding that soil tillage negatively affects the ergothioneine content of crops, and evidence that tillage also reduces Arbuscular Mycorrhizal Fungi (AMF) populations, we hypothesized that AMF play a role in plant uptake of ergothioneine. Using controlled inoculation trials of asparagus, black beans, oats, wheat, and yellow potatoes, we found that AMF inoculation enhanced the ergothioneine content in all crops evaluated. The level of AMF colonization, which varied among inoculation treatments, positively correlated with ergothioneine content, strengthening support for our finding that AMF act as a mediator of plant ergothioneine uptake. These results indicate that farming practices which promote the symbiotic relationship between crops and AMF enhance the nutritional quality of food produced.

Technical Abstract: Purpose: The amino acid ergothioneine has recently gained attention as an antioxidant that may benefit human health. Ergothioneine is produced by fungi and mycobacteria in soils and is acquired only from diet. The mechanism by which ergothioneine is transferred from soil to plant is unknown. Recent work has shown tillage reduces the amount of ergothioneine in crops. As tillage also reduces arbuscular mycorrhizal fungi (AMF) populations, we hypothesized that AMF play a role in plant uptake of ergothioneine from soils. Methods: To test this hypothesis, we grew asparagus, black beans, oats, wheat, and yellow potatoes with a variety of single species and mixed species AMF inocula and compared ergothioneine levels of these plants to plants that were uninoculated. Results: We found that mycorrhizal inoculation enhanced ergothioneine content across all plants. There was a positive correlation between AMF colonization level and plant ergothioneine content. In addition, we found a positive correlation between plant ergothioneine and copper content which suggests that plants may use the former as an antioxidant. Conclusion: AMF appear to be important mediators of plant ergothioneine uptake. We argue that farming practices that promote AMF populations may increase the ergothioneine level of crops in field settings.