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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Production Systems Research » Research » Publications at this Location » Publication #355729
Title: Plant microbiome-dependent immune enhancing action of Echinacea purpurea is enhanced by soil organic matter content

Author
item HARON, MONA - University Of Mississippi
item Tyler, Heather
item CHANDRA, SUMAN - University Of Mississippi
item MORAES, RITA - University Of Mississippi
item JACKSON, COLIN - University Of Mississippi
item PUGH, NIRMAL - University Of Mississippi
item PASCO, DAVID - University Of Mississippi

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2018
Publication Date: 1/15/2019
Citation: Haron, M.H., Tyler, H.L., Chandra, S., Moraes, R.M., Jackson, C.R., Pugh, N.D., Pasco, D.S. 2019. Plant microbiome-dependent immune enhancing action of Echinacea purpurea is enhanced by soil organic matter content. Scientific Reports. 9:136.

Interpretive Summary: Echinacea purpurea is an herbal supplement that has become popular in the United States as a natural preventative and treatment for upper respiratory tract infections due to its ability to stimulate the immune system. However, there is a lot of variation in the level of immune stimulating activity seen between different batches of Echinacea plant material. Prior research has found that cell wall components of bacteria colonizing E. purpurea plants are responsible for the majority of its immune stimulating activity, and much of the variation between Echinacea batches is due to differences in the amount and type of bacteria that colonize these plants. Scientists at the University of Mississippi in Oxford and the USDA-ARS Crop Production Systems Research Unit in Stoneville, MS conducted an experiment to determine if immune stimulating activity and bacterial community composition are affected by different soil conditions (organic matter, nitrogen, moisture content) that E. purpurea plants are grown under. A change in soil organic matter content from 5.6% to 67.4% led to a 4.2-fold increase in the immune stimulating response. Shifts in the plant-associated bacterial community were also observed in response to changes in soil organic matter. These results indicate that increasing soil organic matter can be used as a way to reliably produce Echinacea plant material with higher immune stimulating activities.

Technical Abstract: We previously demonstrated that extracts from Echinacea material varied substantially in their ability to activate macrophages in vitro and that this variation was due to differences in their content of bacterial components. The purpose of the current study was to identify soil conditions (organic matter, nitrogen, and moisture content) that alter the macrophage activation potential of E. purpurea and determine whether these changes in activity correspond to shifts in the plant-associated bacterial community. Increased levels of soil organic matter significantly enhanced macrophage activation exhibited by the root extracts of E. purpurea (p<0.0001). A change in soil organic matter content from 5.6% to 67.4% led to a 4.2-fold increase in the macrophage activation potential of extracts from E. purpurea. Bacterial communities also differed significantly between root materials cultivated in soils with different levels of organic matter (p<0.001). These results indicate that the level of soil organic matter is an agricultural factor that can alter the bacterial microbiome, and thereby the activity, of E. purpurea roots. Since ingestion of bacterial preparation (e.g., probiotics) is reported to impact human health, it is likely that the medicinal value of Echinacea is influenced by cultivation conditions that alter its associated bacterial community.