Influence of Fungicide Application on Rhizosphere Microbiota Structure and Enzymes in Diverse Cannabinoid-Rich Hemp Cultivars

Authors: XU, JUNHUAN - Alabama State University; KNIGHT, TYSON - Alabama State University; BOONE, DONCHEL - Alabama State University; SALEEM, MUHAMMAD - Alabama State University; FINLEY, SHEREE - Alabama State University; GAUTHIER, NICOLE - University Of Kentucky; AYARIGA, JOSEPH - Alabama State University; AKINRINLOLA, RUFUS - University Of Tennessee; PULKOSKI, MELISSA - North Carolina State University; BRITT, KADIE - Virginia Polytechnic Institution & State University; TIGIST, TOLOSA - University Of Maryland Eastern Shore (UMES); ROSADO-RIVERA, YARA - North Carolina State University; IDDRISU, IBRAHIM - Alabama State University; THWEATT, IVY - Alabama State University; LI, TING - Alabama State University; ZEBELO, SIMON - University Of Maryland Eastern Shore (UMES); BURRACK, HANNAH - North Carolina State University; THIESSEN, LINDSEY - US Department Of Agriculture (USDA); Hansen, Zachariah; BERNARD, ERNESET - University Of Tennessee; KUHAR, THOMAS - Virginia Polytechnic Institution & State University; SAMUEL-FOO, MICHELLE - Alabama State University; AJAYI, OLUFEMI - Alabama State University

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2024
Publication Date: 5/28/2024
Citation: Xu, J., Knight, T., Boone, D., Saleem, M., Finley, S., Gauthier, N., Ayariga, J., Akinrinlola, R., Pulkoski, M., Britt, K., Tigist, T., Rosado-Rivera, Y., Iddrisu, I., Thweatt, I., Li, T., Zebelo, S., Burrack, H., Thiessen, L., Hansen, Z.R., Bernard, E., Kuhar, T., Samuel-Foo, M., Ajayi, O. 2024. Influence of fungicide application on rhizosphere microbiota structure and enzymes in diverse cannabinoid-rich hemp cultivars. International Journal of Molecular Sciences. 25(11):5892. https://doi.org/10.3390/ijms25115892.
DOI: https://doi.org/10.3390/ijms25115892

Interpretive Summary: Interest in soil health, and specifically soil microbial activity and diversity, has increased in recent years as our understanding of their critical role in plant and ecosystem functioning has grown. This coincides with an increase in industrial hemp acreage (Cannabis sativa L.) in the U.S., where little is known about the influence of hemp varieties and the use of fungicides on hemp rhizosphere microbial communities. To address this knowledge gap, rhizosphere soil samples were collected from four hemp varieties treated with and without fungicides. DNA was extracted from the samples to assess microbial diversity and abundance, and soil enzymatic activity was analyzed. Some microbial phyla, such as Archaea and Rokubacteria, were increased in samples treated with fungicides, while others, such as Proteobacteria and Gemmatimonadetes, were decreased. Additionally, hemp variety significantly impacted microbial diversity and abundance. Fungicide treatments decreased soil enzymatic activity across all hemp varieties. Results indicate that grower practices significantly influence soil microbial diversity and abundance in field-grown hemp, which may impact crop and ecosystem health and functioning.

Technical Abstract: Microbes and enzymes play essential roles in soil and plant rhizosphere ecosystem function. However, fungicides and plant genetics may impact the diversity and abundance of bacteriome structure and enzymatic activities in the plant rhizosphere. In this study, we collected soil samples around the rhizosphere of four Cannabis sativa cultivars (Otto II, BaOx, Cherry Citrus, and Wife) with three different treatments (natural infection, fungal inoculation, and fungicide-treated). DNA was extracted from the samples, 16S rDNA was sequenced, and data were analyzed for diversity and abundance among different fungicide treatments and hemp cultivars. Fungicide significantly impacted the diversity and abundance of the hemp rhizosphere bacteriome structure. The abundance of the phyla Archaea and Rokubacteria were substantially increased. In contrast, the abundance of the phyla Proteobacteria and Gemmatimonadetes were substantially decreased in treatments with fungicides compared to those without fungicides in the four hemp cultivars. In addition, hemp cultivars affected the diversity and abundance of the rhizosphere bacteriome structure. Cultivar Cherry Citrus was found to have less effect on the diversity and abundance of the hemp rhizosphere bacteriome structure compared to the other three hemp cultivars (Otto II, BaOx, and Wife). Moreover, fungicide treatment affected enzymatic activities in the hemp rhizosphere. The application of fungicides resulted in a significant decrease in enzyme abundance across all four hemp cultivars, in contrast to non-application of fungicides. Enzymes such as dehydrogenase, dioxygenase, hydrolase, transferase, oxidase, carboxylase, and peptidase significantly decreased in hemp rhizosphere treated with fungicides compared to those not treated with fungicides in the four hemp cultivars. These enzymes may be involved in the function of metabolizing organic matter and degrading xenobiotics. The ecological significance of these findings lies in the recognition that fungicides impact enzymes, bacteriome structure, and the overall ecosystem within the hemp rhizosphere.