Semester
Fall
Date of Graduation
2025
Document Type
Dissertation
Degree Type
PhD
College
Davis College of Agriculture, Natural Resources and Design
Department
Division of Plant and Soil Sciences
Committee Chair
Michael Gutensohn
Committee Member
Vagner Benedito
Committee Member
Yong-Lak Park
Committee Member
Kevin Daly
Committee Member
Nicole Waterland
Abstract
Cannabis sativa produces a diverse array of secondary metabolites—particularly cannabinoids—which have been used by humans for millennia for medicinal, nutritional, and recreational purposes. Despite extensive interest in their therapeutic applications, the biological function of cannabinoids within the plant remains only partially understood. More than 140 cannabinoids have been identified and classified into four structural series: varinol, butol, olivetol, and phorol. While previous research has largely focused on olivetol-series cannabinoids such as CBD and Δ⁹-THC, emerging evidence suggests that cannabinoids across all four series may contribute to defense responses. In this dissertation, we conducted herbivory assays using beet armyworm larvae in combination with metabolomic and transcriptomic analyses to explore the plant’s biochemical response to biotic stress. Larval feeding induced significant upregulation of cannabinoid biosynthesis genes and elevated levels of some of olivetol-, varinol-, butol-, and phorol-series cannabinoids. Moreover, cannabinoid toxicology assay on beet armyworm reveals that some of these upregulated cannabinoids, including Δ⁸/Δ⁹-THCVA, Δ⁸/Δ⁹-THCV, and Δ⁹-THCB, exhibited insecticidal properties, supporting the hypothesis that cannabinoids may function as defense compounds against herbivores.
Building on these findings, a detached-leaf herbivory assay across six cannabis strains demonstrated that specific cannabinoids, notably Δ⁹-THCVA, Δ⁹-THCV, Δ⁹-THCBA, CBCA, and CBLA, showed negative correlations with larval feeding rates, indicating reduced palatability or increased toxicity. These same cannabinoids were upregulated in response to insect damage, further supporting their ecological role in plant defense. Together, these results suggest that cannabinoids have likely evolved as chemical deterrents against biotic stress, revealing a functional dimension to cannabinoid diversity that has been historically overlooked. The insecticidal properties of these naturally occurring compounds also highlight their potential application as environmentally friendly, organic pest management agents.
Given the therapeutic and commercial significance of cannabis, the final component of this dissertation examined the distribution of varinol-, butol-, olivetol-, and phorol-series cannabinoids across different tissues (flowers, leaves, bark, and seeds) and diverse cannabis chemotypes. Our analyses revealed that all four-cannabinoid series were present in varying concentrations across tissues and strains, with certain butol cannabinoids also detected in seeds. Seeds believed to have no cannabinoids as there is no trichome on the seat coat and those studies which have shown cannabinoids in seeds may be due to the physical contamination during harvesting as the seed calyx have glandular trichomes. Our study makes sure to get rid on any physical contamination of cannabinoids and after this we do find cannabinoids in the seed endosperm. Cannabis plant may have translocated the cannabinoids in the seeds may be as a source of energy or the protection to seed as cannabinoids have some sort of antimicrobial properties. Some strains were enriched in varinol or olivetol cannabinoids, while others exhibited broader cannabinoid diversity. These findings indicate that minor cannabinoids—particularly those from the butol and phorol series with high receptor-binding affinities—may modulate the therapeutic properties of cannabis plant.
Recommended Citation
Deo, Bikash Kumar, "Characterization of the cannabinoid and terpene metabolic networks and their regulation in response to biotic stress in industrial hemp" (2025). Graduate Theses, Dissertations, and Problem Reports. 13165.
https://researchrepository.wvu.edu/etd/13165