Cannabis Varieties Can Be Distinguished by Achene Shape Using Geometric Morphometrics

Introduction: Cannabis plant uses are widespread across human cultures. The current tendency is to classify Cannabis varieties into chemovars upon their chemical fingerprint, mainly cannabinoids and terpenoids content. The identification of chemovars has important medical implications; however, their pharmacological characterization is costly and time consuming. The goal of this study was to assess whether achene shape variation could be related to Cannabis varieties with contrasting cannabinoid concentrations, as a first approach to chemovar identification.

Methods: We used two-dimensional geometric morphometrics (GM) of the achenes and multivariate statistical analysis. We used achenes from five varieties, two from Type II chemotype (expressing both tetrahydrocannabinol [THC] and cannabidiol [CBD]), two Type I (THC-only), and one Type III (CBD-only).

Results: The achenes from the different chemotypes were clearly distinguishable. No significant differences between varieties from the same chemotype were observed. The varieties with high THC concentration (Type I) were rounded and bigger, whereas achene from varieties containing only CBD (Type III) had a slender shape with smaller size.

Conclusion: Achene shape variation is a potential biomarker of cannabinoid content in the plant flowers. Further studies are needed to confirm the suitability of GM methods for high-throughput screening of Cannabis cultivars, including larger diversity of varieties, and taking into account growth conditions, which can also influence plant chemical fingerprint.