Differentiation of Cannabis subspecies by THCA synthase gene analysis – an overview and update

Abstract

Cannabis Sativa Sativa, known as hemp or industrial Cannabis, is a fast-growing plant, widely used for the production of a variety of commercial items. Cannabis Sativa Indica, or marijuana, is well-known for its psychoactive component THC, a product of spontaneous decarboxylation of THCA, synthesized by the marijuana-specific THCA synthase (THCAS) gene. Marijuana is mainly used for recreational purposes, but, also, it is a subject of drug abuse. Considering that marijuana and hemp could not be reliably differentiated morphologically, several methods have been developed for detecting marijuana for forensic purposes. The common HPLC method is used for qualitative and quantitative detection of THCA, practically exclusively present in marijuana. Knowing that the quantity of THCA largely differs between plants of different ages, male and female, and different parts of plants and that it could be easily degraded in time, chemical detection may not always be the method of choice. So, in cases of suspicious or negative results for THCA content, especially when one could not recognize the source material, or one should decide if it is a marijuana or hemp seed, genetic analysis of the THCAS gene, responsible for the synthesis of THCA, and present exclusively in marijuana, should be considered. Since the year 2006 and the identification of the THCAS gene by Kojoma and co-workers, this type of analysis has been enabled and many methodologies differentiating between THCAS and THCAS–like genes, present in hemp, too, were developed. Research of Laverty and co-workers (2019), was found that THCAS–like gene is a gene for the synthesis of cannabichromenic acid (CBCA), another cannabinoid compound abundant in Cannabis plants. As a result of our work, we provide an algorithm that includes forensic identification of the THCAS gene, which could be helpful in elucidating if the suspected plant material is marijuana or hemp, is it degraded or inhibited, or is it plant at all.