# Releasing the Full Potential of Cannabis through Biotechnology
###### Abstract
As the second most abundant cannabinoid after THC, CBD gained a growing interest due to its therapeutic potential, especially in treating epileptic seizures, even though its mechanism is not well understood [29]. Since CBD is demonstrated to be an antagonist to CB1 and a partial CB2 agonist, it is identified as a negative allosteric modulator of THC naturally [30; 31]. Recently, the growing interest in the therapeutic properties of cannabinoids has shifted public attitudes [32]. Among all reported cannabis phytochemicals, CBD has therapeutic potential in treating mood disorders, pain, diabetes, neurodegenerative, and central nervous system diseases [33]. Unlike THC which can cause paranoia and memory loss, CBD has been proved highly safe in pharmacological properties [34]. Since there is an increased demand for medical products containing these chemicals, it is imperative to adopt biotechnologies, such as genetic engineering, to generate more varieties of Cannabis with desirable pharmacological properties to better meet the demand [35]. Considering the legal status of this plant, the synthesis of phytocannabinoids in other systems is less problematic, and relative research in heterologous biosynthesis has been going on for decades. [PERSON] et al. engineered yeast strains to produce CBD from galactose, which laid foundation for the large-scale cannabinoid fermentation and enabled the pharmacological study of the cannabinoids in minor amounts [36]. This study promoted the possibility of cannabinoid synthesis using different systems. Recently, another two intermediate compounds (olivetolic acid and cannabinoid acid) have been synthesized using aromatic prepryltransferase in _Nicotiana benthamiana_ and _Saccharomyces cerevisiae_[37]. Although the heterologous biosynthesis succeeded both in microorganism and in planta systems, challenges still need to be addressed to allow large-scale production, such as the high cost compared to agricultural production. Gene editing technology possesses a crucial potential to increase the production of valuable metabolites. This technology has been applied to engineer bacteria or fungi genomes by introducing desired sgRNA fragments with specific promoters or transcriptional regulators for novel functions [38]. As the common substrate to produce cannabinoids, CBGA is produced from the mevalonate-pathway. In comparison to non-edited strains, the mevalonate content in yeast cells can be increased by more than 41-fold using CRISPR [39]. Since [PERSON] et al. established the biosynthetic approach to produce cannabinoid analogues, which demonstrated the potential of microorganism to produce cannabinoids [36], the upregulated mevalonate pathway would provide a great opportunity for large-scale production of major cannabinoids from the simple sugar galactose. Besides, CRISPR can be used to increase the production of desirable Cannabis metabolites while eliminating the synthesis of THCA and other psychedelic compounds [40]. This has been successfully used in fungi. In the modified _Monascus purpreus_ strain KL-001, a dual-plasmid CRISPR/Cas system was designed to remove harmful contaminants formed in the production of Monascus red. The production of Mycotoxin, which caused disease and death in both humans and animals, was suppressed with the deletion of a 15-kb citrinin biosynthetic gene cluster [41]. The cytotoxic effect of cannabinoids is another challenge that needs to be addressed. In suspension-cultured Cannabis cells, treatment with 50 uM CBGA and THCA caused 100% cell death and similar results were observed in tobacco and insect cells treated with CBGA and THCA [42]. Like many other secondary metabolites synthesized in glandular trichomes, cannabinoids act as defense compounds and protect young tissues from predator damages by inducing cell apoptosis processes. Therefore, organisms or plants with storage cavities are appropriate candidates for the mass production of cannabinoids in heterologous systems, such as the glandular trichomes of mint, basil, lavender, oregano, and thymme.