CBDA synthase (CBDAS) is the oxidocyclase enzyme that converts CBGA into CBDA. Taura and colleagues characterised it in 2007 and described it as the chemotype-determining enzyme in fibre-type cannabis. It sits in the same genomic region as THCA synthase and competes for the same CBGA pool.
In practice
Hemp-type and CBD-type plants carry functional CBDAS and typically non-functional or absent THCAS. Crossing a THC-type plant with a CBD-type plant produces F1 offspring that are usually balanced (roughly 1:1), and an F2 that segregates into THC-type, balanced and CBD-type plants. Real ratios drift from textbook Mendelian numbers because the synthase region contains several linked gene copies and some partially active alleles. Even CBD-dominant plants produce a little THCA, because CBDAS isn't perfectly specific; that matters for anyone growing hemp under a THC limit.
Don't confuse with
- THCA synthase: the competing enzyme.
- CBD: the neutral form, made later by decarboxylation.
- CBGA: the substrate, not the enzyme.
CBGA (cannabigerolic acid) is the precursor cannabinoid that the plant converts into THCA, CBDA or CBCA, formed by joining olivetolic acid to geranyl pyrophosphate.CBDA (cannabidiolic acid) is the acid cannabinoid made by CBDA synthase from CBGA; it dominates hemp-type and CBD-type cannabis and decarboxylates to CBD.THCA synthase is the trichome enzyme that converts CBGA into THCA; which alleles of its gene a plant carries largely decides whether it is THC-dominant.F1 is the first generation of offspring from crossing two parents; if the parents are inbred and different, F1 plants are uniform and often show hybrid vigour.THCA (tetrahydrocannabinolic acid) is the acid cannabinoid that drug-type cannabis makes in its trichomes; heat or time decarboxylates it into THC, losing about 12% of its mass.Hemp is cannabis grown for fibre, seed or other uses and, in many laws, defined as Cannabis sativa with no more than 0.3% THC by dry weight.THC (Δ9-tetrahydrocannabinol) is the neutral, decarboxylated cannabinoid mainly responsible for cannabis's reported intoxicating effects; the living plant makes it almost entirely as THCA.CBD (cannabidiol) is a non-intoxicating neutral cannabinoid formed when CBDA decarboxylates; hemp-type and CBD-dominant cannabis make it mainly as CBDA in their trichomes.The chemotype ratio is the balance of a plant's main cannabinoids, usually THC to CBD, classing plants as type I (THC-dominant), II (mixed), III (CBD-dominant), IV (CBG) or V (near-zero).
