Sequence heterogeneity of cannabidiolic- and tetrahydrocannabinolic acid-synthase in Cannabis sativa L. and its relationship with chemical phenotype

SNPs in the sequence of THCA- and CBDA-synthases explain the variability in chemotype in Cannabis sativa L. [Display omitted] •Chemotypical variation in Cannabis for cannabinoid content and composition is very high.•Variation in mutual ratios of THC, CBG and CBD is due to differential efficiency of cannabinoid synthases.•SNPs were identified in THCAS and CBDAS sequences of Cannabis germplasm.•Aminoacid substitutions crucial for enzyme functionality were identified.•Phylogenetic relationships between the cannabinoid synthases THCAS and CBDAS are inferred. Sequence variants of THCA- and CBDA-synthases were isolated from different Cannabis sativa L. strains expressing various wild-type and mutant chemical phenotypes (chemotypes). Expressed and complete sequences were obtained from mature inflorescences. Each strain was shown to have a different specificity and/or ability to convert the precursor CBGA into CBDA and/or THCA type products. The comparison of the expressed sequences led to the identification of different mutations, all of them due to SNPs. These SNPs were found to relate to the cannabinoid composition of the inflorescence at maturity and are therefore proposed to have a functional significance. The amount of variation was found to be higher within the CBDAS sequence family than in the THCAS family, suggesting a more recent evolution of THCA-forming enzymes from the CBDAS group. We therefore consider CBDAS as the ancestral type of these synthases.