Total THC content in the floral buds collected from plants grown in Miracle-Gro soil outdoors or in the greenhouse was higher than the floral buds collected from plants grown in mine land soil outdoors or in the greenhouse and field conditions. Total THC levels in mine land 1 soil with the Fedora 17 variety remain under the European Economic Community (EEC) legal threshold limit of 0.3%, whereas the Fedora 17 variety in Miracle-Grow indoors is over the legal limit for industrial hemp. Total CBD content in the floral buds grown in mine land 1 soil in both outdoors and in the greenhouse was higher than the floral buds grown in Miracle-Gro in both environmental parameters and in the field, which can be concluded due to the heavy metal stress.
To estimate the alteration of gene expression of hemp in outdoor mine land conditions, a qRT-PCR was performed on the Ferimon variety. Cannabinoid pathway starts with the synthesis of olivetolic acid by tetraketide synthase and olivetolic acid cyclase . Afterwards, olivetolic acid is converted into Cannabigerolic acid (CBGA) by CBGA synthase. Finally, THCA and CBDA are synthesized from CBGA by THCA synthase (THCAS) and CBDA synthase (CBDAS), respectively . In this study, we measured gene expression of five cannabinoid pathway genes above. Notably, Cannabidiolic acid synthase (CBDAS) was expressed 18 times higher in the mine land soil, however there was no significant difference between mine land 1 and Miracle-Gro soil in the tetrahydrocannabinolic acid synthase (THCAS) expression (Fig 3).
– https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0221570Enhanced tolerance of industrial hemp (Cannabis sativa L.) plants on abandoned mine land soil leads to overexpression of cannabinoids