The B1080B1192 molecular marker identifies hemp plants with functional THCA synthase and total THC content above legal limit.
In Cannabis sativa L. the presence of delta 9-tetrahydrocannabinolic acid (THCA) above legal limit is a challenging issue that still restricts the industrial exploitation of this promising crop. In recent years, the interest of entrepreneurs and growers who see hemp as a dynamic and profitable crop was joined by the growing knowledge on C. sativa genetics and genomics, accelerated by the application of high throughput tools. Despite the renewed interest in the species, much remains to be clarified, especially about the long-standing problem of THCA in hemp inflorescences, which could even result in the seizure of the whole harvest. Although several hypotheses have been formulated on the accumulation of this metabolite in industrial varieties, none is conclusive yet. In this work, individuals of a population of the hemp cultivar FINOLA obtained from commercial seeds were investigated for total THC level and examined at molecular level. A marker linked to THCA synthase was found at a high incidence in both male and female plants, suggesting a considerable genetic variability within the seed batch. Full-length sequences encoding for putatively functional THCA synthases were isolated for the first time from the genome of both female and male plants of an industrial hemp variety and, using transcriptional analysis, the THCA synthase expression was quantified in mature inflorescences of individuals identified by the marker. Biochemical analyses finally demonstrated for these plants a 100% association between the predicted and actual chemotype.