Exploring the molecular mechanisms of glandular trichome development and cannabinoid biosynthesis in Cannabis sativa

Cannabinoids are a group of commercially valuable compounds,
such as cannabidiolic acid, cannbigerolic acid et al, made primarily in
cannabis female flower trichomes. Therefore, Cannabis sativa would be a great
model plant to study glandular trichome initiation and development. There is no
published study up to now on trichome development in cannabis at the molecular
level, and no genes responsible for trichome initiation have been
characterized. Our lab is mainly interested in the molecular mechanisms of glandular
trichome development and the regulation of genes involved in cannabinoid
biosynthesis. We have identified transcription factors (TFs) that could
potentially regulate glandular trichome initiation and genes for cannabinoid
biosynthesis. Our preliminary results have shown that the expression of two of
the TFs increases with the maturity of flowers, which also coordinates the
development of trichomes as the flower matures. The expression of the two TFs
also correlates with the production of cannabinoids, indicating that they are
playing important roles in trichome development. Our work on the cannabinoid
biosynthesis genes showed a similar expression pattern, indicating that
trichome development is critical for cannabinoid production. Responsive elements
that may be regulated by plant hormones jasmonic acid or salicylic acid are
also found in the promoter regions of cannabinoid biosynthetic genes. We
further identified several TFs, including genes from the MYB and WRKY families,
using trichome RNAseq datasets. Both MYB and WRKY family members have been
shown to regulate genes involved in secondary metabolite biosynthesis. Promoter
analysis of the genes showed binding sites of either MYB or WRKY TFs,
suggesting the regulation of these genes by the TFs. Our findings will advance
the understanding of cannabinoid biosynthesis and provide insights on the
improvement of cannabinoid production.