Delineating the genetic regulation of cannabinoid biosynthesis during female flower development in Cannabis sativa

Abstract

SUMMARYCannabinoids are predominantly produced in the glandular trichomes on cannabis female flowers. There is little known on how cannabinoid biosynthesis is regulated during female flower development. We aim to understand the rate-limiting step(s) in the cannabinoid biosynthetic pathway.We investigated the transcript levels of cannabinoid biosynthetic genes as well as cannabinoid contents during 7 weeks of female flower development. We demonstrated that the enzymatic steps for producing CBG, which involve genes GPPS, PT and OAC, could be rate limit cannabinoid biosynthesis. Our findings further suggest that cannabinoid synthases, CBDAS and THCAS in a hemp and medical marijuana variety respectively, are not critical for cannabinoid biosynthesis. The cannabinoid biosynthetic genes are generally upregulated during flower maturation, which indicate glandular trichome development.MeJA can potentially increase cannabinoid production. We propose that biweekly application of 100 μM MeJA staring from flower initiation would be efficacious for promoting cannabinoid biosynthesis.Our findings suggest that the step of CBG production could rate limit the terminal cannabinoid biosynthesis. In addition, different cannabis varieties demonstrated discrete transcriptional regulation of cannabinoid biosynthetic genes.

Overexpression of CsMIXTA, a Transcription Factor from Cannabis sativa, Increases Glandular Trichome Density in Tobacco Leaves

“…The results showed that CsMIXTA was significantly upregulated in week 5 and reduced thereafter ( Figure 1 B). CsMIXTA showed a similar expression pattern to that of the enzymes in the cannabinoid biosynthetic pathway [ 15 ]. We used a Pearson’s correlation matrix test to evaluate the relationship (positive and negative) between expression of MIXTA and other genes involved in cannabinoid synthesis with expression of cannabinoids across the full seven weeks of flower development ( Figure 1 C).…”

“…Our previous study demonstrated that expression of cannabinoid biosynthetic genes peaked in weeks 4 or 5 [ 15 ]; CsMIXTA expression showed a similar pattern. It has been shown that trichomes produce most cannabinoids during the latter capitate-stalked glandular phase.…”

“…There is a strong positive correlation between CsMIXTA expression and the expression of both GPPS and OAC , enzymes which synthesize the necessary precursors (GPP and olivetolic acid, respectively) [ 15 ] for both cannabinoids and, in the case of GPPS, monoterpenes. Sessile (non-stalked) glandular trichomes produce minimal monoterpenes or cannabinoids before maturation, possessing a sesquiterpene-dominant chemotype.…”

Analysis of hormonal regulation of promoter activities ofCannabis sativaprenyltransferase 1 and 4 and salicylic acid mediated regulation of cannabinoid biosynthesis

“…Liu et al, 2021). In recent work from this lab, this point was clearly established and further, the production of CBGA was identified as rate-limiting end point cannabinoid synthesis (Apicella et al 2022).…”

Exploiting Beneficial Pseudomonas spp. for Cannabis Production

“…Hypothetically, beneficial microorganisms may be recognized as a potential threat by the plant which synthetizes phytochemicals as a defense response (Thakur et al, 2019;Balestrini et al, 2021). Supporting this, treatments with stress-related phytohormones significantly increase THC and CBD contents (Mansouri et al, 2009;Jalali et al, 2019;Apicella et al, 2021). Alternatively, promoting root growth and improving nutrient availability and uptake may allow for greater plant biomass and overall wealth, resulting in thriving secondary metabolism functions (Çakmakçı et al, 2020) and early maturation (Conant et al, 2017;Backer et al, 2019).…”