## 3 Discussion
### Phytohormone Regulation of Cannabinoid Biosynthesis  
The _in vitro_ phytohormone treatments at large did not cause concerted changes in cannabinoid pathway biosynthetic proteins (Figure 7) and cannabinoid content (Figure 6) within a period of 24 h. This juxtaposes several _in planta_ studies where phytohormones were tested by spraying on plants and changes in floral cannabinoid flower and/or gene expression were assessed. In these studies, GA [41] was found to decrease total tetrahydro-cannabinol (THC) content after 24 h, while ABA [40] caused total THC content to increase 24 h after 3 days of treatment. JA [28; 38; 57] caused total THC content to increase after several weeks of treatment. ETH [43] caused cannabidiol to increase 24 h after 6 days of treatment. SA caused THCA [57] content to decrease 1 week after 8 weeks of treatment. [PERSON] et al. [57] also tested if JA or SA changed the gene expression of either _OAC_, _CBDAS_, or _THCAS_ and found neither treatment had effects on these enzymes. In contrast, [PERSON] et al. [39] reported that SA positively regulated the expression of _TKS_, _OAC_, _CsPT1_, _CBDAS_, and _GPPS.ssu_ as early as three hours after treatment. The differences in gene expression results could be due to the different cultivars and/or treatment methods used. For example, [PERSON] et al. [57] applied weekly foliar sprays throughout floral development, while [PERSON] et al. [39] used a onetime foliar application. These _in planta_ studies were unable to explain the actual mechanisms that resulted in changed cannabinoid content in the GT since they were limited to examining at the floral tissue level. The lack of change in cannabinoid content and proteins in our _in vitro_ experiment compared to the changes in the whole plant experiments point to phytohormones exerting control on cannabinoid biosynthesis indirectly _in planta_. In fact, [PERSON] et al. [57] found that cannabinoid content correlated with plant growth and not with expression of the biosynthetic genes. Likely avenues of phytohormonal control over cannabinoid biosynthesis include manipulating primary metabolism and resource allocation in the short term or affecting trichome density in the long term. This may explain the differences in cannabinoid composition seen between different cannabis chemovars [20] or when cannabis responds to environmental stresses [34]. GT Changes in Common Between Kinetin, Jasmonic Acid, and Salicylic Acid Indicate Roles in Coordinating Trichome Specific Features  
Group 2, comprised of KIN, SA, and JA (Figure 2B), caused much larger proteome changes (greater than 10% each) than those observed for group 1 hormones. These phytohormones induced responses in the GT disc cells that were biologically similar to each other (Figure 4), as evidenced by a large number of increasing and decreasing DAPs in common (Figure 5). Significant interplay between these three hormones occurs in plants. JA and SA are largely antagonistic to each other to reduce redundancy [58], while cytokinins act synergistically with SA to activate pathogen defences [59], as well with JA to confer resistance to feeding insects [60]. Interestingly, we found that KIN, JA, and SA caused OAC to decrease in abundance in a similar fashion by an average fold-change of 0.26 times (Figure 7), which may point to a common regulatory mechanism of OAC shared by the three. This stands in contrast to [PERSON] et al. [39] who had found that SA increased _OAC_ expression. The SWATH-MS analysis we employed was not sensitive enough to detect and quantify relatively low abundant regulatory proteins which include those of the MBW complex and receptors of various phytohormone signalling pathways. However, we were able to quantify homologs of the ABA receptor PYR1 [61] and BEN1, a regulator in BA signalling [62].