## 1 Introduction
Most of these studies have focused on trichome initiation and morphogenesis, leaving open the question as to what roles phytohormones have in regulating mature trichomes, specifically in relation to their productivity. For cannabis, the question of productivity is an important one since GTs are the site for cannabinoid production, which in elite drug-type cultivars can account up to at least 20% of dry flower weight [31]. GTs in general have restructured metabolism to support high productivity; for example, tomato type VI GTs have modified central carbohydrate metabolism to feed precursors directly into secondary metabolism [32], and this is similar in cannabis [10]. Recently, productivity in cannabis GTs has been shown to be dynamic as specific cannabinoids increased with daytime progression [33], with glycolysis being an important control point. In fact, cannabinoid production can be influenced by changes in environmental growing conditions such as drought stress [34], nutrient availability [35], and photoperiod [36]. However, the main mechanisms that control GT productivity via primary metabolism [37] and the role of phytohormones are largely unknown. Several studies have examined phytohormone regulation in cannabis, typically looking at the effects of exogenously applied compounds on floral cannabinoid content. These _in planta_ experiments have found several phytohormones to be effective at changing cannabinoid production. Methyl jasmonate [28; 38], salicylic acid [39], and abscisic acid [40] were found to increase cannabinoid content. Gibberell acid decreased cannabinoids [41], while auxin analogue 1-naphthalenaecetic acid cytokinin analogue 6-benzylaminopurine [42] and ethylene donor ethephon [43] did not cause any changes. These previous studies did not discriminate between phytohormonal effects on floral tissues and trichomes. While they found cannabinoid phenotypes, the location of phytohormonal action could not be investigated in detail using _in planta_ spraying. In fact, no study to date has looked at phytohormonal regulation of trichomes in isolation. Furthermore, it remains unknown if these phytohormones reach the GT disc cells and whether they would have a direct effect on GT regulation. The effects on productivity may be indirect as a result of manipulating whole plant regulatory mechanisms. GTs are inherently challenging to study in isolation due to their microscopic size and complexity to purify in sufficient quantities. The biggest bottleneck to studying these cells is that without the ability to isolate them, it is difficult to understand the direct impact of regulatory signals on GT function. Biochemical experiments using isolated GTs have been reported for peppermint (_Mentha x piperita_ L.) [44; 45]. Utilising a similar system for cannabis, we studied the effects of different classes of phytohormones _in vitro_ on live GT disc cells, using quantitative proteomics and targeted metabolite analysis. We asked which phytohormones exert influence on trichome biological processes at a disc cell level in the following terms: magnitude of change in the disc cell proteome, if affected proteins have roles in trichome functioning/development, and if the cannabinoid biosynthetic pathway and cannabinoid content are affected. Since GTs are primarily defensive structures [6], we hypothesised that phytohormones involved in environmental stress response (specifically jasmonic acid, salicylic acid, and abscisic acid) will play important roles in regulating GTs and therefore may upregulate the cannabinoid biosynthetic pathway.