## 2 Biochemistry and Genetic Regulation of Aroma and Flavor Compounds in _C. sativa_ L.
### Trait Associations and Exclusivity  
The sensory and chemical diversity of _C. sativa_ L. is shaped by the interplay of genetic, metabolic, and environmental factors. Certain traits, such as terpene and cannabinoid profiles, often occur together due to shared biosynthetic pathways or genetic linkages, while others exhibit exclusivity due to metabolic competition or genetic trade-offs [46]. Understanding these relationships is crucial for optimizing breeding strategies, enhancing desired traits, and achieving consistent product profiles. Some compounds influencing the aroma and flavor perception are strongly correlated due to common biosynthetic origins. The sensory and chemical diversity of _C. sativa_ L. is \begin{table}
\begin{tabular}{c c c c} \hline
**Terpene** & **Class** & **Aroma Description 1** & **Flavor Impression 1** \\ \hline \(\alpha\)-Terpinene & Monoterpene & Herbal, citrus & Mild, spicy \\ \(\gamma\)-Terpinene & Monoterpene & Citrus, lemon-like & Clean, tangy \\ \(\alpha\)-Phellandrene & Monoterpene & Peppery, citrus & Pungent, slightly bitter \\ Sabinene & Monoterpene & Spicy, peppery & Warm, bitter \\
1,8-Cineole & Monoterpene & Eucalyptus, minty & Cooling, spicy \\ Camphene & Monoterpene & Earthy, woody & Pungent \\ \(\delta\)-3-Carere & Monoterpene & Sweet, cedar-like & Earthy \\ \(\beta\)-Caryophyllene & Sesquiterpene & Spicy, woody, peppery & Warm, peppery \\ \(\alpha\)-Humulene & Sesquiterpene & Earthy, woody & Bitter, hoppy \\ Farnesene & Sesquiterpene & Green apple, woody & Mild, sweet \\ Nerolidol & Sesquiterpene & Woody, citrusy & Subtle, bitter \\ Bisabolol & Sesquiterpene & Floral, sweet & Mildly bitter, soft \\ \hline \end{tabular}  
* Classification and descriptors are synthesized from multiple sources, including [PERSON] et al. (2019) [47], [PERSON] et al. (2020) [5], [PERSON] and [PERSON] (2008) [48], and others cited throughout Section 2.1.  
\end{table} 
Table 1: _Cont._influenced by a complex interplay of genetic, metabolic, and environmental factors. Certain traits, such as terpene and cannabinoid profiles, often co-occur due to shared biosynthetic pathways or genetic linkages, while others may exhibit exclusivity resulting from metabolic competition or genetic trade-offs [46]. For example, terpen and cannabinoids both originate from the isoprenoid pathway, and their production relies on shared precursors such as GPP. This overlap often leads to the co-occurrence of specific terpene and cannabinoid profiles [6; 10]. These combinations likely arise from selective pressure during breeding programs that target complementary traits to meet consumer preferences or therapeutic needs. Understanding these relationships is crucial for optimizing breeding strategies, enhancing desired traits, and achieving consistent product profiles [10]. Empirical studies have demonstrated correlations between specific terpene and cannabinoid profiles, suggesting coordinated regulation. For instance, integrative analyses of glandular trichomes from various cannabis strains revealed co-expression networks of genes involved in both cannabinoid and terpene biosynthesis [46]. This co-expression indicates a coordinated regulation of these pathways, likely due to shared precursors and biosynthetic routes as noted above. Additionally, variations in terpene profiles among cannabis cultivars have been linked to differences in the cannabis TPS gene family. A study characterizing five cannabis cultivars with contrasting terpene profiles identified 33 different cannabis TPS genes [6]. The variations in the cannabis TPS gene family composition and expression levels contribute to the diverse terpene profiles observed across the cannabis cultivars. While these studies highlight the coordinated regulation of cannabinoid and terpene biosynthesis, direct evidence of metabolic competition between these pathways remains limited.