# Multi-Omics Approaches to Study Molecular Mechanisms in _Camanabis sativa_
## 5 Conclusions  
The development of NGS technologies and recent advances in biotechnology has made it possible to greatly improve our understanding of the genetics and metabolomics that underpin trait differences in cannabis cultivars. Table 2 shows which omics technology was applied to study cannabis, and highlights how many omics studies are focused on metabolomics, which appears to be the most prevalent approach. The table also reiterates that very few QTL investigations on cannabis have been completed to date. However, there is a clear increase in transcriptomic studies based on RNA-Seq in recent years, which is a result of the availability of new and better cannabis reference genomes and lower costs associated with creating these datasets [25; 65]. NGS has also facilitated a greater uptake of multi-omics approaches, showed in Table 3. The results of the investigations based on these technologies have elucidated more about the complex cannabis metabolomic matrix, and some genes involved in cannabinoid biosynthesis have been identified. A relevant example is the improvement in the characterization of the complex CsTPS gene family, and a better definition of the role of some key genes belonging to this family [43; 72; 85]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Omic Technologies** & **Description** & **Reference** \\ \hline Metabolomics/GC-Cannabinoid synthase genotyping, linkage mapping and QTL analysis & Study about cannabinoids and terpenoids biosynthesis in cannabis & [38; 62] \\ \hline Metabolomics/Analytical methods available for cannabinoids analysis & Review—Cannabis metabolites & [32] \\ \hline Metabolomics/GC-FID method & Definition of cannabis chemovars based on their terpenoid profile. The Effect of Light Spectrum on the cannabis morphology. & [46; 50] \\ \hline Metabolomics/Supercritical CO\({}_{2}\) extraction of the cannabis infloresence & Study of cannabinoids and terpenoids biosynthesis in cannabis & [40] \\ \hline Metabolomics/GC-MS/LC-MS & Overview about methods for the chemical characterization of cannabis & [44] \\ \hline Metabolomics/HRMS—LC-HRMS & Potential in the definition of cannabis chemovars of HRMS techniques & [60; 61] \\ \hline Metabolomics/SFE/SPE & Isolation of tetrahydrorocannabinol from cannabis & [52] \\ \hline Metabolomics/SPME/DLLME/LC-QQQ-MS & Physicochemical characterization of cannabis & [53] \\ \hline Metabolomics/Analytical methods available for cannabinoids and terpenoids analysis & Review—Cannabinomics: Metabolomics applications in Cannabis. Terpenoids properties. & [20; 42] \\ \hline Metabolomics/Structural classification of phytocannabinoids & Study about phytocannabinoids & [39] \\ \hline Metabolomics/GC-EIMS & Investigation about lipids extracted from cannabis seeds & [47] \\ \hline Metabolomics/HPLC & Investigation about the major cannabinoids: CBD, CBG and THC. & [48; 49] \\ \hline Genomics/Illumina sequencing approach & The genome of cannabis. To assess the completeness and representivity of the ’PK’, ’FN’, and ’CBDRx’ assemblies, Illumina sequences and 55 public whole-genome-sequenced samples were used & [5] \\ \hline Genomics/Reference assemblies were annotated with mRNA sequencing (Iso-Seq) approach & Sequence and annotation of 42 cannabis genomes & [25] \\ \hline Genomics/Dratt genome sequence using PacBio single-molecule sequencing & A reference genome of wild cannabis & [27] \\ \hline Genomics/PCR genotyping/SNP markers & Phylogenetic relationship, population genetics, and correlation with cannabis metabolites & [8] \\ \hline Genomics/GWAS & Investigation of novel cannabis genetic variants responsible for cannabis complex traits & [68; 69] \\ \hline Genomics/whole-genome resequencing approach & A whole-genome resequencing of of 110 worldwide accessions & [64] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Significant omics studies examined in this review.