## Appendix A  
Our study showed the construction of three episomes in the p_P_fGE30 backbone containing _C. sativa_ genes for the production of OA (Appendix A, Figure A1 and Tables A1-A3). Each episome was inserted into _P. tricornutum_ via bacterial conjugation and the corresponding enzymes were successfully accumulated (Appendix A, Figure A2 and Table A4). Figure 11: _P. tricornutum_ plasmid fragments for yeast assembly and the colony PCR of recombinant _P. tricornutum_ after bacterial conjugation. (**A**) Agarose gel electrophoresis of the amplified fragments (the backbone moieties (P1 and P2), promoter (P), gene (G), terminator (T), and selection marker _ShBle_ encoding for zeocin resistance) for the plasmid constructs _Pt_OA1 and _Pt_OA2. (**B**) Agarose gel (2%) electrophoresis of the colonies. PCR was performed on the _P. tricornutum_ colonies for each construct, with the cPCR primers from Appendix A, Table A4. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Sequence Name** & **Amino Acid Sequence** & \multicolumn{1}{c}{**Length (a.a)**} & \multicolumn{1}{c}{**Accession Number (CDS)**} & \multicolumn{1}{c}{**Accession Number AA Seq**} \\ \hline  & MMRLRAGPASPALACATATAPENLLODFPDYARYPRYTRISERMIQUEKERRACKDK & & & & \\  & SMRRCNFLNETHLSQNPRYTHENQMLDARQMLVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV  
\begin{tabular}{l l l l} \multicolumn{1}{c}{**Primer Name**} & \multicolumn{1}{c}{**Sequence (y to y)**} & \multicolumn{1}{c}{**Amplion Size (bp)**} & \multicolumn{1}{c}{**Description of Product**} \\ \hline bk1-FP & CAGCGTAATATGACTCTCCCTCACATACCCCTCCTCGGCTATATATACCGACTTTTTTT & 6158 & pPTGCE0 backbone part 1 \\ bk1-FP & TITCCAACACACACATGTCCACACGCGCGCGTCAAAAAAATCTCCACACCCCTCGG & 6158 & pPTGCE0 backbone part 1 \\ bk1-FP & GGG  
Figure A4: _Cont._  
Figure 4: The cannabinoid-like metabolites detected via HPLC-UV and LC-MS analyses. (**A**) The list and (**B**) chemical structure of the targeted metabolites. A representative LC chromatogram of (**C**) 10 \(\mu\)L of metabolite extraction from _P. tricornutum Pt_OA1C1 and of (**D**) 10 mg/kg of a mixture of known cannabinoid commercial standards, both showing peaks corresponding to the retention times (RT) of cannabinoid standards. LC-MS in ESI+ analyses. Total ion chromatograph (TIC) of selected peaks from the corresponding cannabinoids, such as _P. tricornutum Pt_OA1C1 (**E**) peak at RT 19.66 min, with an \(m/z\) similar to the CBGA standard (RT 19.65 min). (**F**) The peak at RT 15.96 min, with an \(m/z\) similar to the CBDA standard (RT 15.91 min). (**G**) The peak at RT 19.66 min, with an \(m/z\) similar to the THCA standard (RT 65.04 min). Figure 5: Details of the events used in LC-MS to confirm the identity of the cannabinoids. Appendix B The In Silico Analyses Identified Putative Endogenous P. tricornutum Candidates for CB-like Biosynthesis  
To investigate the hypothesis that the endogenous enzyme could yield cannabinoids, characterization of the enzyme candidates was performed using bioinformatic tools. Putative candidate sequences for endogenous _P. tricornutum_ enzymes that were able to convert OA and GPP into CBGA were obtained from the HMMER web server [64], using the CsAPT4 amino acid sequence as a query against the Protist database. We obtained five hits where the protein B7G488 (gene ID Phatr3_J37858) (57% similarity) and the protein B7 FT51 (gene ID: Phatr3_J2738.t1) (51% similarity) had been annotated as the predicted protein members of the UbiA preyltransferase family, to which CsAPT4 belongs [49]. The phylogenetic analysis indicated that these two proteins are clustered closer, according to sequence similarity, to the _C. sativa_ APTs group (Appendix A, Figure A5). The soluble aromatic prenyltransferase from _Streptomyces_ sp., NphB, had already been characterized by [PERSON] et al. in 2005 [65], in a cluster with that from _Apergillus terreus_, a fungal APT. No hits were found by using the same approach to identify endogenous diatom-soluble APT candidates, using _Streptomyces_ sp. NphB as a query. Endogenous _P.