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RESEARCH ARTICLE
Terpene synthases from Cannabis sativa
Judith K. Booth
1
, Jonathan E. Page
2,3
, Jo
¨rg Bohlmann
1,3
*
1Michael Smith Laboratories, University of British Columbia, East Mall, Vancouver, B.C., Canada, V6T 1Z4,
2Anandia Laboratories, Lower Mall, Vancouver, B.C., Canada, V6T 1Z4, 3Botany Department, University of
British Columbia, University Blvd, Vancouver, B.C., V6T 1Z4
*bohlmann@msl.ubc.ca
Abstract
Cannabis (Cannabis sativa) plants produce and accumulate a terpene-rich resin in glandular
trichomes, which are abundant on the surface of the female inflorescence. Bouquets of dif-
ferent monoterpenes and sesquiterpenes are important components of cannabis resin as
they define some of the unique organoleptic properties and may also influence medicinal
qualities of different cannabis strains and varieties. Transcriptome analysis of trichomes of
the cannabis hemp variety ‘Finola’ revealed sequences of all stages of terpene biosynthesis.
Nine cannabis terpene synthases (CsTPS) were identified in subfamilies TPS-a and TPS-b.
Functional characterization identified mono- and sesqui-TPS, whose products collectively
comprise most of the terpenes of ‘Finola’ resin, including major compounds such as β-myr-
cene, (E)-β-ocimene, (-)-limonene, (+)-α-pinene, β-caryophyllene, and α-humulene. Tran-
scripts associated with terpene biosynthesis are highly expressed in trichomes compared to
non-resin producing tissues. Knowledge of the CsTPS gene family may offer opportunities
for selection and improvement of terpene profiles of interest in different cannabis strains and
varieties.
Introduction
Cannabis sativa, referred to here as cannabis, has been used for millennia as a medicine and
recreational intoxicant [1,2]. The species Cannabis sativa comprises both marijuana and
hemp [3,4,5]. Medicinal cannabis is highly valued for its pharmacologically active cannabi-
noids, a class of terpenophenolic metabolites unique to cannabis. These compounds are
primarily found in the resin produced in the glandular trichomes of pistillate (female) inflores-
cences. Cannabis resin also contains a variety of monoterpenes and sesquiterpenes (Fig 1),
which are responsible for much of the scent of cannabis flowers and contribute characteristi-
cally to the unique flavor qualities of cannabis products. Similarly, terpenes in hop (Humulus
lupulus), a close relative of cannabis, are an important flavoring component in the brewing
industry. Differences between the pharmaceutical properties of different cannabis strains have
been attributed to interactions (or an ‘entourage effect’) between cannabinoids and terpenes
[6,7]. For example, the sesquiterpene β-caryophyllene interacts with mammalian cannabinoid
receptors [8]. As a result, medicinal compositions have been proposed to incorporate blends of
cannabinoids and terpenes [9]. Terpenes may contribute anxiolytic, antibacterial, anti-inflam-
matory, and sedative effects [6].
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 1 / 20
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OPEN ACCESS
Citation: Booth JK, Page JE, Bohlmann J (2017)
Terpene synthases from Cannabis sativa. PLoS
ONE 12(3): e0173911. https://doi.org/10.1371/
journal.pone.0173911
Editor: Bjo¨rn Hamberger, Michigan State
University, UNITED STATES
Received: January 9, 2017
Accepted: February 28, 2017
Published: March 29, 2017
Copyright: ©2017 Booth et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: GenBank accession
numbers are within the paper, under the "GenBank
Accessions" section.
Funding: This work was supported with funds to
JB from a Discovery Grant of the Natural Sciences
and Engineering Research Council (NSERC) of
Canada and an NSERC Graduate Scholarship to
JKB. JEP contributed to the study in his academic
capacity as an Adjunct Professor in the Department
of Botany at the University of British Columbia. JEP
is also the CEO and President of Anandia Labs Inc.,
which is hereby acknowledged. The funder
(NSERC) provided financial support in the form of
Terpene biosynthesis in plants involves two pathways to produce the general 5-carbon iso-
prenoid diphosphate precursors of all terpenes, the plastidial methylerythritol phosphate
(MEP) pathway and the cytosolic mevalonate (MEV) pathway. These pathways ultimately con-
trol the different substrate pools available for terpene synthases (TPS). The MEP pathway is
comprised of seven steps that convert pyruvate and glyceraldehyde-3-phosphate into isopente-
nyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) (Fig 2A). Enzymes thought
to be critical for flux regulation through this pathway include the first two and final two
steps: 1-deoxy-D-xylulose 5-phosphate synthase, 1-deoxy-D-xylulose 5-phosphate reductase,
4-hydroxy-3-methylbut-2-enyl diphosphate synthase, and 4-hydroxy-3-methylbut-2-enyl
diphosphate reductase [10,11]. The MEV pathway converts three units of acetyl-CoA to IPP,
which is then isomerized to DMAPP by IPP isomerase. A rate-limiting step in this six-step
pathway is 3-hydroxy-3-methylglutaryl-CoA reductase, which produces mevalonate [12]. IPP
and DMAPP are condensed into longer-chain isoprenoid diphosphates by prenyltransferases,
which include geranyl diphosphate (GPP) synthase (GPPS) and farnesyl diphosphate (FPP)
synthase (FPPS). GPPS and FPPS condense one unit of IPP and one or two units of DMAPP
to form 10- and 15-carbon linear trans-isoprenoid diphosphates, respectively. GPP is the
10-carbon precursor of monoterpenes and is typically derived from 5-carbon isoprenoid
diphosphate units of the MEP pathway. GPP is also a building block in the biosynthesis of
Fig 1. Glandular trichomes on the surface of pistillate inflorescences and leavesof Cannabis sativa
‘Finola’. The inflorescence (left) with a high density of glandular trichomes was at five weeks post onset
of flowering. Non-inflorescence leaves (right) have lower density of glandular trichomes. Structures of
representative cannabis resin components are shown in white: monoterpenes(top row), sesquiterpenes
(middle row), and cannabinoids (bottom row). GBGA = cannabigerolic acid; THCA = tetrahydrocannabinolic
acid; CBDA = cannabidiolic acid.
https://doi.org/10.1371/journal.pone.0173911.g001
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 2 / 20
salary through a fellowship for JKB and research
materials. Anandia Labs provided in-kind support
in the form of plant materials. Anandia Labs did not
provide financial support for this project. The
funder (NSERC) and Anandia Labs did not play a
role in the study design, data collection and
analysis, decision to publish, or preparation of the
manuscript. The specific roles of all authors are
articulated in the ‘author contributions’ section.
Competing interests: JEP is the CEO and President
of Anandia Labs Inc. JB is a consultant and adviser
to CannaRoyalty Corp. (since December 2016).
These affiliations do not alter our adherence to
PLOS ONE policies on sharing data and materials.
cannabinoids [13,14]. FPP is the 15-carbon precursor of sesquiterpenes and is commonly
produced from 5-carbon isoprenoid diphosphate units of the cytosolic mevalonate (MEV)
pathway. GPPSs exist as homo- or heterodimeric enzymes. In hops, the closest known relative
of cannabis, heterodimeric GPPSs can produce both GPP and the 20-carbon geranylgeranyl
diphosphate (GGPP), with the ratio of large to small G(G)PPS subunits controlling the product
outcome [15,16,17]. The linear isoprenoid diphosphates GPP and FPP are substrates for
monoterpene synthases (mono-TPS) and sesquiterpene synthases (sesqui-TPS), respectively,
which diversify these precursors into a large number of different mono- and sesquiterpenes.
TPS are typically encoded in large and diverse gene families in plants [18], where they con-
tribute to both general and specialized metabolism. The plant TPS gene family has been anno-
tated with six subfamilies. In angiosperms, the subfamily TPS-b is typically comprised of
mono-TPS and TPS-a enzymes are often sesquiterpene synthases. TPS produce cyclic and acy-
clic terpenes via carbocationic intermediates, formed by divalent metal co-factor dependent
elimination of the diphosphate. The reactive cationic intermediate can undergo cyclization
and rearrangements until the reaction is quenched by deprotonation or water capture [19].
Many TPS form multiple products from the same substrate.
The terpene composition of cannabis resin varies substantially based on genetic, environ-
mental, and developmental factors [20,21,22,23]. Concentrations and ratios of cannabinoids
are relatively predictable for different strains, but terpene profiles are often unknown or unpre-
dictable [20,23]. To select and improve cannabis strains with desirable terpene profiles, it is
necessary to identify genes responsible for terpene biosynthesis, which can be accomplished by
harnessing available cannabis transcriptome and genome resources. Draft genomes and tran-
scriptomes for the marijuana strain Purple Kush and the hemp variety ‘Finola’ have previously
Fig 2. Schematic of the plastidial methylerythritol phosphate pathway (MEP) and mevalonic acid
pathway (MEV) and transcript abundance in different parts of cannabis. Steps shown in bold (a) were
included in the qPCR analysis (b) of relative abundance of transcripts. Letters indicate significantly different
means between tissues (tested within each gene), Fisher’s LSD (alpha = 0.05). Abbreviations: Tr = trichome;
Le = leaf; Sf = stamenate flower; Ro = root; Sm = stem.
https://doi.org/10.1371/journal.pone.0173911.g002
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 3 / 20
been published [24]. We used these resources to explore the expression of genes involved in all
stages of terpene biosynthesis. We identified nine TPS gene models in the ‘Finola’ transcrip-
tome. TPS genes and gene transcripts in the MEP and MEV pathways were highly expressed
in floral trichomes. We identified biochemical functions of TPS that are highly expressed in
‘Finola’. The TPS enzymes characterized account for most of the terpenes found in ‘Finola’
resin.
Materials and methods
Plant materials
Cannabis seeds, ‘Finola’, were obtained from Alberta Innovates Technology Futures (www.
albertatechfutures.ca). All plants were grown indoors in a growth chamber under a Health
Canada license. Seeds were germinated on filter paper, then transferred to 4:1 Sunshine Mix
#4 (www.Sungro.com):perlite. Daylight length was 16 h under fluorescent lights, and ambient
temperature 28˚C. About two weeks after germination, seedlings were transferred to larger
pots. After repotting, all plants were fertilized weekly with Miracle-Gro all-purpose plant food
(24-8-26) (www.miraclegro.com) according to manufacturer’s instructions.
Terpene extraction
Pistillate inflorescences were collected and trimmed of leaves and stems. All flowers from
an individual plant were pooled. Tissue samples of ~0.2 g were weighed to determine fresh
weight. Three rounds of extraction in 1 ml of pentane were performed for 1 hour each at room
temperature with gentle shaking. Isobutyl benzene was added as an internal standard. After
three extractions, no terpenes were identified in a fourth solvent extraction. Floral tissue was
then dried overnight and weighed to determine dry weight. All three pentane extracts were
combined for a total volume of 3 ml for analysis.
Trichome isolation
The heads of glandular trichomes were isolated from whole inflorescences as previously
described [25] without XAD-4 and with the addition of 5 mM aurintricarboxilic acid in the
isolation buffer. Instead of a cell disruptor, floral tissue was vortexed with glass beads in a Fal-
con tube to remove trichome heads. After vortexing, trichomes were separated from beads and
green tissue by filtration through a 105 μm nylon mesh. Trichomes were concentrated by gen-
tle centrifugation in ice-cold buffer. The supernatant was removed with a pipette, and the pel-
let of trichomes was immediately frozen in liquid nitrogen.
Metabolite analysis
Gas chromatography (GC) analysis of floral extracts was performed on an Agilent (www.
chem.agilent.com) 7890A GC with a 7683B series autosampler and 7000A TripleQuad mass
spectrometer (MS) detector at 70 eV electrospray ionization with a flow rate of 1 ml min
-1
He.
The column was an Agilent VF-5MS or DB-5MS (30 m, 250 μm internal diameter, 0.25 μm
film). The following temperature program was used: 50˚C, then increase 150˚C min
-1
to
320˚C, hold for 5 minutes. Injection was pulsed splitless at 250˚C. Compounds were identified
by comparison of retention index and mass spectra to authentic standards. Standards were
available for all monoterpenes and the following sesquiterpenes: β-caryophyllene, α-humulene,
farnesol, valencene, germacrene D, and alloaromadendrene. Tentative identifications for
all other sesquiterpenes were made by comparison of retention index and mass spectra
to National Institute of Standards and Technology (NIST) MS library. Identifications of
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 4 / 20
bergamotene, δ-selinene, and farnesene were strengthened by comparison to essential oils of
Citrus bergamia (Bergamot) and Pimenta racemose (Bay) (www.lgbotanicals.com). TPS assay
products were analyzed by the same procedure described above for plant extracts, but with the
following temperature program: 50˚C for 3 minutes, then increase 15˚C min
-1
to 280˚C, hold
for 2 minutes. Assay products were analyzed using Agilent HP-5 and DB-Wax columns (30 m
length, 250 μm internal diameter, 0.25 μm film). For cold injection of sesqui-TPS assay prod-
ucts, the following program was used on a DB-Wax column: 40˚C for 3 minutes, then increase
10˚C min
-1
to 230˚C, hold for 7 minutes. Injection was at 40˚C with a 1:1 split ratio. Chiral
analysis of terpenes was done using a Cyclodex-B column (30 m length, 250 μm internal diam-
eter, 0.25 μm film). Injection was pulsed splitless, with the following program: 40˚C for 1 min-
ute, then increase 5˚C min
-1
to 100˚C, then increase 15˚C min
-1
to 250˚C, hold for 4 minutes.
Chirality was determined by retention index and comparison with authentic standards.
cDNA cloning and characterization of TPS genes
Total RNA was isolated from ‘Finola’ flowers, leaves, stem, and roots using Invitrogen PureLink
Plant RNA reagent (www.thermofisher.com). RNA quality and concentration was measured
with a Bioanalyzer 2100 RNA Nanochip assay (www.agilent.ca). cDNA was synthesized with the
Superscript III reverse transcriptase kit (Thermo Fisher). Full length and N-terminally truncated
cDNAs without transit peptides where applicable [26] were amplified from cDNA using gene-
specific primers (S1 Table) designed from published transcriptomic data [24]. N-terminal transit
peptides were predicted based on sequence alignments [27] and using the TargetP and ChloroP
servers [28]. PCR amplified ‘Finola’ cDNAs were ligated into pJET vector (www.clontech.com)
for sequence verification, and subcloned into expression vectors pET28b+ (www.endmillipore.
ca) or pASK-IBA37 (www.iba-lifesciences.org) in the case of CsTPS5FN.
High-confidence full-length TPS cDNA candidates from Purple Kush (CsTPS13PK,
CsTPS30PK, and CsTPS33PK) were synthesized by GenScript (www.genscript.com) into
pET28b+. For this purpose, putative TPS sequences from Purple Kush transcriptome data
were verified by comparison to genomic sequences [24].
Plasmids were transformed into E.coli strain BL21DE3-C43 for heterologous protein
expression, as previously described [29]. Recombinant protein was purified using the GE
healthcare His SpinTrap kit (www.gelifesciences.com) according to manufacturer’s instruc-
tions. Binding buffer for purification was 20 mM 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethane-
sulfonic acid (HEPES) (pH 7.5), 500 mM NaCl, 25 mM imidazole, and 5% glycerol. Cells were
lysed in binding buffer supplemented with Roche complete protease inhibitor tablets (life-
science.roche.com) and 0.1 mg ml
-1
lysozyme. Elution buffer was 20 mM HEPES (pH 7.5), 500
mM NaCl, 350 mM imidazole, and 5% glycerol. Purified protein was desalted through Sepha-
dex into TPS assay buffer. In vitro assays were performed in 500 μl volume by incubating puri-
fied protein with isoprenoid diphosphate substrates (Sigma) as previously described [30],
except that the TPS assay buffer was 25 mM HEPES (pH 7.3), 100 mM KCl, 10 mM MgCl
2
, 5%
glycerol, and 5 mM DTT. Isoprenoid diphosphate substrates were dissolved in 50% methanol
and added to the assay at final concentrations of 32 μM (GPP) and 26 μM (FPP). Enzyme con-
centrations were variable ranging from 20 to 100 μg per 500 μl assay volume. Assays were over-
laid with 400 μl hexane or pentane, with 2.5 μM isobutyl benzene as internal standard.
Nicotiana benthamiana transformation and transient expression
The CsTPS5FN coding sequence was inserted into the Golden Gate plant expression vector
pEAQ-GG, which contains a CaMV 35S promoter. This construct and the suppressor-of-
silencing gene p19 were transformed into Agrobacterium tumefasciens strain AGL1. For
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 5 / 20
infiltration, A.tumefasciens was grown overnight as previously described [31], then pelleted
and resuspended in 10 mM 2-(N-morpholine)-ethanesulphonic acid (MES) buffer, pH 5.8, 10
mM MgCl
2
, 20 μM acetosyringone to OD
600
0.5. Equal volumes of bacteria, 25 ml each, con-
taining TPS5 and p19 were infiltrated into the abaxial side of 4-week-old N.benthamiana
plants. Infiltrated plants were grown for three days in the dark. Infiltrated leaves were har-
vested and ground in TPS assay buffer, and enzyme activity assays were conducted as above.
RT-qPCR analysis of transcript abundance
cDNA for qPCR was synthesized using the Maxima First Strand cDNA synthesis kit (Thermo
Fisher) according to manufacturer’s instructions. qPCR reactions were done in 15 μl volumes
with SsoFast EvaGreen supermix (Bio-Rad), 4 μl template (2 ng), and 0.3 μM primers. Primers
(S2 Table) were designed using Primer3 software [32]. Reference genes were chosen by geN-
orm [33], analyzed with qBase+ software (www.biogazelle.com). Reference genes used for RT-
qPCR of early isoprenoid biosynthesis across different plant organs were actin and CDK3. For
RT-qPCR of TPS transcripts in trichomes, reference genes were CDK3 and GAPDH. RT-qPCR
analyses were done with four biological and two technical replicates for the early isoprenoid
biosynthetic transcripts in different organs. For TPS transcript analysis in trichomes, three bio-
logical and three technical replicates were performed. Gene expression was analyzed using
qBase+. Statistical analysis was performed by ANOVA on log-transcript abundance, with Bon-
ferroni correction.
TPS gene prediction and phylogeny
‘Finola’ genome and transcriptome assemblies [24] were downloaded from the cannabis
genome browser (http://genome.ccbr.utoronto.ca/cgi-bin/hgGateway). These assemblies were
used as the subject of a tBLASTn search using 71 TPS genes (S3 Table) downloaded from Gen-
Bank and Phytozome. Gene and splice site prediction was performed on scaffolds containing
regions with similarity to TPS sequences using the Exonerate gene prediction algorithm [34].
A preliminary Purple Kush genome assembly based on PacBio (www.pacb.com) sequencing
data was also used. Predicted genes were manually curated against earlier Purple Kush
sequence data, and examined to establish open reading frames, start codons, and stop codons.
A maximum likelihood phylogeny was built using phylogeny.fr [35]. The alignment used for
input was built using the MUSCLE algorithm with all translated amino acid sequences from
the predicted TPS gene models from cannabis and the 71 published TPS sequences listed
above. Alignments were curated using the Gblocks algorithm, and tree construction was per-
formed using PhyML 3.0 with 100 bootstrap replicates.
Results
Terpene profiles of cannabis inflorescences
We used the C.sativa oilseed hemp variety ‘Finola’ to investigate terpene profiles of pistillate
flowers. ‘Finola’ was chosen because reference draft genome and transcriptome assemblies
were published [24]. Pistillate flowers, which have the highest density of glandular trichomes
relative to other parts of the plant (Fig 1), were sampled to cover early to mid-stage inflores-
cences between three and eight weeks post onset of flowering, where onset of flowering is
defined as the first appearance of pistils. Independent of the stage of inflorescence, the most
abundant monoterpenes were myrcene, (+)-α-pinene, (-)-limonene, (+)-β-pinene, terpino-
lene, and (E)-β-ocimene (Table 1). The most abundant sesquiterpenes were β-caryophyllene,
α-humulene, bergamotene, and farnesene. Terpene profiles showed considerable variations
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 6 / 20
between individual plants as indicated with the relatively high standard deviation (Table 1).
No trends were observed for individual metabolites as a function of inflorescence develop-
ment, but total monoterpenes increased compared to sesquiterpenes as inflorescences
matured. Mid-stage flowers (~4 weeks post onset of flowering) had a mean monoterpene con-
tent of 389 μg g
1
DW (SE = 44, n = 9), and a mean sesquiterpene content of 34 μg g
1
DW
(SE = 6.3, n = 9).
Transcriptome mining of early isoprenoid biosynthesis genes
We queried the ‘Finola’ transcriptome for transcripts involved in the early stages of isoprenoid
biosynthesis. We combined four transcriptome sets downloaded from the Cannabis Genome
Browser (http://genome.ccbr.utoronto.ca/cgi-bin/hgGateway), including transcripts from
developing seeds, mature pistillate flowers, stamenate (male) flowers, and whole seedlings. The
tBLASTn algorithm was used to search translated ‘Finola’ nucleotide sequences, using amino
acid sequences from Vitis vinifera and Arabidopsis thaliana, and an e-value cut-off of 1
−10
.
At least one full-length or nearly full-length (>95%) transcript was found for each of the
core genes in the MEP and MEV pathways, and linear isoprenoid diphosphate prenyltrans-
ferases (Fig 2B). The genes included in the analysis of the MEP pathway were 1-deoxy-D-xylu-
lose 6-phosphate (DOXP) synthase (DXS), DOXP reductoisomerase (DXR), 2-C-methyl-D-
erythritol cytidyltransferase (MCT), 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase
(CMK), 4-hydroxy-3-methyl-but-2-enyl diphosphate (HMB-PP) synthase (HDS), and HMB-
PP reductase (HDR). Two versions of DXS, CsDXS1 and CsDXS2, were found, which are
62.8% identical at the amino acid level. In a phylogeny, CsDXS1 clusters with members of
the DXS subfamily DXS-I of other plant species, and CsDXS2 clusters with members of the
DXS-II subfamily (S1 Fig).
The genes included in the MEV pathway analysis were 3-hydroxy-3-methylglutaryl-CoA
(HMG-CoA) synthase (HMGS), HMG-CoA reductase (HMGR), mevalonate kinase (MK),
phospho-mevalonate kinase (PMK), mevalonate-5-phosphate decarboxylase (MPDC), and
IPP isomerase (IDI). At least one transcript was found corresponding to each enzyme. Two
transcripts were found for HMGR, HMGR1 and HMGR2, which are 72.7% identical at the
amino acid level.
As candidate prenyltransferases, we found transcripts of a heterodimeric GPPS system sim-
ilar to that characterized in hop [17], with a GPPS large subunit (GPPS.lsu) and a GPPS small
subunit (GPPS.ssu). Two transcripts were identified corresponding to FPPS, 80.3% identical to
one another at the amino acid level.
Table 1. Relative composition of terpene profiles in C.sativa ’Finola’ pistillate flowers. Twenty two individual plants were sampled. Contribution of indi-
vidual terpenes is expressed as a proportion of the total terpenes within a given class (i.e., monoterpenes or sesquiterpenes).
Metabolite Percent Proportion (mean ±st. dev) Terpene class
(+)-α-Pinene 23 ±17 Monoterpene
(+)-β-Pinene 8.6 ±4.6 Monoterpene
Myrcene 27 ±21 Monoterpene
(-)-Limonene 12 ±10 Monoterpene
(E)-β-Ocimene 10 ±6.5 Monoterpene
Terpinolene 18 ±14 Monoterpene
β-Caryophyllene 46 ±13 Sesquiterpene
Bergamotene 3.6 ±3.0 Sesquiterpene
Farnesene 4.4 ±3.6 Sesquiterpene
α-Humulene 19 ±7.6 Sesquiterpene
https://doi.org/10.1371/journal.pone.0173911.t001
Terpene synthases from Cannabis sativa
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RT-qPCR expression analysis of isoprenoid biosynthetic transcripts
To assess gene expression of isoprenoid biosynthesis across different parts of the cannabis
plant, we used qRT-PCR to examine the transcript abundance of prenyltransferases and key
genes in the MEP and MEV pathways. We selected genes for three steps in the MEP pathway,
DXS,DXR, and HDR, as well as two MEV pathway genes, HMGR and IDI. We also included
the two FPPS genes. In heterodimeric GPPS, the rate of GPP biosynthesis is governed by ratios
of small to large subunits, with higher ratios of small to large subunits leading to higher GPP
formation [17]. We therefore measured transcript levels of the GPPS.ssu gene. Transcript levels
were determined in ‘Finola’ leaves, stems, roots, staminate flowers, and glandular trichomes
from pistillate flowers. Pistillate flowers were harvested between 10–12 weeks post germination.
CsDXS1 was expressed in all samples, with no significant differences between different parts
of the plant (Fig 2B). CsDXS2 was also expressed in all samples. Levels of CsDXS1 and CsDXS2
transcripts were not significantly different except in roots, where average CsDXS2 levels were
14-fold more abundant than CsDXS1.HMGR1 and HMGR2 were both expressed in every sam-
ple. Their transcript abundances were not significantly different, except in leaves and roots
where HMGR2 was significantly more highly expressed. Abundances of FPPS transcripts in
roots and staminate flowers were significantly different between the two FPPS genes. The MEP
pathway genes DXR and HDR were significantly more highly expressed in trichomes and
leaves. Cannabis leaves bear glandular trichomes, but much less densely than flowers. Genes in
the MEP pathway were also more highly expressed in trichomes and leaves than genes of the
MEV pathway. Transcripts of GPPS.ssu were very highly abundant (>25 fold higher) in tri-
chomes compared to other tissues.
Members of the cannabis TPS gene family
In the ‘Finola’ (FN) trichome transcriptome we identified nine full-length or nearly full-length
(predicted >95% of amino acid length) and six partial putative TPS genes (CsTPS FN). A maxi-
mum likelihood phylogeny of the nine full-length CsTPSFN predicted protein sequences and rep-
resentative TPS from other plant species placed the CsTPSFN most closely with each other and
with TPS from hop (HlSTS1 and HlSTS2) indicating a recent expansion of TPS genes in the Can-
nabaceae (Fig 3). Five of the nine CsTPSFN (CsTPS1FN, CsTPS2FN, CsTPS3FN, CsTPS5FN,
CsTPS6FN) clustered with members of the TPS-b subfamily, and the remaining four (CsTPS4FN,
CsTPS7FN, CsTPS8FN, CsTPS9FN) clustered with the TPS-a subfamily. Two of the CsTPSFN
TPS-b genes, CsTPS1FN and CsTPS2FN, encode predicted proteins that were 98.7% and 96.8%
identical to CsTPS1 and CsTPS2 previously reported [36] and identified there as (-)-limonene
synthase (CsTPS1) and (+)-α-pinene synthase (CsTPS2) from the C.sativa strain ‘Skunk’.
Functional characterization of CsTPSFN TPS-b subfamily members
CsTPSFN were cloned as cDNAs from ‘Finola’ pistillate flowers or synthesized for heterologous
expression and identification of product profiles of the encoded enzymes. We cloned four TPS-
b family members, CsTPS1FN,CsTPS2FN,CsTPS5FN, and CsTPS6FN, from cDNA. CsTPS3FN
could not be cloned from cDNA and was obtained as a synthetic cDNA. Three TPS-b sequences
from the Purple Kush (PK) trichome transcriptome, CsTPS13PK,CsTPS30PK, and CsTPS33PK,
were also synthesized for comparison. These five CsTPS from ‘Finola’ and three from Purple
Kush were expressed as recombinant proteins and then tested for activity with GPP and FPP
and products identified by GC-MS analysis (Fig 4,Table 2,S2 and S3 Figs).
The major product of CsTPS1FN was (-)-limonene, with minor products of (+)-α-pinene,
camphene, (+)-β-pinene, and myrcene (Fig 4). CsTPS2FN produced mostly (+)-α-pinene,
with minor amounts of (+)-β-pinene, myrcene, (-)-limonene, β-phellandrene and a monoterpene
Terpene synthases from Cannabis sativa
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Fig 3. Maximum likelihood phylogeny of CsTPS. Within the TPS-a and TPS-b subfamilies, TPS from the Cannabaceae, including cannabis and hops, are
more closely related to one another than to TPS from other angiosperms. Cannabis TPS are in bold. The cannabis strain or variety of origin is indicated by two
letters following the TPS#: FN: ‘Finola’, SK: ‘Skunk’, PK: Purple Kush. Branches with bootstrap values >80% (100 repetitions) are indicated with a grey dot.
TPS of other species included are from Pp: Physcomitrella patens, Os: Oryza sativa, Cm: Cucurbita maxima, At: Arabidopsis thaliana, Cb: Clarkia breweri,
Ag: Abies grandis, Pa: Picea abies, Fa: Fragaria ananassa, Am: Antirrhinum majus, Mp: Mentha x piperita, Rc: Ricinus communis, Ci: Cichorium intybus, Sl:
Solanum lycopersicum, Nt: Nicotiana tabacum, Le: Lycopersicum esculentum, Ga: Gossypium arboreum, St: Solanum tuberosum, Vv: Vitis vinifera, Hl:
Humulus lupulus, So: Salvia officinalis, Cl: Citrus limon, Ms: Mentha spicata, Pf: Perilla frutescens. ‘S’ suffix = synthase.
https://doi.org/10.1371/journal.pone.0173911.g003
Terpene synthases from Cannabis sativa
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tentatively identified as isoterpinolene (Fig 4). CsTPS3FN produced myrcene as a single detectable
product when incubated with GPP (Fig 4). CsTPS30PK also produced only myrcene when
tested with GPP (S2 Fig). These two single-product myrcene synthases share only 54.5% amino
acid identity. CsTPS5FN also produced myrcene as its most abundant monoterpene product
(37%) (Fig 4), but unlike CsTPS3FN and CsTPS30PK, CsTPS5FN produced four additional
Fig 4. Representative GC-MS traces showing products of CsTPSFN TPS-b subfamily members. Black
traces show GC-MS total ion chromatogram from CsTPS assays with GPP. Green trace, dotted line, is a
representative terpene profile from a ‘Finola’ inflorescence. (a) shows representative chromatograms from six
TPS and a ‘Finola’ floral extract run on an HP-5 GC column. (b) shows the representative chromatogram from
CsTPS2FN run on a DB-Wax GC column. Peaks: a) α-pinene, b) camphene, c) sabinene, d) β-pinene, e)
myrcene, f) α-terpinene, g) limonene, h) (Z)- β-ocimene, i) (E)-β-ocimene, j) γ-terpinene, k) terpinolene, l) β
-phellandrene, m) isoterpinolene. i.s. = internal standard
https://doi.org/10.1371/journal.pone.0173911.g004
Table 2. Functionally characterized CsTPS enzymes.
Functional gene ID Nearest ’PK’ TPS gene model Major products Strain of origin Activity on GPP Activity on FPP
CsTPS1FN CsTPS1PK (-)-limonene Finola +++ np
CsTPS1SK
ŧ
CsTPS1PK (-)-limonene Skunk nd nd
CsTPS2FN CsTPS2PK (+)-α-pinene Finola +++ np
CsTPS2SK
ŧ
CsTPS2PK (+)-α-pinene Skunk nd nd
CsTPS3FN CsTPS3PK β-myrcene Finola +++ np
CsTPS4FN CsTPS9PK alloaromadendrene Finola + +++
CsTPS5FN CsTPS5PK β-myrcene, (-)-α-pinene Finola +++ +
CsTPS30PK CsTPS30PK β-myrcene Purple Kush +++ +
CsTPS6FN CsTPS6PK (E)-β-ocimene Finola +++ np
CsTPS7FN CsTPS7PK δ-selinene*Finola + +++
CsTPS8FN CsTPS8PK γ-eudesmol*, valencene Finola + +++
CsTPS9FN CsTPS9PK β-caryophyllene, α-humulene Finola + +++
CsTPS13PK CsTPS13PK (Z)-β-ocimene Purple Kush +++ +
CsTPS33PK CsTPS33PK α-terpinene, γ-terpinene Purple Kush +++ np
ŧ
Published in Gunnewich et al., 2008
*Product not compared to authentic standard.
np, no product detected. nd, no data available.
https://doi.org/10.1371/journal.pone.0173911.t002
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monoterpenes (-)-α-pinene (23%), (-)-limonene (17%), sabinene (15%), and (-)-β-pinene (8%).
The same product profile was identified when CsTPS5FN was transiently expressed in N.
benthamiana (S4 Fig). CsTPS5FN was somewhat unusual among TPS-b members in lacking any
obvious N-terminal plastidial targeting sequence. CsTPS5FN also produced minor amounts of
farnesene when incubated with FPP, making it the only member of the TPS-b subfamily to pro-
duce detectable sesquiterpenes. CsTPS6FN produced 97% (E)-β-ocimene with GPP, and the
remaining 3% of product was (Z)-β-ocimene. A TPS sequence found in Purple Kush,
CsTPS13PK, shares 95.5% amino acid sequence identity with CsTPS6FN. CsTPS13PK produces
94% (Z)-β-ocimene. A third TPS from Purple Kush, CsTPS33PK, produced two different mono-
terpenes, α-terpinene (61%) and γ-terpinene (39%) (Fig 4).
Functional characterization of CsTPSFN TPS-a subfamily members
Four TPS-a family members cloned as cDNAs from ‘Finola’, CsTPS4FN,CsTPS7FN,
CsTPS8FN, and CsTPS9FN, were expressed as recombinant proteins, proteins tested with GPP
and FPP and products identified by GC-MS (Fig 5A,Table 2). CsTPS4FN produced mostly
alloaromadendrene (52.3% of total products) with FPP (Fig 5C). The remaining products are a
mixture of five sesquiterpene olefins and two alcohols, including valencene, α-humulene, and
a product tentatively identified as palustrol. CsTPS4FN was also active with GPP, producing
minor amounts of myrcene (S5 Fig). CsTPS7FN produced 21 sesquiterpene olefins and two
sesquiterpene alcohols. Of these, products tentatively identified as δ-selinene and selina-6-en-
Fig 5. Representative GC-MS traces showing products of CsTPSFN TPS-a subfamily members. Black
traces show GC-MS total ion chromatogram (TIC) from CsTPS assays with FPP. Green trace, dotted line, in
(a) is representative terpene profiles from ‘Finola’ inflorescences. The right-hand region of the ‘Finola’ terpene
profile has been amplified 30-fold to facilitate comparison with the products of CsTPS7FN. (b) shows the trace
of CsTPS8FN after cold injection (40˚C inlet) onto a DB-wax column. (c) shows the trace for CsTPS4FN on an
HP-5 column. Peaks: n) β-caryophyllene, o) α-humulene, p) δ-selinene, q) selina-6-en-4-ol, r) valencene, s) γ-
eudesmol, t) alloaromadendrene, u) palustrol.
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4-ol make up 20.5% and 13.9% of the product profile, respectively. Very few of ‘Finola’ individ-
uals tested contained minor amounts of the products of CsTPS7FN (Fig 5A). The remaining
minor products each make up <10% of total sesquiterpene products. When incubated with
GPP, CsTPS7FN produced myrcene and limonene (S5 Fig). The most abundant product of
CsTPS8FN was initially identified as β-elemol (S6 Fig), which is often an artifact of heat-
induced rearrangement. Using a lower injection temperature of 40˚C, the β-elemol product
was no longer detected and was replaced by peaks corresponding to 11 sesquiterpene olefins
and three sesquiterpene alcohols. Of these, two of the major products were identified as γ-
eudesmol (19.8%) and valencene (19.6%) (Fig 5B). When CsTPS8FN was incubated with GPP
limonene and myrcene were detected (S5 Fig).
CsTPS9FN produced β-caryophyllene and α-humulene from FPP (Fig 5A). These two ter-
penes are always the most abundant sesquiterpenes in cannabis resin terpene profiles. The
CsTPS9FN enzyme produces these two sesquiterpenes in a ratio of approximately 2.5 to 1,
which is similar to the ratio of 2.4 +/- 0.2 to 1 observed in ‘Finola’ terpene profiles.
CsTPS transcripts are highly abundant in pistillate inflorescences
To determine to what extent the CsTPS genes described above contribute to the trichome ter-
pene profile, we performed RT-qPCR on transcripts of five CsTPS in glandular trichomes iso-
lated from pistillate flowers. Transcript levels of CsTPS1FN,CsTPS2FN,CsTPS3FN,CsTPS6FN,
and CsTPS9FN were examined in trichomes (S7 Fig) isolated from eight ‘Finola’ individuals
between two and four weeks post onset of flowering. These five CsTPS were chosen because
they have a single or at most two products, thus it was deemed more likely to be possible to
attempt correlating metabolite abundance with transcript abundances than would be possible
with the multiproduct CsTPS.
Of the eight individual plants, seven showed typical inflorescence terpene metabolite pro-
files. Surprisingly, one individual had no detectable inflorescence monoterpenes except for
traces of (E)-β-ocimene, although it did contain cannabinoids and sesquiterpenes in floral tri-
chomes (S8 Fig). In Fig 6A, metabolite levels of the target compounds are expressed as a pro-
portion of the total mono- or sesquiterpenes in each floral terpene extract. CsTPS2FN was the
most abundant of the six different TPS transcripts measured, and its major product, (+)-α-
pinene, was also the most abundant monoterpene on average in the eight plants examined.
Similarly, (E)-β-ocimene and the (E)-β-ocimene synthase CsTPS6FN were the least abundant
of all metabolites and transcripts measured, respectively. However, within transcript/metabo-
lite pairs, only the correlation between (-)-limonene and CsTPS1FN transcript level was sig-
nificant (Fig 6A). Correlation between metabolite level and transcript abundance was not
significant for any of the other metabolite/transcript pairs.
In addition, we measured the transcript abundance of the multiproduct monoterpene
synthase CsTPS5FN, to assess if its expression may contribute to terpene profiles in the resin.
CsTPS5FN transcripts were highly abundant in some individuals, comparable to the highest
transcript levels of any other CsTPS tested (Fig 6B). Transcript levels of this gene did not ex-
plain any of the lack of correlations between the five terpene-metabolite pairs tested above.
Additionally, plant X, which had no detectable monoterpenes, had moderate levels of CsTPS5FN
transcript. It appears that CsTPS5FN, while highly expressed, does not contribute to terpene accu-
mulation in ‘Finola’.
Discussion
The resin of C.sativa is rich in mono- and sesquiterpenes, which are of interest for their puta-
tive contributions to cannabis pharmacology [6]. Most studies of terpenes in cannabis have
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 12 / 20
focused on phytochemical composition for forensics and breeding, while less research has
gone into the molecular biology of terpene formation in cannabis. Knowledge of the genomics
and gene functions of terpene biosynthesis may facilitate genetic improvement of cannabis for
desirable terpene profiles. Using the hemp strain ‘Finola’ and its genome and transcriptome
resources [24], we identified early isoprenoid pathway genes as well as specific CsTPS genes
and their enzymes involved in the biosynthesis of nearly all of the different monoterpenes
identified in extracts of the cannabis inflorescences, which are densely covered with terpene
and cannabinoid accumulating glandular trichomes (Fig 1). One exception is terpinolene, for
which a CsTPS has not yet been identified. The terpene profiles of cannabis can be explained
Fig 6. Correlation analysis of metabolite abundance in inflorescence and transcript abundance for five CsTPS in isolated trichomes. (a) Data
are shown for five CsTPS/metabolite pairs each in eight ‘Finola’ individuals. Metabolites given with their relative abundance were those that match the
product of the corresponding CsTPS. Plant ‘X’ was not included in the left-most panel. Metabolite abundances are expressed as a proportion of thetotal
mono- or sesquiterpenes for each individual. Transcript abundances are calibrated normalized values comparedto two reference genes.
rho = Spearman rank correlation between transcript and metabolite abundances, p value indicates significance. (b) Transcript abundance of CsTPS5FN
in eight ‘Finola’ individuals.
https://doi.org/10.1371/journal.pone.0173911.g006
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by activities of both single-product and multi-product CsTPS. Individual ‘Finola’ plants
showed substantial variation in their profiles of mono- and sesquiterpenes. ‘Finola’ has few
monoterpene alcohols or ethers, such as linalool or geraniol, which are common in some can-
nabis strains.
It is reasonable to expect that there are additional CsTPS not described in this work, such as
aCsTPS that encodes a terpinolene synthase. Characterization of further TPS may also clarify
the poor correlation between TPS and the abundance of their products shown in Fig 6A. A
search of a new assembly of the Purple Kush genome, to which we recently had pre-publica-
tion access (Dr. Jonathan Page, personal communication), identified a total of 33 complete
CsTPSPK gene models and additional partial sequences (Fig 7). Purple Kush is a marijuana
strain which requires special research licensing to grow. Thus, characterization of this more
Fig 7. Maximum likelihood phylogeny for 33 TPS translated from gene models identified in the Cannabis
sativa Purple Kush genomic sequences. 41 published TPS sequences from other organisms were included for
comparison. Names of cannabis genes identified in this study are in bold. Gene names from Purple Kush followed
by an asterisk (*) represent biochemically characterized enzymes from Purple Kush transcriptome data. Their
nearest homologue in the genome was assigned the same gene ID when the sequences had >95% amino acid
identity. Branches with greater than 80% boostrap support are identified with a grey circle.
https://doi.org/10.1371/journal.pone.0173911.g007
Terpene synthases from Cannabis sativa
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comprehensive set of CsTPSPK will have to be completed in future work as it requires synthe-
sized genes.
Fig 7 indicates a set of putatively orthologous CsTPSFN and CsTPSPK genes, which may
contribute to overlapping terpene profiles in hemp and marijuana varieties. However, some
orthologous genes may have evolved different functions in different strains, and non-ortholo-
gous CsTPS may contribute to some of the same terpene products in different cannabis strains.
For example, α-pinene is a major component of strains reported as Purple Kush [37], but no
obvious orthologue of the α-pinene synthase CsTPS2 as identified in the ‘Finola’ and ‘Skunk’
strains was found in the Purple Kush genome (Fig 7). Another example is the set of apparently
non-orthologous single-product myrcene synthases, CsTPS3FN and CsTPS30PK identified in
‘Finola’ and Purple Kush, which only share 52.5% amino acid identity but produce the same
monoterpene. Also, not all CsTPS are expected to contribute to terpene accumulation in the
resin of cannabis inflorescences and some may function in a different context of the plant biol-
ogy. For example, CsTPS5FN is expressed in inflorescences and the recombinant enzyme pro-
duces a mixture of monoterpenes, but does not contribute substantially to the terpene profile
of the resin. This gene appears most closely related to MTS1 from hops (Fig 3) where the
encoded protein was inactive in vitro [38].
Cannabis inflorescences are densely covered with glandular trichomes, which are special-
ized to produce and accumulate terpenes [11]. Transcripts of several CsTPS genes (Fig 6A) are
abundant in trichomes isolated from mid-stage ‘Finola’ inflorescences. Transcripts associated
with early isoprenoid biosynthesis and especially the MEP pathway, which feeds into both
monoterpene and cannabionoid biosynthesis, were also abundant in trichomes (Fig 2B). Ses-
quiterpenes have been reported to be most abundant in early floral stages [39], and thus MEV
pathway transcripts may be more abundant at earlier stages of flower development. Different
DXS and HMGR genes were differentially expressed in roots relative to other parts of the
plant. Terpenes in the roots, if present in cannabis, may contribute to defense as reported in
other plant species [10]. In plants, DXS genes generally fall into two clades, of which DXS I
members are generally involved in primary metabolism, and DXS II members are often
induced in defense responses [40,41,42]. Abundance of cannabis DXS2 transcripts, which
clusters with the DXS II subfamily (S1 Fig), suggests defense related terpenoids in cannabis
roots and warrants future work on the cannabis root metabolome. We also observed high
FPPS transcript abundance in stamenate flowers and roots, resembling a previous finding that
Arabidopsis FPS1 was primarily expressed in flowers and roots compared to AtFPS2 [43].
Domestication and selective breeding can result in changes in terpene profiles and abun-
dance. For example, domestication can lead to a decrease in the quantity or variability of ter-
penes [44,45,46]. Cannabis, especially marijuana, has been domesticated for thousands of
years for increased resin volume and potency [2,47] and as a result profiles and ecological
roles of terpenes in ancestral (i.e., undomesticated) cannabis are unknown. The present study
highlights the large number of CsTPS genes and the diverse products of the encoded TPS
enzyme activities, which contribute to the complex terpene profiles of cannabis. The knowl-
edge of multigene nature of the CsTPS family and the often multiple products of the encoded
enzymes will be critical when selecting or breeding, or improving plants by genome editing,
for particular terpene profiles for standardized cannabis varieties. While cannabinoid-free
individuals have occasionally been reported [48], we are not aware of any reports in the litera-
ture of terpene-free cannabis. In this study, we observed a single monoterpene-free individual,
which however still contained cannabinoids and sesquiterpenes. This observation implies that
biosynthesis of the different classes of terpenoid metabolites are independently regulated. The
fact that terpenes have persisted throughout domestication as a substantial and diverse compo-
nent of cannabis resin highlights their significance for human preferences.
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 15 / 20
GenBank accessions
GenBank accession numbers for the terpene synthases described in this paper are CsTPS1FN:
KY014557, CsTPS2FN: KY014565, CsTPS3FN: KY014561, CsTPS4FN: KY014564, CsTPS5FN:
KY014560, CsTPS6FN: KY014563, CsTPS7FN: KY014554, CsTPS8FN: KY014556, CsTPS9FN:
KY014555, CsTPS11FN: KY014562, CsTPS12PK: KY014559, CsTPS13PK: KY014558. Acces-
sion numbers for genes in the MEP pathway are CsDXS1: KY014576, CsDXS2: KY014577,
CsDXR: KY014568, CsMCT: KY014578, CsCMK: KY014575, CsHDS: KY014570, CsHDR:
KY014579. Accession numbers for genes in the MEV pathway are CsHMGS: KY014582,
CsHMGR1: KY014572, CsHMGR2: KY014553, CsMK: KY014574, CsPMK: KY014581,
CsMPDC: KY014566, CsIDI: KY014569. Prenyltransferase accession numbers are CsGPPS.
ssu1: KY014567, CsGPPS.ssu2: KY014583, CsFPPS1: KY014571, CsFPPS2: KY014580. Acces-
sion numbers for genomic regions containing putative terpene synthases from Purple Kush are
CsTPS1PK: KY624372, CsTPS4PK: KY624361, CsTPS5PK: KY624374, CsTPS6PK: KY624363,
CsTPS7PK: KY624368, CsTPS8PK: KY624352, CsTPS9PK: KY624366, CsTPS10PK: KY624347,
CsTPS11PK: KY624348, CsTPS12PK: KY624349, CsTPS13PK: KY624350, CsTPS14PK:
KY624351, CsTPS15PK: KY624353, CsTPS16PK: KY624354, CsTPS17PK: KY624355,
CsTPS18PK: KY624356, CsTPS19PK: KY624357, CsTPS20PK: KY624358, CsTPS21PK:
KY624360, CsTPS22PK: KY624360, CsTPS23PK: KY624362, CsTPS24PK and CsTPS25PK:
KY624364, CsTPS26PK and CsTPS27PK: KY624365, CsTPS30PK: KY624367, CsTPS31PK:
KY624369, CsTPS32PK: KY624370, CsTPS33PK: KY624371, CsTPS34PK: KY624373,
CsTPS35PK: KY624375.
Supporting information
S1 Table. Primers used to clone TPS genes.
(XLSX)
S2 Table. qPCR primers.
(XLSX)
S3 Table. Accession numbers of TPS sequences used in tblastn and to construct phylog-
eny.
(XLSX)
S1 Fig. DXS Phylogeny. Maximum likelihood phylogeny of DXS enzymes. Cannabis sativa
genes are in bold. DXS of other species included are from: At: Arabidopsis thaliana; Pt: Populus
trichocarpa; Os: Oryza sativa; Cr: Chlamydomonas reinhardtii; Mt: Medicago truncatula; Pa:
Picea abies.
(PNG)
S2 Fig. Representative GC-MS traces of myrcene synthase products.
(PNG)
S3 Fig. Mass spectra of TPS products. Labels “Peak a” through “Peak u” correspond to peaks
labeled in Figs 4and 5.
(PNG)
S4 Fig. Products of CsTPS5FN expressed in E.coli and Nicotiana benthamiana.Black trace
represents products of recombinant enzyme expressed in E.coli, green trace represents prod-
ucts of recombinant enzyme expressed in N.benthamiana. Leaf images (right) show GFP posi-
tive expression control.
(PDF)
Terpene synthases from Cannabis sativa
PLOS ONE | https://doi.org/10.1371/journal.pone.0173911 March 29, 2017 16 / 20
S5 Fig. Products of CsTPS with alternative substrates. Members of TPS-a with GPP as sub-
strate are on the left-hand side. Members of TPS-b with FPP as substrate are on the right.
(PDF)
S6 Fig. Hot vs. cold injection of CsTPS8FN products. Top panel represents total ion chro-
matogram (TIC) with the injection port at 250˚C on a DB-Wax column. The bottom panel
represents TIC with the injection port at 40˚C, using the same program and the same column.
(PDF)
S7 Fig. Isolated glandular trichome heads.
(PDF)
S8 Fig. Terpene chemotypes of ‘Finola’ flowers. Abundance of five metabolites or metabolite
pairs is measured relative to floral weight and an internal standard. Error bars indicate the
standard deviation of five metabolite samples taken from each individual.
(PDF)
S9 Fig. Amino acid sequence alignment of functionally characterized CsTPS enzymes.
(PDF)
Acknowledgments
We thank We thank Mr. Jan Slaski (Alberta Innovates Technology Futures) for hemp seeds;
Mr. Mack Yuen (UBC), Ms. Lina Madilao (UBC), and Dr. Melissa Mageroy (UBC) for techni-
cal advice; and Dr. Justin Whitehill (UBC) and Dr. Sandra Irmisch (UBC) for comments on
the manuscript.
Author Contributions
Conceptualization: JB JEP JKB.
Formal analysis: JKB.
Funding acquisition: JB JKB.
Investigation: JB JKB.
Project administration: JB JKB.
Resources: JB JEP.
Supervision: JB JEP.
Writing – original draft: JB JKB.
Writing – review & editing: JB JEP JKB.
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