To identify candidate terpene-producing genes in R. lindenbergiana, its transcriptomes from the One thousand plant (OneKP) project (https: //sites.google.com/a/ualberta.ca/onekp/) were searched for TPS and MTPLS genes using a HMMER method (Finn et al., 2015). A single TPS homolog designated as RlTPS1 was identified. RlTPS1 appears to be partial sequence. The protein it encodes is most similar to MpDTPS5 from M. polymorpha (Supplemental Figure S1). Because MpDTPS5 is a putative diterpene synthase (Bowman et al., 2017), we hypothesized that RlTPS1 is also a diterpene synthase. In contrast, a total of 12 MTPSL genes were found. Five of them that appeared to be full-length genes were designated RlMTPSL1-5. A cDNA for each of the five genes was cloned by reverse transcription PCR (RT-PCR) and verified by sequencing.
RlMTPSL1-5 encode proteins of 391–441 amino acids in length (Fig. S1). Sequence similarities among the five RlMTPSLs range from 38% (RlMTPSL1 and RlMTPS4) to 71% (RlMTPSL2 and SlMTPSL3). Sequence alignment showed that they had DDXXD and NSE/DTE conserved motifs, which were reported to be involved in ionization of the substrate and catalysis (Chen et al., 2011). GenBank accession numbers for the five RlMTPSL genes are MZ367362-MZ367366.