Mining the diversity of diterpenoids in Coleus

Lin, Ruoxi (2025) Mining the diversity of diterpenoids in Coleus. Doctoral thesis, University of East Anglia.

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Abstract

Species from the genus Coleus Lour. in the Lamiaceae family are recognized for their ethnobotanical importance, with their pharmaceutical properties often attributed to diterpenes. Due to frequent synonymy used for medicinally important lineages and the absence of clear infrageneric characters, the link between phytochemistry and phylogeny is poorly understood in the genus Coleus, which has limited exploration of its medicinal potential.

Over 20 species from Coleus are reported to produce only abietane-diterpenes, but Coleus comosus is reportedly capable of synthesizing three more types of diterpenes: clerodanes, halimanes, and labdanes, making C. comosus a promising model for exploring the chemodiversity in the genus. Through genomic and phylogenetic analyses, an accession labelled “C. comosus/Plectranthus ornatus” was shown to be an infertile interspecific hybrid between C. comosus and its sister species Coleus neochilus. Both the hybrid accession and C. comosus produced clerodane and abietane diterpenoids. However, there were considerable differences in their glandular trichomes, which is the accumulation sites for these diterpenoids.

The hybrid provided two sets of genomes for comparative analyses with an array of tandemly replicated genes encoding diterpene cyclases present in both subgenomes, with the early replications having occurred before the divergence of the parental species. Upon heterologous expression, two enzymes encoded by the replicated genes yielded clerodane diterpene scaffolds, while two other enzymes produced novel diterpene scaffolds, rare in Lamiaceae. Preliminary investigations of residues important for determining diterpene cyclase functionality showed that functional diversification involved changes in both catalytic and non-catalytic residues, probably involving transition through a clerodane diterpene cyclase as an intermediate state. Taken together, the data suggest that clerodane diterpenes might have a wide presence in closely related species, an idea confirmed by the detection of clerodanes in numerous herbarium specimens from the Coleus lineage, suggesting that diterpenes could serve as chemotaxonomic markers within the genus Coleus.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	23 Jul 2026 12:54
Last Modified:	23 Jul 2026 12:54
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103948
DOI:

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