Terpenoids represent the most diverse class of specialized metabolites in plants, yet they originate from just two simple precursors—isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). A comprehensive review published in Engineering traces how technological advances are transforming our understanding of these compounds, from basic biosynthesis to their roles in plant-environment interactions.

The study of terpene biosynthesis dates back to the early 20th century, with Nobel laureate Otto Wallach contributing to understanding terpene structural diversity. Major breakthroughs occurred in the 1950s when researchers discovered that IPP and DMAPP serve as universal precursors for all terpenoids, leading to identification of the mevalonic acid (MVA) and methylerythritol phosphate (MEP) pathways. Today, terpene biosynthesis can be broadly divided into two stages: the formation of upstream carbon–hydrogen scaffolds and the downstream modification of these scaffolds.

Recent years have witnessed significant progress in elucidating the molecular details of terpenoid production. The review highlights that after the formation of C5 building blocks from both MEP and MVA pathways, isoprenyl diphosphate synthase (IDS) and terpene synthases (TPSs) generate diverse terpenoid scaffolds. Notably, geranylfarnesyl diphosphate synthases (GFPPSs, C25) have only recently been functionally characterized in plants. Research by Ma et al. provided genetic evidence that GFPPSs are responsible for sesterterpene biosynthesis in Arabidopsis, revealing that disruption of the GFPPS step led to increased accumulation of geranylgeranyl diphosphate (GGPP)-derived terpenes, indicating pathway competition.

The integration of multi-omics technologies has substantially accelerated pathway elucidation. Gene coexpression analysis remains a workhorse approach for candidate gene discovery, while expanding genomic resources have provided valuable insights into the evolutionary origins and diversification of terpenoid metabolism. The publication of reference genomes for two yew species in 2021 reignited efforts to fully elucidate the Taxol biosynthetic pathway. Subsequently, five research groups independently identified key upstream cytochrome P450-catalyzed reactions, enabling reconstruction of a heterologous biosynthetic pathway producing baccatin III, an industrial precursor for Taxol.

The review also examines how researchers are increasingly focusing on the functions of metabolic genes and compounds within plants themselves, as well as their interactions with the environment. For example, steroidal glycoalkaloids contribute to pest resistance in Solanaceae plants, while strigolactones regulate shoot branching and mediate root–rhizosphere interactions. Recent work identified strigolactone transporters in sorghum, SbSLT1 and SbSLT2, which belong to the ATP-binding cassette (ABC) transporter family. Knockout of these transporters significantly reduced Striga parasitism while maintaining normal plant growth and yield.

Artificial intelligence is emerging as a promising direction with the potential to fundamentally transform terpenoid research. Machine learning applications in chemical identification, mass spectrometry imaging, and metabolic engineering optimization are showing success. Deep-learning systems such as AlphaFold for protein structure prediction have already accelerated research. However, the availability of high-quality, standardized training datasets represents one of the most significant limiting factors for successful machine learning application.

The review concludes that the field has progressed from stepwise identification of single enzymes to concurrent dissection of entire pathways, often encompassing more than ten reactions. The next priorities beyond pathway mapping are precisely enhancing in planta accumulation of target metabolites and defining their physiological and ecological functions—establishing prerequisites for deploying medicinal plants as versatile chassis for synthetic biology.

The paper “Plant Terpenoid Diversity: From Pathway Elucidation to Ecological Functions,” is authored by Xiaochen Wang, Guodong Wang. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.11.021. For more information about Engineering, visit the website at https://www.sciencedirect.com/journal/engineering.