Recent trends in the elucidation of complex triterpene biosynthetic pathways in horticultural trees

Triterpene (C30 isoprene compounds) represents the most structurally diverse class of natural products and has been extensively exploited in the food, medicine and industrial sectors. Decades of research on medicinal triterpene biosynthetic pathways have revealed their roles in stress tolerance and shaping microbiota. However, the biological function and mechanism of triterpenes are not fully identified. Even this scientific window narrows down for horticultural trees. The lack of knowledge and a scalable production system limits the discovery of triterpene pathways. Recent synthetic biology research revealed several important biosynthetic pathways that define their roles and address many societal sustainability challenges. Here, I review the chemical diversity and biosynthetic enzymes involved in triterpene biosynthesis of horticultural trees. This review also outlines the integrated Design-Build-Test-Learn (DBTL) pipelines for the discovery, characterization and optimization of triterpene biosynthetic pathways. Further, these DBTL components share many fundamental and technical difficulties, highlighting opportunities for interdisciplinary collaboration between researchers worldwide. This advancement opens up unprecedented opportunities for the bioengineering of triterpene compounds towards development and scaleup processes.