Plants in the Meliaceae family produce a wide array of terpenes—structurally diverse and bioactive compounds that contribute to their distinctive scents, medicinal properties, and economic value. Despite the remarkable terpene diversity found in these species, the role of whole-genome duplication (WGD) in shaping this chemical richness has remained unclear.

A new study published in Molecular Horticulture on April 9 unlocks the secrets of terpene diversity despite gene loss in Meliaceae plants.

Researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) and the Kunming Institute of Botany (KIB) of the Chinese Academy of Sciences have successfully assembled a high-quality genome of Aglaia odorata, commonly known as the Chinese perfume tree. Their findings reveal the unexpected evolutionary mechanisms behind the plant's exceptional terpene production, including a lineage-specific whole-genome triplication (WGT) event. The study shows how transcriptional upregulation can compensate for gene loss, ultimately driving chemical diversity.

The researchers conducted a comparative analysis of representative Meliaceae species. Through the integration of comparative genomics, transcriptomics, metabolomics, and molecular assays, they produced a high-quality genome assembly of Aglaia odorata and uncovered the mechanisms underlying its elevated terpene diversity.

This study is the first to report a lineage-specific WGT event in the Meliaceae family, which includes mahogany and neem. The researchers also identified a key transcription factor, AodERF27, which directly activates one of the most highly expressed terpene synthase genes, AodTPS26, establishing a direct link between transcriptional regulation and terpene diversity.

"We found a paradox," said YANG Yongping of XTBG. "Aglaia odorata produces exceptionally high levels of terpenes, yet its terpene synthase gene family has actually contracted following genome triplication. The answer lies in selective gene retention and powerful transcriptional upregulation."

The study demonstrates how whole-genome duplication events drive the diversification of plant secondary metabolites through gene dosage effects, expression reprogramming, and transcriptional regulatory network remodeling. It offers novel insights into mechanisms of metabolic innovation in plants.