Chinese Researchers Map Greek Oregano Genome for Better Agriculture

Oregano belongs to the Lamiaceae family, which includes many aromatic and medicinal plants. Its essential oil (EO) has attracted increasing attention because of its antimicrobial, antioxidant, and flavor-enhancing properties, particularly as natural alternatives are sought in food, agriculture, and livestock production. However, earlier oregano genome resources were fragmented, limiting studies of chromosome structure, gene family evolution, and coordinated regulation of terpenoid pathways. The biosynthesis of thymol and carvacrol involves multiple enzymes, transcription factors, and hormone-related signals that have not been fully characterized. Due to these challenges, in-depth research is needed to clarify the genomic and regulatory basis of EO production in Greek oregano.

Researchers from Nanjing Agricultural University, the Kunming Institute of Botany, Chinese Academy of Sciences, Sichuan Agricultural University, Gansu Agricultural University, and Zhiguang Cryptic (Jiangsu) Biotechnology Co., Ltd. reported (DOI: 10.1093/hr/uhag030) the study on January 30, 2026, in Horticulture Research. The article presents a chromosome-level genome assembly of Greek oregano (Origanum vulgare subsp. hirtum) and uses it to investigate genome evolution, high-EO mutants, JA-mediated regulation, and transcriptional control of terpenoid biosynthesis.

The team assembled a 709.74-megabase genome anchored to 15 chromosomes, with a scaffold N50 of 46.36 megabases and 30,891 predicted protein-coding genes. Comparative genomic analysis suggested that whole-genome duplication (WGD) contributed to the diversification of secondary metabolism in Lamiaceae, including pathways related to terpenoid biosynthesis. To connect genome structure with EO traits, the researchers developed a rapid screening method based on oregano EO's antibacterial activity against Escherichia coli.

From a gamma-ray-induced mutant population, they identified 51 candidate high-EO mutants. One mutant, HEO1, reached an EO content of 5.12%, compared with 2.72% in wild-type plants, and showed higher carvacrol levels. Transcriptome analysis revealed strong enrichment of α-linolenic acid metabolism and JA biosynthesis. Exogenous JA treatment further increased EO yield by 27.95% and upregulated key biosynthetic genes, including OvSDR1, OvCYP71D178, OvCYP71D507, OvCYP76A300, and OvCYP76S40.

The authors said the study moves oregano research from observing high-oil traits to identifying the molecular switches that help produce them. They said OvbHLH13 is a JA-inducible transcription factor involved in terpenoid biosynthesis. Through yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), and dual-luciferase assays, the team showed that OvbHLH13 directly binds to and activates the promoter of OvSDR1, a key gene linked to thymol and carvacrol production. This finding connects JA signaling with the transcriptional regulation of EO biosynthesis.

These findings provide a genomic foundation for breeding Greek oregano varieties with higher EO yield and improved bioactive compound profiles. The chromosome-level genome will support studies of gene family expansion, structural variation, and metabolic regulation across other aromatic Lamiaceae plants. The identification of the JA-inducible transcription factor OvbHLH13, which directly activates OvSDR1 in the terpenoid biosynthesis pathway, offers a potential molecular target for marker-assisted selection, functional genomics, and precision breeding.

Beyond oregano, the work may guide the improvement of medicinal and culinary herbs whose value depends on specialized metabolites, supporting natural product development, sustainable agriculture, EO-based food preservation, and plant biotechnology.