Licorice, revered in traditional Chinese medicine as the "Elderly Master" and classified as a top-grade herb in the Shen Nong's Classic of Materia Medica, plays a pivotal role in herbal formulations by harmonizing the effects of other ingredients, stabilizing their potency, and ensuring balanced prescriptions.

In modern applications, licorice roots contain bioactive compounds such as glycyrrhizin and flavonoids, which exhibit anti-inflammatory, antiviral, and antioxidant properties. Widely used in pharmaceuticals, health supplements, and as a natural sweetener and flavor enhancer in food and beverages, its medicinal varieties primarily include Glycyrrhiza uralensis, Glycyrrhiza inflata, and Glycyrrhiza glabra. However, while most research has focused on the herb's surface characteristics, genetic differences at the whole-genome level remain largely uncharted.

To bridge this gap, a research team led by Prof. WANG Ying from the South China Botanical Garden of the Chinese Academy of Sciences, in collaboration with researchers from Hainan University, has decoded high-quality reference genomes for the three key species. Published in The Plant Journal, the study reports genome sizes of 425 Mb for G. uralensis, 447 Mb for G. inflata, and 423 Mb for G. glabra.

Through whole-genome alignment, the researchers identified collinear relationships and structural variations among the three species. Notably, presence/absence variation (PAV) genes were found to be predominantly enriched in secondary metabolic pathways, offering critical genetic resources for analyzing the synthesis and regulation of both shared and unique active ingredients across the licorice species.

Leveraging these structural variations alongside transcriptome data from different tissues and developmental stages, the team constructed a regulatory network for glycyrrhizin biosynthesis. They confirmed that three transcription factors—GibHLH9, GibHLH53, and GibHLH174—play key roles in promoting glycyrrhizin production.

Additionally, the researchers mapped genes involved in the biosynthetic pathways of licochalcone A (LCA) and glabridin, verifying that the enzyme GiOMT17 catalyzes a critical step in LCA synthesis. The study attributes the differential accumulation of signature flavonoids in the three species to the emergence of species-specific genes and variations in gene expression patterns.

This genomic breakthrough sheds new light on the genetic basis of licorice's medicinal properties, potentially accelerating the development of improved varieties and targeted herbal therapies.