Aristolochic acids (AAs) and their derivatives exist in multiple Aristolochiaceae species which had been or are being used as medicinal materials. During the past decades, AAs have received increasing attention due to their nephrotoxicity and carcinogenecity. Elimination of AAs in medicinal materials using biotechnological approaches is important to improve medication safety. However, it has not been achieved because of the limited information of AA biosynthesis available. Here, we report a high-quality reference-grade genome assembly of the AA-containing vine, Aristolochia contorta. Total size of the assembly is 209.27 Mb, which is assembled into 7 pseudochromosomes. Synteny analysis, Ks distribution and 4DTv suggest absences of whole-genome duplication events in A. contorta after the angiosperm-wide WGD. Based on genomic, transcriptomic and metabolic data, pathways and candidate genes of benzylisoquinoline alkaloid (BIA) and AA biosynthesis in A. contorta were proposed. Five O-methyltransferase genes, including AcOMT1–3, AcOMT5 and AcOMT7, were cloned and functionally characterized. The results provide a high-quality reference genome for AA-containing species of Aristolochiaceae. It lays a solid foundation for further elucidation of AA biosynthesis and regulation and molecular breeding of Aristolochiaceae medicinal materials.

Salvia miltiorrhiza is well-known for its clinical practice in treating heart and cardiovascular diseases. Its roots used for traditional Chinese medicine materials are usually brick-red due to accumulation of red pigments, such as tanshinone IIA and tanshinone I. Here we report a S. miltiorrhiza line (shh) with orange roots. Compared with the red roots of normal S. miltiorrhiza plants, the contents of tanshinones with a single bond at C-15,16 were increased, whereas those with a double bond at C-15,16 were significantly decreased in shh. We assembled a high-quality chromosome-level genome of shh. Phylogenomic analysis showed that the relationship between two S. miltiorrhiza lines with red roots were closer than their relationship with shh. It indicates that shh could be not the mutant of an extant S. miltiorrhiza line with red roots. Comparative genomic and transcriptomic analyses showed that a 1.0kb DNA fragment was deleted in shh Sm2OGD3m. Complementation assay showed that overexpression of intact Sm2OGD3 in shh hairy roots recovered furan D-ring tanshinone accumulation. Consistently, in vitro protein assay showed that Sm2OGD3 catalyzed the conversion of cyptotanshinone, 15,16-dihydrotanshinone I and 1,2,15,16-tetrahydrotanshinone I into tanshinone IIA, tanshinone I and 1,2-dihydrotanshinone I, respectively. Thus, Sm2OGD3 functions as tanshinone 15,16-dehydrogenase and is a key enzyme in tanshinone biosynthesis. The results provide novel insights into the metabolic network of medicinally important tanshinone compounds.

In Cambodia, medicinal plants are often used to treat various illnesses. However, the identities of many medicinal plants remain unknown. In this study, we collected 50 types of traditional Cambodian medicinal plants that could not be identified by their appearance from a domestic market. We utilized the DNA barcoding technique, combined with the literature survey, to trace their identities. In the end, 33 species were identified at the species level and 7 species were identified at the genus level. The ethnopharmacological information of 33 medicinal plants was documented. The DNA barcoding technique is useful in the identification of medicinal plants with no previous information.