A team of geneticists from the John Innes Centre and the Chinese Academy of Sciences has produced the first high-quality genomic sequence for the Chinese skullcap (Scutellaria baicalensis), one of the 50 fundamental herbs used in Traditional Chinese Medicine.
The Chinese skullcap (Scutellaria baicalensis). Image credit: Andrey Korzun / CC BY-SA 3.0.
The Chinese skullcap is a species of flowering plant in the mint family Lamiaceae found in China, Korea, Mongolia and Siberia.
Also known as the Baikal skullcap, this plant is very chemically complex and is full of antioxidants known as flavones (such as wogonin and baicalin).
The Chinese skullcap is important in Traditional Chinese Medicine where preparations of its dried roots, ‘Huang Qin,’ are used to treat many medical conditions: diarrhea, dysentery, hypertension, hemorrhaging, insomnia, inflammation and respiratory infections. Extracts from the plant kill liver cancer and leukemia cells, but human data are lacking.
Despite the commercial interest and increasing demand for the plant, improvements through breeding have been limited by a lack of genome information.
“This plant makes the bioactive compounds in the root, which means you have to wait three years for the plant to get big enough and of course in taking the root you destroy the plant,” said John Innes Centre’s Professor Cathie Martin, senior author of the study.
“We’ve screened some members of the mint family that make similar compounds in the leaves which means you could get more sustainable therapeutics taken in a different way.”
Professor Martin and colleagues took DNA from a single plant at the Shanghai Chenshan Botanical Garden, China, and used a combination of sequencing strategies to assemble 93% of the genome organized into 9 pseudochromosomes.
Comparison of the sequence to those of closely related species, Sesamum indicum and Salvia splendens, revealed how the specialized metabolic pathway for the synthesis of bioactive compounds evolved in the Scutellaria genus.
“When we started getting the analysis back on the genome sequence it was like a revelation — it showed at a fundamental level how the pathway to valuable compounds evolved,” Professor Martin said.
“The sequence is so good that it can improve the understanding of all the other genome sequences in the mint family. This is a large family of plants that is hugely important in Traditional Chinese Medicine and flavorings.”
The results appear in the journal Molecular Plant.
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Qing Zhao et al. The Reference Genome Sequence of Scutellaria baicalensis Provides Insights into the Evolution of Wogonin Biosynthesis. Molecular Plant, published online April 14, 2019; doi: 10.1016/j.molp.2019.04.002
