Sweet wormwood, Artemisia annua, is the sole source of a potent antimalarial compound called artemisinin. The drug is recommended by the World Health Organization (WHO) as a treatment for malaria caused by Plasmodium falciparum, but supply is currently well below demand. Now, researchers in China have for the first time published a high-quality genome sequence for A. annua, and genetically modified the plant to produce much higher levels of artemisinin.
“Nearly half of the world’s population is at risk of malaria,” study coauthor Kexuan Tang of Shanghai Jiao Tong University says in a statement. “Our strategy for the large-scale production of artemisinin will meet the increasing demand for this medicinal compound and help address this global health problem.”
A. annua produces artemisinin at a rate of only about 0.1 percent to 1 percent of the dry weight of its leaves. Alternative approaches to producing the compound have mainly focused on making the drug through other means, for example, via yeast cells engineered to produce a biochemical precursor to artemisinin. But that system is expensive and is not yet ready to replace plant-based production.
In the current study, Tang and his colleagues put together a high-quality draft assembly of the A. annua genome and used it to identify the genetic components of artemisinin biosynthesis. By increasing the expression of three genes involved in this pathway, the team was able to grow plants with much higher levels of artemisinin—up to 3.2 percent of the leaves’ dry weight.