Inexpensive fast-growing plants have been transformed into factories that churn out an important antimalarial drug.

Artemisinin is the only proven malaria treatment, with hundreds of millions of doses taken every year. The sweet wormwood plant (Artemisia annua) produces a precursor of the compound, artemisinic acid, only in low quantities, and is expensive to grow. To scale-up production, a team led by Ralph Bock at the Max Planck Institute of Molecular Plant Physiology in Potsdam-Golm, Germany, inserted genes for artemisinic acid synthesis into tobacco plants' chloroplasts — abundant organelles that have their own DNA. By adding 'accessory genes' that make artemisinic acid production more efficient, they created a line that pumps out 120 milligrams of artemisinic acid per kilogram of biomass.

The researchers estimate that the world's demand for the drug could be met with just 200 square kilometres of tobacco fields — an area smaller than the city of Boston.

eLife 5, e13664 (2016)