Artemisinin is highly effective against multidrug-resistant strains of Plasmodium falciparum, the aetiological agent of the most severe form of
malaria. However, a low level of accumulation of
artemisinin in Artemisia annua is a major limitation for its production and delivery to
malaria endemic areas of the world. While several strategies to enhance
artemisinin have been extensively explored, enhancing storage capacity in trichome has not yet been considered. Therefore, trichome density was increased with the expression of β-
glucosidase (bgl1) gene in A. annua through Agrobacterium-mediated transformation. Transgene (bgl1) integration and transcript were confirmed by molecular analysis. Trichome density increased up to 20% in leaves and 66% in flowers of BGL1 transgenic plants than Artemisia control plants. High-performance liquid chromatography, time of flight mass spectrometer data showed that
artemisinin content increased up to 1.4% in leaf and 2.56% in flowers (per g DW), similar to the highest yields achieved so far through metabolic engineering.
Artemisinin was enhanced up to five-fold in BGL1 transgenic flowers. This study opens the possibility of increasing
artemisinin content by manipulating trichomes' density, which is a major reservoir of
artemisinin. Combining biosynthetic pathway engineering with enhancing trichome density may further increase
artemisinin yield in A. annua. Because oral feeding of Artemisia plant cells reduced
parasitemia more efficiently than the purified
drug, reduced drug resistance and cost of prohibitively expensive purification process, enhanced expression should play a key role in making this valuable
drug affordable to treat
malaria in a large global population that disproportionally impacts low-socioeconomic areas and underprivileged children.