Biosynthesis of sesquiterpene lactones in pyrethrum (Tanacetum cinerariifolium).

The daisy-like flowers of pyrethrum (Tanacetum cinerariifolium) are used to extract pyrethrins, a botanical insecticide with a long history of safe and effective use. Pyrethrum flowers also contain other potential defense compounds, particularly sesquiterpene lactones (STLs), which represent problematic allergenic residues in the extracts that are removed by the pyrethrum industry. The STLs are stored in glandular trichomes present on the pyrethrum achenes, and have been shown to be active against herbivores, micro-organisms and in the below-ground competition with other plants.