Nat. Chem. Biol. 12, 724–729 (2016)
The plant hormone strigolactone was given its name as, when exuded from roots, it induces germination of seeds from parasitic Striga spp. Several species of Striga, commonly known as witchweeds, are parasitic, and are important pathogens of cereal crops in Africa and elsewhere. These species attach to roots and take up the circulating nutrients, reducing early growth of the crops. A team led by Peter McCourt from Toronto, Canada, has identified a promising chemical that interferes with strigolactone perception mechanisms and blocks the germination of the parasite.
As strigolactones are also involved in plant development, the researchers developed a high-throughput chemical screen in transgenic Arabidopsis seedlings with artificially elongated hypocotyls. Strigolactone reduces growth and thus an antagonist should restore hypocotyl elongation. A secondary germination-based screen on wild-type Arabidopsis and other assays confirmed the antagonistic effect. The most promising molecule, renamed soporidine, binds to strigolactone receptors in Arabidopsis and Striga, but does not affect the growth of monocot grasses.
Striga plants produce an impressive number of tiny seeds that can stay dormant in the soil and contaminate fields for years. It is a significant problem in Africa, as the affected crops include tropical and subtropical cereals. Soporidine has the ability to block Striga germination without affecting grass hosts and so could be used in agriculture to coat seeds and, ultimately, protect yields.