A Germination Stimulant for Parasitic Flowering Plants from Sorghum bicolor, a Genuine Host Plant

A germination stimulant for the seeds of angiospermous root parasites was isolated from root exudates of Sorghum bicolor (L.) cv. Haygrazer, a genuine host plant for Striga asiatica and Striga hermonthica. A preliminary suggestion for the chemical structure of the new stimulant sorgolactone, based on spectroscopic data, is closely related to (+)-strigol, a germination stimulant isolated from the false host plant Gossypium hirsutum. The new compound is more active than strigol in stimulating seeds of the parasites.