GC-MS analysis of hydrophobic root exudates of sorghum and implications on the parasitic plant Striga asiatica.

Striga asiatica is a parasitic angiosperm that responds to germination stimulants produced by host plants, including many grasses. GC-MS analyses of hydrophobic root exudates of sorghum revealed the root exudates to be composed of fatty acids, resorcinol, and a series of structurally related hydroquinones, three of which were previously unknown. High yields of resorcinol and the hydroquinone series were detected in sorghum. At least one of the hydroquinones induces germination in Striga, and the resorcinol is thought to stabilize the hydroquinones in the soil. The previously unknown series of hydroquinones offers insight into the possible biosynthesis of the components of the exudate and their possible importance in initiating Striga germination.