Abstract
The genus Striga, also called "witchweed", is a member of the family Orobanchaceae, which is a major family of root-parasitic plants. Striga can lead to the formation of seed stocks in the soil and to explosive expansion with enormous seed production and stability once the crops they parasitize are cultivated. Understanding the molecular mechanism underlying the communication between Striga and their host plants through natural seed germination stimulants, "strigolactones (SLs)", is required to develop the technology for Striga control. This review outlines recent findings on the SL perception mechanism, which have been accumulated in Striga hermonthica by the similarity of the protein components that regulate SL signaling in nonparasitic model plants, including Arabidopsis and rice. HTL/KAI2 homologs were identified as SL receptors in the process of Striga seed germination. Recently, this molecular basis has further promoted the development of various types of SL agonists/antagonists as seed germination stimulants or inhibitors. Such chemical compounds are also useful to elucidate the dynamic behavior of SL receptors and the regulation of SL signaling.