Strigol induces germination of the facultative parasitic plant in the absence of nitrate ions.

Root parasitic plants in the family Orobanchaceae, such as and spp., infest major crops worldwide, leading to a multibillion-dollar loss annually. Host-derived strigolactones (SLs), recognized by a group of α/β hydrolase receptors (KAI2d) in these parasites, are important determinants for germinating root parasitic plants near the roots of host plants. , a facultative hemiparasitic Orobanchaceae plant, can germinate and grow in the presence or absence of the host and can also exhibit root chemotropism to host-derived SLs that are perceived via KAI2d. However, the importance of SLs in germination remains unclear. In this study, we found that germination of was suppressed in the absence of nitrate ions and that germination of was promoted by exogenous strigol, an SL, under such conditions. We propose a model in which may select either independent living or parasitism in response to ambient nitrogen conditions and host presence.