Influx and Efflux of Strigolactones Are Actively Regulated and Involve the Cell-Trafficking System

Strigolactones (SLs) are plant hormones that regulate different aspects of plant development. In roots, SLs are involved in the regulation of lateral-root formation and they induce root-hair elongation (Kapulnik et al., 2011). They are also exuded from plant roots and act as stimulators of parasitic and symbiotic (e.g., arbuscular mycorrhizae) interactions. SLs are perceived in plants by a specific reception system that consists of several interacting proteins (reviewed by Al-Babili and Bouwmeester, 2015).