Rice DWARF14 acts as an unconventional hormone receptor for strigolactone

Strigolactones (SLs) act as an important class of phytohormones to regulate plant shoot branching, and also serve as rhizosphere signals to mediate interactions of host plants with soil microbes and parasitic weeds. SL receptors in dicots, such as DWARF14 in Arabidopsis (AtD14), RMS3 in pea, and ShHTL7 in Striga, serve as unconventional receptors that hydrolyze SLs into a D-ring-derived intermediate CLIM and irreversibly bind CLIM to trigger SL signal transduction. Here, we show that D14 from the monocot rice can complement Arabidopsis d14 mutant and interact with the SL signaling components in Arabidopsis. Our results further reveal that rice D14, similar to SL receptors in dicots, also serves as an unconventional hormone receptor that generates and irreversibly binds the active form of SLs. These findings uncover the conserved functions of D14 proteins in monocots and dicots.