TED1 Promotes the Assembly of SCFD3-D14-D53 to Reinforce Strigolactone Signaling in Rice.

Strigolactones (SLs) are a class of terpenoid lactone hormones that repress plant branching, such as tillering in rice. In rice (Oryza sativa L.), SLs promote the assembly of the SCFD3-D14-D53 complex, which triggers the ubiquitination and degradation of the SL signaling repressor D53, thereby activating downstream responses. Here, we identify TED1, a scaffold subunit of the SWR1-like chromatin remodeling complex, as a critical positive regulator of SL signaling that facilitates the assembly of the SCFD3-D14-D53 complex. The ted1 mutants exhibit reduced sensitivity to the SL analogs 5-deoxystrigol (5DS) and rac-GR24, resulting in increased tillers and dwarfism. We demonstrate that TED1 interacts with D53 independently of SLs and with D14 to enhance the interaction between D14 and D53 or D3 in a SL-dependent manner, thereby efficiently promoting the ubiquitination and degradation of D53. Furthermore, we show that beyond its canonical role in chromatin remodeling function, the C-terminal extension of TED1 homologs has evolved a new key function in reinforcing SL signaling, which may represent a key innovation underlying the enhancement of apical dominance in higher plants.