Strigolactone
(SL) is a novel plant hormone that regulates important growth and developmental
processes such as plant branching. In rice, the SL receptor D14 perceives SL
signals, binds with the F-box protein D3, and recruits the transcriptional
repressor D53, inducing the ubiquitination and degradation of D53, thereby
triggering signal transduction and inhibiting tillering. A recent study
discovered that nitrogen limitation induces SL biosynthesis in rice to activate
the receptor D14, triggering SL signal transduction. Concurrently, nitrogen
limitation also induces phosphorylation of the N-terminal disordered region
(NTD) of D14, reducing the ubiquitination and degradation of receptor D14,
thereby further enhancing SL perception. Through these two synergistic
mechanisms, nitrogen limitation stimulates SL signal transduction, strongly
inhibiting tillering and enabling rice to adapt to low nitrogen stress
conditions. The study also found that the D14-D3 interaction induced by SL
promotes the ubiquitination and degradation of D14, thereby mediating the
termination of SL signal perception. These significant findings elucidate the
mechanisms of activation and termination of SL perception in rice, revealing
the crucial regulatory role of SL signals in controlling rice tillering under
low nitrogen stress. This would provide key insights into plant adaptation to
nutrient scarcity and guide the precise improvement of crop architecture and
molecular breeding of rice for reduced fertilizer use and increased yield.