D53-SPL14/17-WOX11 module modulates rice crown root development adaptations to changes in nitrogen availability

Nitrogen (N) is an essential macronutrient for food crops. Plants respond to low N (LN) stress through altering their root morphology. Strigolactones (SLs) are important modulators of root growth in plants. However, the functions of SLs and their downstream pathway in N-modulated formation of crown roots (CRs) remain unclear. In this study, we found that LN inhibits the occurrence of CRs in rice, with significant differences observed between japonica and indica varieties. A natural variant of D17, a gene involved in SL biosynthesis, was identified as participating in this process, revealing that SL is involved in LN-inhibited CR development in rice. Mutations in D17 and D53 (an SL signalling repressor) caused CR development under N deficiency. Under LN conditions, the perception of SLs by D14 triggered the ubiquitin-proteasome-mediated degradation of D53, thereby releasing SPL14 and SPL17 (SPL14/17) to inhibit CR formation and ultimately resulting in fewer CRs in rice. Additionally, SPL14/17 interacted with WOX11 and repressed its transcriptional activity by attenuating its DNA-binding ability. Moreover, loss of WOX11 function in the spl14 spl17 double mutant suppressed the enhanced CR formation observed under LN conditions, demonstrating that WOX11 acts downstream of SPL14/17 to induce rice CR formation in response to different levels of N supply. Taken together, our findings suggest a novel regulatory pathway in which D53-SPL14/17-WOX11 module modulates CR development adaptations to changes in N availability in rice.