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

Nitrogen (N) is an essential macronutrient for food crops. Plants respond to low N (LN) stress by 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 allelic variant of the biosynthetic gene D17 was shown to function in this pathway, confirming SL involvement in low-nitrogen-mediated inhibition of rice crown root formation. Mutations in D17 and D53 (an SL signaling 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 the D53-SPL14/17-WOX11 module modulates CR development adaptations to changes in N availability in rice.