Strigolactones affect the translocation of nitrogen in rice

Strigolactones (SLs) are involved in the nutrient-dependent control of plant root and shoot architecture. The total sufficient uptake of nitrogen (N), and also its appropriate distribution, is essential for the normal growth and development of plants; however, the effect of SLs on N translocation in plants remains unknown. Here, the SL-signaling mutant dwarf 3 (d3), the biosynthesis mutant dwarf 10 (d10), and wild-type (WT) rice (Oryza sativa ssp. Japonica cv. Nipponbare) were used to investigate the relationship between N nutrition and the regulatory role of SLs. Relative to WT, the d10 mutant had a higher N concentration in older leaves but a lower N concentration in younger leaves, while the d3 mutant showed a considerably lower N concentration, especially in its younger leaves under normal N levels. By contrast, both d3 and d10 mutants contained higher N in their leaves under N-deficient conditions. The ¹⁵N uptake and distribution analysis revealed that the significantly different N concentrations among the d3, d10, and WT plants only occurred in their leaves, not in their roots. Moreover, when provided with an external supply of GR24, the synthetic SLs altered the leaf N distribution of the d10 mutant but not those of the d3 mutant and WT. Together, these results suggested that the effect of SLs on plant growth and development may be linked to N translocation to different shoot tissues.