Strigolactone promotes cytokinin degradation through transcriptional activation ofCYTOKININ OXIDASE/DEHYDROGENASE 9in rice

Significance Strigolactone plays a vital role in plant growth and development, but its response genes remain to be identified. In this study, we found that cytokinin content is markedly increased in the strigolactone signaling mutant d53 , and that OsCKX9 , which encodes a cytokinin oxidase to catalyze the degradation of cytokinin, functions as a primary strigolactone-responsive gene to regulate rice tillering, plant height, and panicle size, likely via a secondary response gene, OsRR5 , which encodes a cytokinin-inducible rice type-A response regulator, demonstrating that strigolactone regulates rice shoot architecture through enhanced cytokinin catabolism by modulating OsCKX9 expression.