Circadian clocks regulate growth and development in plants and animals, but the role of circadian regulation in crop production is poorly understood. Rice (Oryza sativa) grain yield is largely determined by tillering, which is mediated by physiological and genetic factors. Here we report a regulatory loop that involves the circadian clock, sugar, and strigolactone (SL) pathway to regulate rice tiller-bud and panicle development. Rice CIRCADIAN CLOCK ASSOCIATED1 (OsCCA1) positively regulates expression of TEOSINTE BRANCHED1 (OsTB1, also known as FC1), DWARF14 (D14), and IDEAL PLANT ARCHITECTURE1 (IPA1, also known as OsSPL14) to repress tiller-bud outgrowth. Downregulating and overexpressing OsCCA1 increases and reduces tiller numbers, respectively, whereas manipulating PSEUDORESPONSE REGULATOR1 (OsPPR1) expression results in the opposite effects. OsCCA1 also regulates IPA1 expression to mediate panicle and grain development. Genetic analyses using double mutants and overexpression in the mutants show that OsTB1, D14, and IPA1 act downstream of OsCCA1. Sugars repress OsCCA1 expression in roots and tiller buds to promote tiller-bud outgrowth. The circadian clock integrates sugar responses and the SL pathway to regulate tiller and panicle development, providing insights into improving plant architecture and yield in rice and other cereal crops.

昼夜节律钟调节动植物的生长和发育，但人们对昼夜节律调节在作物生产中的作用知之甚少。水稻（ Oryza sativa ）的产量很大程度上取决于分蘖，而分蘖是由生理和遗传因素介导的。在这里，我们报告了一个涉及生物钟、糖和独脚金内酯（SL）途径的调节循环，以调节水稻分蘖芽和穗的发育。水稻CIRCADIAN CLOCK ASSOCIATED1 ( OsCCA1 ) 正向调节TEOSINTE BRANCHED1 ( OsTB1 ，也称为FC1 )、 DWARF14 ( D14 ) 和IDEAL PLANT ARCHITECTURE1 ( IPA1 ，也称为OsSPL14 ) 的表达，以抑制分蘖芽生长。下调和过表达OsCCA1分别会增加和减少分蘖数量，而操纵PSEUDORESPONSE REGULATOR1 ( OsPPR1 ) 表达会产生相反的效果。 OsCCA1还调节IPA1表达以介导穗和籽粒发育。使用双突变体和突变体中的过度表达进行的遗传分析表明， OsTB1 、 D14和IPA1在OsCCA1下游发挥作用。糖抑制根和分蘖芽中OsCCA1 的表达，促进分蘖芽生长。生物钟整合了糖反应和 SL 途径来调节分蘖和穗部发育，为改善水稻和其他谷类作物的植物结构和产量提供了见解。