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.
生物鐘調(diào)節(jié)動植物的生長與發(fā)育，但其對作物生產(chǎn)的調(diào)控作用卻知之甚少。稻谷產(chǎn)量在很大程度上取決于分蘗，分蘗是由生理和遺傳因素介導(dǎo)的。本文我們報道了一個調(diào)控環(huán)，包括生物鐘、糖和獨腳金內(nèi)酯（SL）通路，調(diào)控水稻分蘗芽和穗的發(fā)育。水稻生物鐘相關(guān)基因OsCCA1正調(diào)控OsTB1(FC1)、矮稈基因D14和理想株型基因IPA1(OsSPL14)的表達(dá)，以抑制分蘗芽的生長。下調(diào)和過表達(dá)OsCCA1分別增加和減少分蘗數(shù)，而操縱響應(yīng)調(diào)節(jié)因子OsPPR1的表達(dá)則會產(chǎn)生相反的效果。OsCCA1還調(diào)節(jié)IPA1的表達(dá)以調(diào)節(jié)穗和籽粒的發(fā)育。利用雙突變體和突變體中過表達(dá)進行遺傳分析表明，OsTB1、D14和IPA1作用于OsCCA1的下游。糖抑制OsCCA1在根和分蘗芽中的表達(dá)，促進分蘗芽的生長。生物鐘整合了糖反應(yīng)和SL途徑來調(diào)節(jié)分蘗和穗的發(fā)育，為改善水稻和其他谷類作物的株型和產(chǎn)量提供了見解。