The SvFUL2 transcription factor is required for inflorescence determinacy and timely flowering in Setaria viridis

背景回顾：Inflorescence architecture in cereal crops directly impacts yield potential through regulation of seed number and harvesting ability. Extensive architectural diversity found in inflorescences of grass species is due to spatial and temporal activity and determinacy of meristems, which control the number and arrangement of branches and flowers, and underlie plasticity. 

提出问题：Timing of the floral transition is also intimately associated with inflorescence development and architecture, yet little is known about the intersecting pathways and how they are rewired during development. 

主要发现：Here, we show that a single mutation in a gene encoding an AP1/FUL-like MADS-box transcription factor significantly delays flowering time and disrupts multiple levels of meristem determinacy in panicles of the C4 model panicoid grass, Setaria viridis. 

结果1-先前报道：Previous reports of AP1/FUL-like genes in cereals have revealed extensive functional redundancy, and in panicoid grasses, no associated inflorescence phenotypes have been described. 

结果2-突变：In S. viridis, perturbation of SvFul2, both through chemical mutagenesis and CRISPR/Cas9-based gene editing, converted a normally determinate inflorescence habit to an indeterminate one, and also repressed determinacy in axillary branch and floral meristems. 

结果3-组学分析：Our analysis of gene networks connected to disruption of SvFul2 identified regulatory hubs at the intersect of floral transition and inflorescence determinacy, providing insights into the optimization of cereal crop architecture.

 摘 要 

谷类作物的花序结构通过种子数量和采收能力直接影响了作物的产量潜力。草本植物的花序存在广泛的结构多样性，这是由于分生组织的时空活性及有限性差异所导致的，这些特性控制了植株分枝和花的数量和排列，并决定了这些表型的可塑性。成花转变的时间与花序发育和结构息息相关，但是这些生物学过程之间的交叉部分及发育过程中调控机制的还不清楚。本文中，作者发现C4模式黍族植物狗尾草（Setaria viridis）中一个AP1/FUL类MADS-box转录因子的功能突变能够显著延迟开花，并且会扰乱狗尾草分生组织的有限性。先前对于谷物AP1/FUL-like基因的研究显示这一类的基因具有广泛的功能冗余，并且在黍族植物中，并未报道过与花序表型相关的功能。在狗尾草中，通过化学诱变或是CRISPR-Cas9介导的基因编辑扰乱SvFul2基因的表达，会导致正常的有限花序转变为无限花序，并且抑制腋枝和花分生组织的有限性。最后，作者对与SvFul2基因表达干扰后的基因网络进行了分析，鉴定了成花转变和花序有限性两个生物学事件相交叉的调控中心，为谷类作物的株型结构优化提供了新的见解。