Inflorescence and spikelet meristem establishment and maintenance in barley

花序结构控制着花和种子的生产，主要由分生组织的特性和确定性决定决定。草花序分生组织(IM)产生一种独特的结构，即小穗分生组织(SM)，然后产生花分生组织(FM)、花和种子。在温带谷物大麦中，花序内这些不同分生组织的建立、维持和终止如何在遗传上受到控制还不是很清楚。我们已经鉴定和描述了三种不同的转录因子，它们控制着分生组织的决定性和身份转换，从而控制大麦穗上产生的小穗和花的数量。中位基因(CEN)和中间M/双种子1号(INT-M/DUB1)促进IM的不确定性和小穗分生组织(SM)的确定性，而开花基因T1(FT1)则促进IM和SM的不确定性。这些结果表明，在大麦中，IM和SM的决定是遗传协调的，并且是负相关的。在这里，我们建议使用FT1、cen和int-m/dub1突变体来剖析花序分生组织决定和身份转换的分子网络。具体地说，我们将(I)使用激光捕获显微切割(LCM)和RNA测序(LCM-RNA-SEQ)识别FT1/CEN和INT-M下游转录网络中IM和SM/FM特异性的变化，然后对候选基因进行功能分析；(Ii)使用激素报告线和激素水平变化的测量来破译IM和SM确定性与激素动态平衡和反应之间的联系。最终目标是确定特定控制不同大麦分生组织IM和SM/FM命运的分子网络。通过整合来自联盟合作伙伴的关于玉米、大麦和担子属不同干细胞系统调控的信息，我们将能够就谷物干细胞系统的分子控制及其在不同分生组织和物种之间的差异建立一个共同的框架。

Inflorescence architecture controls flower and hence seed production and is largely defined by meristem identity and determinacy decisions. Grass inflorescence meristems (IM) produce a unique structure, spikelet meristems (SM) that then produce floral meristems (FM), flowers, and seeds. How the establishment, maintenance, and termination of these different meristems within the inflorescence are genetically controlled in the temperate cereal barley is not well understood.We have identified and described three different transcription factors that control meristem determinacy and identity transitions and thereby the number of spikelets and flowers produced on the barley spike. CENTRORADIALIS (CEN) and INTERMEDIUM-M/DOUBLE SEED 1 (INT-M/DUB1) promote IM indeterminacy and spikelet meristem (SM) determinacy, while FLOWERING LOCUS T1 (FT1) promotes IM determinacy and SM indeterminacy. These results suggest that IM and SM determinacy are genetically coordinated and negatively correlated in barley. Here, we propose to use ft1, cen, and int-m/dub1 mutants to dissect the molecular network underlying inflorescence meristem determinacy and identity transitions. Specifically, we will (i) identify IM and SM/FM-specific changes in transcriptional networks downstream of FT1/CEN and INT-M using laser capture microdissection (LCM) and RNA-sequencing (LCM-RNA-seq) followed by functional analyses of candidate genes and (ii) decipher the link between IM and SM determinacy and hormone homeostasis and response using hormone reporter lines and measurements of hormone level changes. The ultimate goal is to identify molecular networks that specifically control the fate of the different barley meristems, IM and SM/FM. By integrating information from the consortium partners on the regulation of different stem cell systems in maize, barley and Brachypodium we will be able to develop a common framework on the molecular control of cereal stem cell systems and their variation between different meristems and species.