Establishment of Embryonic Stem Cell Niches in Maize

玉米胚胎干细胞生态位的建立

• 批准号: 467810733
• 负责人: Professor Dr. Thomas Dresselhaus
• 金额: --
• 依托单位: Lehrstuhl für Zellbiologie und Pflanzenbiochemie
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/467810733?language=en
• 关键词: Establishment; Embryonic; Stem; Cell; Niches

Specification of stem cell precursor cells leading to the establishment of embryonic meristems occurs already at the radial 16-celled dermatogen stage in the model plant Arabidopsis. Gene regulatory networks required for cell specification include the auxin-induced MONOPTEROS (MP)-BODENLOS (BDL) module consisting of the ARF transcription factor MP and its repressor BDL as well as WUSCHEL (WUS) and WUS-related homeobox (WOX) transcription factors. Compared with Arabidopsis, almost nothing is known about how meristems are established and organized during embryogenesis in cereals. Cell fate decisions during embryogenesis in Arabidopsis are strictly coupled to stereotypic cell division patterns, while cell division planes in cereal embryogenesis appear chaotic and random. Thus, how are meristem precursor and stem cells specified in cereals? The few descriptive reports studying hormone transport and responses as well as gene expression pattern of WUS/WOX homologs by in situ hybridization suggest that these processes are not conserved between maize and Arabidopsis. Meristem initiation occurs much later in maize, after symmetry breaking at the transition stage when the embryo consists already of hundreds of cells. Moreover, our preliminary data predict that auxin generated in the endosperm can trigger symmetry breaking, that this cell specification might initially be prevented by the embryo surrounding region (ESR), a specialized endosperm structure lacking in Arabidopsis, that ARF-IAA modules different from MP-BDL regulate embryonic meristem establishment, and that this involves also cereal-specific molecular players. Thus, to understand meristem establishment in cereals, this ambitious project aims (i) to identify and study the role of auxin-regulated ARF-IAA modules expressed at the transition stage of maize embryos, (ii) to elucidate the role of the ESR in early embryo patterning, (iii) to understand the role of the ZmWUS1/ZmWOX5 gene regulatory network for the establishment of embryonic stem cell niches and (iv) to identify the function and targets of the cereal-specific EAL1 signal peptide that is secreted asymmetrically at the apical embryo domain at the transition stage.

在模式植物拟南芥中，导致胚胎分生组织建立的干细胞前体细胞的特化已经发生在放射状16细胞皮肤原阶段。细胞特化所需的基因调控网络包括由ARF转录因子MP及其阻遏物BDL以及WUSCHEL（WUS）和WUS相关同源框（WOX）转录因子组成的生长素诱导的MONOPTEROS（MP）-BODENLOS（BDL）模块。与拟南芥相比，几乎没有人知道分生组织是如何建立和组织在胚胎发生过程中在谷物。拟南芥胚胎发生过程中的细胞命运决定与刻板的细胞分裂模式密切相关，而谷类胚胎发生中的细胞分裂平面则表现为混乱和随机。因此，在谷物中，分生组织前体细胞和干细胞是如何被指定的？通过原位杂交研究激素转运和响应以及WUS/WOX同源物的基因表达模式的少数描述性报告表明，这些过程在玉米和拟南芥之间不保守。在玉米中，分生组织的发生要晚得多，在胚已经由数百个细胞组成的过渡阶段对称性破缺之后。此外，我们的初步数据预测，在胚乳中产生的生长素可以触发对称性破缺，这种细胞规格可能最初被阻止的胚胎周围区域（ESR），一个专门的胚乳结构缺乏拟南芥，ARF-IAA模块不同MP-BDL调节胚胎分生组织的建立，这也涉及到谷物特定的分子球员。因此，为了了解谷物分生组织的建立，这个雄心勃勃的项目旨在（i）鉴定和研究在玉米胚过渡阶段表达的生长素调节的ARF-IAA模块的作用，（ii）阐明ESR在早期胚图案形成中的作用，（iii）了解ZmWUS 1/ZmWOX 5基因调控网络在建立胚胎干细胞小生境中的作用，以及（iv）鉴定在过渡阶段在顶端胚结构域不对称分泌的谷物特异性EAL 1信号肽的功能和靶点。