Regulation of Shoot Development by the Maize Meristem

爱尔兰9728518 高等植物的茎顶端分生组织在植物的整个生命过程中，最终负责胚后向茎添加新的细胞、组织和器官。在营养体发育期间，分生组织以重复的方式启动叶和茎组织。随着营养体发育的进展，新形成的器官分化的方式可能会发生变化，这一过程称为相变。一旦进入生殖阶段，茎分生组织形成或成为花分生组织，启动可预测的和确定的花器官序列。关于营养枝顶端分生组织的功能，如它如何启动侧生器官，在多大程度上决定这些器官如何分化，以及营养分生组织如何召集成花序或花分生组织，还有很多有待了解。 这里提出的研究的重点是问什么控制发生在茎尖的各种发育过程。实验将使用玉米植株进行，并将利用我们为玉米开发的技术，即茎分生组织培养。我们以前的实验使用分生组织培养表明，无论是从营养到生殖发育的变化和相变的过程是在全局信号的控制下，发生在整个植物。我们提出了一组实验，旨在了解如何在玉米全球信号与分生组织自主活动的协调。以下问题将得到解决：1。不定基因是玉米向开花过渡所需的基因，其表达如何受到培养诱导的茎尖重置的影响？2.当分生组织被迫经历一个延长的营养发育期时，它是如何重组的？3.当一个成年分生组织被分离并形成一个完整的新芽时，所有的阶段特异性表型都被重置了吗？如果重置发生在一个特定的基因（PI印迹），该基因座的甲基化状态是如何受到影响的？4.在突变体背景中，其中少年期延长和繁殖延迟，这是改变（较弱）的叶原基信号的结果？异时突变的表达是依赖于植物的生长阶段，还是依赖于萌发后的自由运行时间？这些问题的答案将增加我们的理解，在拍摄个体发育过程中发生的全球变化和拍摄分生组织，器官发生的网站，在指导这些变化的作用。

Irish 9728518 The shoot apical meristem of higher plants is ultimately responsible for the post-embryonic addition of new cells, tissues, and organs to the shoot through-out the life of the plant. During vegetative development, the meristem initiates leaves and stem tissue in a repetitive manner. As vegetative development progresses, the manner in which newly formed organs differentiate may vary, in a process termed phase change. Once in the reproductive phase, shoot meristems form or become floral meristems, which initiate a predictable and determinate sequence of floral organs. Much remains to be learned about the functioning of the vegetative shoot apical meristem, such as how it initiates lateral organs, to what extent it determines how those organs differentiate, and how the vegetative meristem is convened to an inflorescence or floral meristem. The focus of the research proposed here is to ask to what controls various developmental processes that occur at the shoot apex. The experiments will be conducted using the maize plant, and will take advantage of a technique, shoot meristem culture, that we have developed for maize. Our previous experiments using meristem culture indicated that both the change from vegetative to reproductive development and the process of phase change are under the control of global signaling that occurs throughout the plant. We propose a set of experiments that are aimed at understanding how global signaling in maize is coordinated with meristem-autonomous activities. The following questions will be addressed: 1. How is the expression of indeterminate, a gene required for the transition to flowering in maize, affected by the culture-induced resetting of a shoot apex? 2. How is the meristem reorganized when it is forced to undergo a prolonged period of vegetative development? 3. Are all phase-specific phenotypes reset when an adult meristem is isolated and forms a complete new shoot? If resetting occurs in a specific gene (PI-Blotched), how is the methylation state of that locus affected? 4. In mutant backgrounds in which the juvenile phase is prolonged and reproduction delayed, is this slower ontogeny the result of altered (weaker) signaling from leaf primordia? Is the expression of heterochronic mutations dependent on the phase of the plant, or on a free-running measurement o1' time after germination? The answers to these questions will increase our understanding of the global changes that occur during shoot ontogeny and the role of the shoot meristem, the site of organogenesis, in directing these changes.