Root Meristem Architecture: The Role of the Quiescent Center

在组织切片的基础上，通过细胞谱系分析对根尖进行了研究。从这种分析得出的顶端组织理论导致了这样的观点，即在细胞谱系的中心，就在根帽的近端，存在着“终极首字母”。人们认为，由于持续的有丝分裂活动，最终的原始细胞产生了衍生细胞，形成了根。1956年发现，这些细胞很少在生长中的根中分裂，这引发了对根发育的重新评估。总的来说，这些不活跃的“终极首字母”组成了一个叫做静止中心(QC)的区域。自从它被发现以来，植物生物学家一直试图了解QC细胞的作用，为什么它们是静止的，以及静止是如何以及何时出现的。本提案中概述的工作解决了这些问题。这项建议的目标是使用分子、遗传和生理方法将已知的根的生物化学与决定根的细胞结构的生物物理学联系起来。将特别注意测量生长素、抗坏血酸和抗坏血酸氧化酶之间的水平、分布和相互作用，目的是将这些物质的变化与静止中心的性质联系起来。使用不同的实验方法，这些物质的水平将被操纵，静止的中心和根尖解剖的状态将被调查。这一努力的意义在于提出了一个新的假说来解释和理解静止中心的建立和发育作用，并最终在根中形成模式。

Root apices have been studied through the analysis of cell lineage based on histological sections. Theories of apical organization derived from such analyses led to the view that there existed "ultimate initials" at the focus of the cell lineage, just proximal to the root cap. As a result of continuous mitotic activity, it was believed, the ultimate initials produced derivative cells that formed the root. The discovery in 1956 that these cells rarely divided in a growing root initiated a reassessment of root development. Collectively, these inactive "ultimate initials" comprise a region called the quiescent center (QC). Since its discovery, plant biologists have tried to understand what the QC cells do, why they are quiescent, and how and when quiescence arises. The work outlined in this proposal addresses these questions. The objectives of this proposal are to use molecular, genetic, and physiological approaches to link the known biochemistry of the root to the biophysics which determines the cellular architecture of the root. Specific attention will be directed to measuring the levels, distributions and interactions between auxin, ascorbic acid and ascorbic acid oxidase with the objective of relating changes in these substances to properties of the quiescent center. Using various experimental approaches, levels of these substances will be manipulated and the status of the quiescent center and apical anatomy investigated. The significance of this effort lies in the advancement of a new hypothesis to account for and understand the establishment and developmental role of the quiescent center and ultimately patterning in roots.