Molecular Genetic Studies of Embryo Maturation in Maize

发育中的植物胚胎具有发芽或成熟的能力。Rivin博士正在研究胚胎脱落酸水平、激素敏感性和水关系变化如何调节这两种发育潜能的表达。她的目标是在分子水平上定义玉米胚胎成熟过程中由这些生理信号调节的发育途径，并确定调节其表达的遗传机制。为了解决这个问题，她将遵循一个由三部分组成的项目，包括分子和遗传方法，重点关注那些在成熟阶段未能成功发育的突变体。具体目标如下：1)利用她之前对野生型和胎生突变体成熟期多肽合成的观察，鉴定胚胎成熟特异性mrna的cDNA克隆，作为选择共调控信息集的基础。2)在正常玉米胚胎发生过程中测量成熟mrna的表达，并研究当胎生和缺陷核突变体的发育被遗传破坏时，或通过组织培养中生理因素的操纵，该程序是如何改变的。3)寻找新的转座子标记的胚胎致死性突变体，为胚胎成熟的遗传解剖收集额外的基因位点，并为胚胎发育所需基因的克隆提供手段。在开花植物中，发育中的种子形成形态完整的胚，并最终发芽。胚胎发育分为两个阶段，第二个阶段称为成熟。这个项目旨在了解控制这个成熟过程的因素。

Developing plant embryos have the capacity to germinate or to mature. Dr. Rivin is investigating how embryo abscisic acid level, hormone sensitivity and changing water relations modulate the expression of these two developmental potentials. Her goals are to define, at the molecular level, the developmental pathways that are modulated by these physiological cues during maize embryo maturation, and to identify the genetic mechanisms that regulate their expression. To address this problem she will follow a three part program that involves both molecular and genetic approaches, focussing on mutants that fail to develop successfully through maturation phase. The specific objectives are the following: 1) Identify cDNA clones of mRNAs that are specific to embryo maturation, using her previous observations about the synthesis of maturation phase polypeptides in wild type and viviparous mutants as a basis for selection of co-regulated message sets. 2) Measure the expression of maturation mRNAs during normal maize embryogenesis and examine how this program is altered when development is disrupted genetically in viviparous and defective kernel mutants, or by manipulation of physiological factors in tissue culture. 3) Search for new transposon tagged embryo lethal mutants to collect additional loci for genetic dissection of embryo maturation, and to provide a means of cloning genes essential to embryo development. %%% In flowering plants the developing seed creates a morphologically complete embryo which goes on eventually to germinate. Embryo development takes place in two stages, the second of which is termed maturation. This project is aimed at an understanding of the factors that control this maturation process.