Molecular Genetics of Arabidopsis thaliana

本研究旨在揭示拟南芥花发育的遗传和分子机制。实验分为两个区域。第一个领域是了解花器官识别基因APETALA3和pistilllata的调控和功能。这些基因编码MADS-box DNA结合蛋白，这些蛋白以异源二聚体的形式结合DNA。研究的目的是：找到指定这两个基因初始表达模式的基因，这将通过诱变转基因系来完成，如果MADS-box基因中的任何一个被异位激活，将产生新的表型；并利用差异显示- rt - pcr方法寻找AP3/PI异源二聚体激活或抑制的下游基因。第二个方面是推导出控制茎和花分生组织细胞分裂模式的一般模型。这将通过CLAVATA1， CLAVATA3和WIGGUM基因的分子克隆来完成。在发育的遗传分析中，一个悬而未决的问题是模式形成的问题：诸如植物的花原基或脊椎动物的肢芽等相等细胞的集合是如何在空间上组织起来的，从而发展成不同细胞类型的高度模式集合的？至少涉及两个过程：定形细胞分化，形成细胞类型的最终定形；定形细胞分裂，形成成熟结构的适当大小和形状。花在图案形成的这些方面提供了一个特别好的例子；花通常有固定的器官类型：萼片、花瓣、雄蕊和中心心皮。许多花也有这些器官类型的数量。例如，拟南芥（Arabidopsis thaliana）的花有四个萼片均匀分布在花的周围，四个花瓣在萼片内部并与萼片交替，六个雄蕊和一个由两个心皮组成的复合子房。这里描述的实验将揭示一些细胞机制，通过这些机制，细胞在发育的花中被指示以适当的模式分裂，并被指示分化成适合其位置的细胞类型。如果他们成功的话，这项研究将为器官身份的空间控制以及植物模式形成过程中细胞分裂的空间模式提供新的遗传和分子模型。这些模型将反过来揭示植物发育的遗传原理，并将在未来使植物发育的实验控制成为可能。

9603821 Meyerowitz Technical This research is directed toward revealing the genetic and molecular mechanisms by which Arabidopsis flowers develop. The experiments are divided into two areas. The first area is to understand the regulation and function of the floral organ identity genes APETALA3 and PISTILLATA. The genes code for MADS-box DNA-binding proteins, and the proteins bind DNA as a heterodimer. The research is: to find the genes that specify the initial expression pattern of the two genes, which will be done by mutagenesis of transgenic lines that will give novel phenotypes if either MADS-box gene is ectopically activated; and to find the downstream genes activated or repressed by the AP3/PI heterodimer by use of differential display-RT-PCR methods. The second area is to derive a general model for the control of pattern of cell division in shoot and floral meristems. This will be done by the molecular cloning of the CLAVATA1, CLAVATA3 and WIGGUM genes. Non-technical An unanswered question in the genetic analysis of development is that of pattern formation: How does a collection of equivalent cells such as a plant flower primordium or a vertebrate limb bud become spatially organized, so that it develops into a highly patterned collection of different cell types? At least two processes are involved: patterned cellular differentiation, to give the final pattern of cell types, and patterned cell division, to give the appropriate size and shape to the mature structure. Flowers provide a particularly good example of these aspects of pattern formation; flowers usually have a stereotyped pattern of organ types: sepals, petals, stamens, and central carpels. Many flowers also have defined numbers of each of these organ types. The flower of Arabidopsis thaliana plants, for example, has four sepals spaced evenly around the floral periphery, four petals interior to and alternate with the sepals, six stamens, and a compound ovary of two carpels. The experiments described here will reveal some of the cellular mechanisms by which cells are directed to divide in appropriate patterns in developing flowers, and by which they are instructed to differentiate into appropriate cell types for their positions. If they succeed, the research will result in new genetic and molecular models for the spatial control of organ identity, and for the spatial patterning of cell divisions in plant pattern formation. These models will, in turn, reveal the genetic principles of plant development, and will, in the future, enable experimental control of plant development.