Molecular Genetics of Cell Differentiation in Arabidopsis

该研究的目的是了解从细胞发育命运的选择到其最终分化表型的阐述的步骤。这个问题正在以拟南芥（Arabidopsis thaliana）叶片上的毛发（毛状体）作为理解细胞分化控制的模型进行研究。这些毛状体是从表皮延伸出来的高度特化的单细胞。虽然在野外，拟南芥的毛状体已被证明对昆虫食草动物提供重要的保护，但毛状体在实验室条件下不是必需的。此外，毛状体位于植物表面，很容易观察到突变表型。毛状体的这两个特征有助于突变体的分离和遗传分析。已经确定了20多种影响毛状体发育和/或形态的基因突变，并且已经克隆了3种影响毛状体发育的基因。在毛状体发育途径中最早起作用的两个基因已被证明是转录因子。这些基因使表皮细胞进行高度特化的分化过程，包括细胞形状的剧烈变化。目前，人们对转录因子如何控制任何生物体中细胞的极化生长等过程知之甚少。该项目的最终目标是将细胞命运决定过程中发生的事件与负责成熟毛细胞表型的细胞机制联系起来。这种联系在所有生物中都知之甚少，对毛状体发育的研究可能会产生对理解植物和动物发育具有广泛意义的结果。

The objective of the research is to understand the steps that lead from the selection of a cell's developmental fate to the elaboration of its ultimate differentiated phenotype. This problem is being studied using hairs (trichomes) on the leaves of the plant Arabidopsis thaliana as a model for understanding the control of cell differentiation. These trichomes are highly specialized single cells that extend out from the epidermis. Although in the field, Arabidopsis trichomes have been shown to provide significant protection from insect herbivores, trichomes are non-essential under laboratory conditions. In addition, trichomes are located on the surface of the plant, and mutant phenotypes are readily observed. These two features of trichomes have facilitated the isolation of mutants and genetic analysis. Mutations in more than twenty different genes have been identified that affect trichome development and/or morphology, and three genes affecting trichome development have been cloned. Two of the earliest-acting genes in the trichome development pathway have turned out to be transcription factors. These genes commit an epidermal cell to a highly specialized differentiation process involving dramatic changes in cell shape. At present, there is little understanding of how transcription factors can control processes such as polarized growth of a cell in any organism. The ultimate goal of this project is to connect events occuring during the cell fate decision and the cellular mechanisms responsible for the mature trichome cell phenotype. This connection is poorly understood in all organisms, and the study of trichome development is likely to produce results with broad implications for understanding development in plants and animals.