Cell Fate Acquisition in Maize

首席研究员：Virginia Walbot（斯坦福大学）首席研究员：W. Zacheus Cande（加州大学伯克利分校，二等受奖人）高级研究员：Lisa Harper（加州大学伯克利分校/USDA-ARS）随着复杂生物体的发展，首先建立机体计划，然后是器官的规范，然后是组成组织，最后是功能细胞类型的指定。细胞命运获得的调控发生在许多层面上，反映在细胞内的基因表达和蛋白质含量上，包括对周围组织提供的激素等外部信息的反应。尽管细胞命运对最终功能至关重要，但这一过程在具有多种细胞类型的复杂组织中很难研究，因为这一过程在许多组织中是异步发生的。该项目将利用五种主要细胞类型及其在花药内的同步发育来解剖玉米的细胞命运。基因表达和蛋白质的变化将使细胞与命运不同的相邻细胞区分开来。在花药发育的特定阶段细胞命运获得缺陷的突变体将通过筛选大量先前工作建立的玉米雄性不育突变体来恢复。通过比较正常和突变花药的细胞表达模式，阐明细胞命运获取的正常进程。选择的突变体将被描述细胞学和他们的基因表达模式。最后，定义关键突变阶段的基因将被克隆，以确定正常细胞命运获得所必需的基因产物的性质。项目过程中产生的数据，包括微阵列数据和突变体的细胞学描述，将通过GEO (Gene Expression Omnibus， GEO) （http://www.ncbi.nlm.nih.gov/geo/）和MaizeGDB （http://www.maizegdb.org）提供。生物资源将通过该项目和玉米遗传合作-库存中心（http://maizecoop.cropsci.uiuc.edu）提供。在大多数植物和动物中，减数分裂前细胞缺乏同步性，这阻碍了对这种特殊命运决定所需步骤的深入分析。因此，该项目的新知识和见解将阐明减数分裂细胞和周围体细胞的细胞命运规范步骤，这将对理解复杂的植物和动物发育具有普遍意义。为了让农业专业的本科生熟悉植物遗传学的现代方法，该项目的基因标记部分将在加州理工学院圣路易斯奥比斯波分校进行。项目高级人员将使学生熟悉植物转座子标记的理论，然后训练学生在田间筛选雄性不育突变体，对繁殖突变体进行遗传杂交，对先前鉴定的具有相似表型的突变体进行等位基因测试，解剖花药分析基因表达，准备DNA样本用于克隆新标记的突变等位基因。

PI: Virginia Walbot (Stanford University)CoPI: W. Zacheus Cande (University of California, Berkeley; subawardee)Senior Personnel: Lisa Harper (University of California, Berkeley/USDA-ARS)As complex organisms develop, the body plan is established first, followed by the specification of organs, then their constituent tissues, and finally the functional cell types are designated. The regulation of cell fate acquisition occurs at many levels and is reflected in the gene expression and protein content within the cells and includes responses to external information such as hormones provided by surrounding tissues. Despite the importance of cell fate to final function, this process is difficult to study in complex tissues with many cell types and because the process is occurring asynchronously in many tissues. This project will exploit the five major cell types and their synchronous development within anthers to dissect cell fate in maize. Gene expression and protein changes that distinguish cells from their neighbors with a different fate will be defined. Mutants defective in cell fate acquisition at specific stages of anther development will be recovered by screening large collections of male-sterile mutants of maize established by prior work. The normal progression of cell fate acquisition will be elucidated by comparing cell expression patterns of normal to mutant anthers. Selected mutants will be described cytologically and by their pattern of gene expression. Finally, genes defining key mutant stages will be cloned to determine the nature of the gene product essential for normal cell fate acquisition. Data generated in the course of this project including microarray data and cytological descriptions of mutants will be made available through GEO (Gene Expression Omnibus (GEO) (http://www.ncbi.nlm.nih.gov/geo/) and through MaizeGDB (http://www.maizegdb.org). Biological resources will be available through the project and through the Maize Genetics Cooperation - Stock Center (http://maizecoop.cropsci.uiuc.edu). The lack of synchrony in pre-meiotic cells in most plants and animals has precluded deep analysis of the steps required for this particular fate decision. Consequently, new knowledge and insights from this project will illuminate steps in cell fate specification for the meiotic cells and surrounding somatic cells that will be of general significance in understanding both complex plant and animal development. To acquaint undergraduate students of agriculture focus with modern methods in plant genetics, the gene-tagging component of the project will be conducted at CalPoly-San Luis Obispo. Project senior personnel will acquaint students with the theory of transposon tagging in plants, and then train students to screen for male-sterile mutants in the field, to conduct genetic crosses for propagating mutants, to conduct allelism tests with previously identified mutants conferring similar phenotypes, to dissect anthers for analysis of gene expression, and to prepare DNA samples for the cloning of newly tagged mutant alleles.