Repression Mediated Embryonic Paterning in Arabidopsis

植物开始它们的生命时，有一个非常基本的身体计划，由顶部的茎和底部的根组成。这些结构在胚胎中形成，茎和根的正常发育在很大程度上受一种名为生长素的植物激素的控制。生长素的合成和运输贯穿整个胚胎，因此每个细胞都必须决定是否对它的存在做出反应。这个项目试图揭示细胞用来抑制对生长素的反应的机制，以及当这一过程被破坏时所产生的基因表达和发育变化。由于生长素被用来在植物整个生命周期中形成器官模式，这些研究将广泛适用于植物发育，并将适用于商业上可获得的作物的生长和模式。通过这项工作创建的试剂也将用于Mildred E.Mathias植物园面向普通公众的推广项目以及加州大学洛杉矶分校的本科生课堂。该项目旨在了解拟南芥胚胎模式形成过程中两类转录因子--AUX/IAA和生长素反应因子之间的关系。具体地说，将探索三个AUX/IAA(AUX/IAA8，9，31)和三个ARF(ARF1，2，9)与共抑制物无上装(TPL)共同抑制基因表达的作用。AUX/IAA8和ARF2的全基因组靶标将在胚胎发育过程中使用染色质免疫沉淀和深度测序来确定。然后将这些靶标与TPL的已知靶标进行比较，以定义一个共享的转录网络。AUX/iaa8和arf2突变背景中的RNA-seq将用于将基因表达变化与基因组结合相关联。这项研究还将记录所有六个基因的蛋白质和mRNA积累模式，并将使用表征良好的荧光记者和原位杂交对一个六重突变进行表征。最后，将探索在ARF2中发现的B3抑制基序的生物学功能，并将使用植物内抑制试验在细胞水平上确定ARF2的转录活性。综上所述，这些实验将为该领域提供迄今为止最完整的AUX/IAA和ARF蛋白特征之一。由于这些蛋白质在整个发育过程中都被使用，而且几乎在所有植物中都能找到，所以这一结果应该适用于许多关于植物激素如何调节发育的研究。

Plants begin their life with a very basic body plan consisting of a shoot at the top and a root at the bottom. These structures form in the embryo, and proper development of the shoot and root is controlled in large part by a plant hormone called auxin. Auxin is synthesized and transported throughout the embryo and therefore each cell must make a decision whether to respond or not respond to its presence. This project seeks to uncover the mechanisms used by cells to dampen the response to auxin, and the resulting gene expression and developmental changes that occur when this process is disrupted. As auxin is used to pattern organs throughout the life of the plant, these studies will be broadly applicable to plant development and will apply to the growth and patterning of commercially available crop plants. Reagents created from this work will also be used during outreach programs for the general public at the Mildred E. Mathias Botanical Garden as well as in undergraduate classrooms at the University of California Los Angeles.This project seeks to understand the relationship between two classes of transcription factors, the AUX/IAA and AUXIN RESPONSE FACTORS, during Arabidopsis embryo patterning. Specifically, the action of three AUX/IAAs (AUX/IAA8,9,31) and three ARFs (ARF1,2,9) that work with the co-repressor TOPLESS (TPL) to repress gene expression will be explored. Genome wide targets of AUX/IAA8 and ARF2 will be determined during embryogenesis using chromatin immunoprecipitation followed by deep sequencing. These targets will then be compared to the known targets of TPL to define a shared transcriptional network. RNA-seq in both aux/iaa8 and arf2 mutant backgrounds will be used to correlate gene expression changes with genome binding. The study will also document both the protein and mRNA accumulation patterns of all six of these genes and a characterization of a hextuple mutant will be carried out using well-characterized fluorescent reporters and in situ hybridizations. Finally, the biological function of the B3 repression motif found in ARF2 will be explored and an in planta repression assay will be used to determine the transcriptional activity of ARF2 at a cellular level. Taken together, these experiments will provide the field with one of the most complete characterizations of an AUX/IAA and ARF protein to date. As these proteins are used throughout development and are found in almost all plants, the results should be applicable to many studies on how plant hormones regulate development.