Analysis of Cytokinin Signaling in Arabidopsis

描述（由申请人提供）：细胞分裂素是一组植物激素 它们是强大的有丝分裂原， 流程.对细胞分裂素作用的分子机制的理解 有助于更好地了解人类细胞增殖的调节 细胞关于细胞分裂素信号转导，几乎没有明确的说法。 高等植物我们建议对这一问题采取综合办法， 结合分子、遗传和生物化学方法来阐明 与细胞分裂素作用有关的元素。该提案的主要目的是 从我们分离的两个细胞分裂素初级应答基因，IBC6和IBC7， 它属于一个更大的拟南芥基因家族， 信号元素。我们将利用细胞分裂素特异性诱导GFP 在IBC6启动子-GFP转基因系中的荧光，以鉴定 细胞分裂素作用突变体，通过鉴定不适当地表现出 GFP表达。初步筛选表明，这种方法将是 这些突变体应该有助于剖析细胞分裂素反应 通路IBC6和IBC7的快速诱导，加上它们与IBC7的相似性， 细菌信号元件，表明这些基因可能参与 细胞分裂素信号我们将测试这个假设和其他可能的功能 通过确定ARR基因表达改变的影响， 基因破坏和受调节的过表达，对植物发育和 细胞分裂素反应我们还将鉴定和表征蛋白质， 与IBC6相互作用，作为识别潜在下游靶点的手段， 上游活化剂。我们建议确定顺式作用的DNA序列 负责IBC6的细胞分裂素反应，作为开始 阐明细胞分裂素调节基因表达的机制。一旦 我们将使用这个元件来鉴定其他潜在的细胞分裂素 反应基因，并确定DNA结合蛋白负责 这个元素的功能。最后，我们将使用Affyssin基因芯片， 在拟南芥中鉴定新细胞分裂素调控基因。

DESCRIPTION (provided by applicant): Cytokinins are a group of plant hormones that are powerful mitogens and which play a role in many plant developmental processes. An understanding of the molecular mechanisms by which cytokinins act could help to better understand the regulation of cell proliferation in human cells. Almost nothing definitive is known with regard to cytokinin signaling in higher plants. We propose to utilize an integrative approach to this problem, combining molecular, genetic and biochemical approaches to elucidate the elements involved in cytokinin action. The main thrusts of this proposal derive from our isolation of two cytokinin primary response genes, IBC6 and IBC7, which belong to a larger Arabidopsis gene family that is similar to bacterial signaling elements. We will exploit the cytokinin-specific induction of GFP fluorescence in an IBC6 promoter-GFP transgenic line to identify cytokinin-action mutants by identifying seedlings that inappropriately exhibit GFP expression. Preliminary screens indicate that this approach will be successful and that these mutants should help to dissect the cytokinin response pathway. The rapid induction of IBC6 and IBC7, coupled with their similarity to bacterial signaling elements, suggests that these genes may be involved in cytokinin signaling. We will test this hypothesis and other possible functions of this gene family by determining the effect of altered ARR gene expression, both gene disruption and regulated overexpression, on plant development and cytokinin responsiveness. We will also identify and characterize proteins that interact with IBC6 as a means of identifying potential downstream targets and upstream activators. We propose to identify the cis-acting DNA sequences responsible for the cytokinin-response of IBC6 as a means of starting to unravel the mechanisms by which cytokinins regulate gene expression. Once identified, we will use this element to identify additional potential cytokinin response genes and to identify DNA binding proteins responsible for the function of this element. Finally, we will use Affymetrix gene chips to identify novel cytokinin-regulated genes in Arabidopsis.