Discovery of Novel Cis-Elements and Transcription Factors Controlling the Plant Defense Transcriptome

控制植物防御转录组的新型顺式元件和转录因子的发现

• 批准号: 0449439
• 负责人: Thomas Eulgem
• 金额: $ 33万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0449439&HistoricalAwards=false
• 关键词: Discovery; Novel; Cis; Elements; Transcription

Plant diseases are the cause for dramatic losses in crop production. To defend themselves against microbial attack, plants have evolved an effective defense system that is inducible upon pathogen recognition. Key steps of plant defenses are coordinated activity changes of large numbers of genes. Such transcriptional re-programming alters the rate of transcription, the synthesis of mRNA copies of these genes. However, details of regulatory processes controlling these defense genes are largely unknown. Previous studies mainly focused on the regulation of individual defense genes. The recently established micro-array technology allows parallel monitoring of mRNA levels of large numbers of genes. Using this technology several groups of genes showing highly coordinated up-regulation in response to pathogen recognition were identified. Genes of each group are likely controlled by common regulatory mechanisms. Typically expression levels of genes are regulated by transcription factors, proteins that interact with short sequences (cis-elements) localized in the respective gene's promoter (DNA sequences upstream of its coding region).The main goal of this project is to systematically identify defense-related cis-elements and their cognate transcription factors by functional genomics in Arabidopsis thaliana. Using microarrays several groups of genes showing highly coordinated responses to pathogen recognition were identified. Sequence motifs found to be strongly conserved in their promoters are likely to constitute cis-elements responsible for their coordinated expression. Such conserved motifs will be tested to determine if they interact with nuclear protein factors and if they can activate reporter genes upon pathogen recognition. Functional cis-elements identified by these experiments will be used to identify their cognate transcription factors by DNA-interactor screening methods, such as the yeast one-hybrid system. The roles of such transcription factors in plant immune responses will be examined by mutational analyses, gene silencing and over-expression. The model Arabidopsis provides all tools required for such a systematic approach, such as a fully sequenced genome, microarrays covering the whole genome and large collections of mutants with insertion mutations in nearly all of its genes. The proposed approach is unbiased and likely to lead to the discovery of novel types of cis-elements and transcription factors. Mechanisms controlling defense genes in Arabidopsis uncovered in this study are likely to apply to other plant species and will facilitate designing new strategies to improve disease resistance in crops. An important component of the proposed project is strong involvement of undergrad students, mainly from minority groups. UC-Riverside is a "Minority Postsecondary Institute" with 30 % minority students in its total enrolled student population. The project will be linked to the ongoing NSF-REU Plant Cell Biology program within the Center for Plant Cell Biology at UC-Riverside. In addition, the proposed project will provide a platform for training of postdoctoral scholars and graduate students in plant molecular biology, plant pathology and functional genomics.

植物病害是造成农作物生产严重损失的原因。为了防御微生物的攻击，植物进化出了一种有效的防御系统，该系统可在病原体识别后诱导。植物防御的关键步骤是大量基因的协调活性变化。这种转录重编程改变了转录速率以及这些基因的 mRNA 拷贝的合成。然而，控制这些防御基因的调控过程的细节在很大程度上尚不清楚。以往的研究主要集中在个体防御基因的调控上。最近建立的微阵列技术可以并行监测大量基因的 mRNA 水平。利用这项技术，鉴定出了几组在病原体识别反应中表现出高度协调上调的基因。每组的基因可能都受到共同的调控机制的控制。通常，基因的表达水平受到转录因子的调节，转录因子是与位于各自基因启动子（其编码区上游的 DNA 序列）中的短序列（顺式元件）相互作用的蛋白质。该项目的主要目标是通过拟南芥的功能基因组学系统地鉴定与防御相关的顺式元件及其同源转录因子。使用微阵列，鉴定了几组对病原体识别表现出高度协调反应的基因。发现在其启动子中高度保守的序列基序可能构成负责其协调表达的顺式元件。将测试这些保守基序，以确定它们是否与核蛋白因子相互作用，以及它们是否可以在病原体识别后激活报告基因。这些实验鉴定出的功能性顺式元件将用于通过DNA相互作用子筛选方法（例如酵母单杂交系统）来鉴定其同源转录因子。这些转录因子在植物免疫反应中的作用将通过突变分析、基因沉默和过度表达来检查。拟南芥模型提供了这种系统方法所需的所有工具，例如完全测序的基因组、覆盖整个基因组的微阵列以及几乎所有基因中都有插入突变的突变体的大量集合。 所提出的方法是公正的，并且可能导致新型顺式元件和转录因子的发现。这项研究发现的拟南芥防御基因控制机制可能适用于其他植物物种，并将有助于设计新策略来提高作物的抗病性。拟议项目的一个重要组成部分是本科生（主要来自少数群体）的大力参与。加州大学河滨分校是一所“少数族裔高等教育学院”，少数族裔学生占其注册学生总数的 30%。该项目将与加州大学河滨分校植物细胞生物学中心正在进行的 NSF-REU 植物细胞生物学项目相关联。此外，该项目将为植物分子生物学、植物病理学和功能基因组学领域的博士后学者和研究生提供培养平台。