Polycomb Response Elements (PREs) and Polycomb Recruitment in Plants

智力优势：在真核生物中，基因组DNA在细胞核中高度压缩。这种压缩使得基因组DNA的部分不能被转录因子或一般的转录机制所接近。大部分不可接近的DNA由基因贫乏的异染色质组成。富含基因的常染色质的一部分也是不可接近的或沉默的。这种沉默的一个标志是它只在某些条件下发生，例如在某些细胞类型中或在不存在环境提示的情况下。在多细胞真核生物中，常染色质沉默主要由Polycomb阻遏介导。多梳阻遏物不具有固有的序列特异性;相反，它们需要靶向正确的基因组位点。该项目将确定DNA序列基序，指导多梳阻遏物的常染色质基因组区域在拟南芥适当的植物发育和适当的植物胁迫反应。该项目的最终目标是能够预测-基于DNA序列基序的存在-在这种和其他植物物种中Polycomb阻遏物可以被招募到哪些基因组区域，并确定参与招募的序列特异性结合因子。更广泛的影响：该项目将培训下一代科学家进行最先进的研究。本科研究人员，包括代表性不足的少数民族，将进行个人独立的实验室研究，并在新的一学期的实验室模块进行研究。研究将与项目的主要目标有关。在过去，本科生的贡献一直是优秀的，并保证在科学出版物的作者。该项目将在暑期课程中向高中学生教授与染色质介导的基因组可及性调节相关的主题，并在专业发展会议期间向内城高中的生物学教师教授。最后，该项目将培训来自其他实验室和机构的研究人员掌握该领域使用的关键技术。在植物中，Polycomb阻遏调节向生殖发育、花形成和种子发育的过渡以及对非生物胁迫的响应。理解并因此能够操纵这些活动在植物DNA中的某些区域的募集，因此应该允许改善农业性状，如生物量和种子生产以及水分胁迫耐受性。

Intellectual Merit: In eukaryotes, genomic DNA is highly compacted in the nucleus. This compaction renders portions of the genomic DNA inaccessible to transcription factors or the general transcriptional machinery. A large fraction of the inaccessible DNA consists of gene-poor heterochromatin. Portions of the gene-rich euchromatin are also inaccessible or silenced. A hallmark of this silencing is that it occurs only in certain conditions, for example in some cell types or in the absence of an environmental cue. In multicellular eukaryotes, euchromatic silencing is largely mediated by Polycomb repression. Polycomb repressors do not have inherent sequence specificity; instead, they need to be targeted to the correct genomic loci. This project will identify DNA sequence motifs that direct Polycomb repressors to euchromatic genomic regions in Arabidopsis thaliana for proper plant development and proper plant stress responses. The ultimate goal of the project is to be able to predict--based on the presence of the DNA sequence motifs--which genomic regions Polycomb repressors can be recruited to in this, and in other, plant species and to identify the sequence-specific binding factors involved in the recruitment. Broader Impacts: The project will train the next generation of scientists in state-of the art research. Undergraduate researchers, including underrepresented minorities, will conduct individual independent laboratory research and conduct research in new one-semester-long lab modules. The research will be related to the main objectives of the project. In the past, the undergraduate contributions have been excellent and have warranted authorships on scientific publications. The project will teach topics related to chromatin-mediated regulation of genome accessibility to high-school students in a summer course and to Biology teachers of inner city high schools during professional development sessions. Finally, the project will train researchers from other labs and institutions in critical techniques used in this field. In plants, Polycomb repression regulates the transition to reproductive development, flower formation and seed development as well as response to abiotic stress. Understanding and consequently being able to manipulate the recruitment of these activities to certain regions in the plant DNA should thus allow improvement of agricultural traits such as biomass and seed production as well as water stress tolerance.