Cis and Trans Determinants of Polycomb Recruitment in Plants

当我们面临人口增长和气候变化的双重挑战时，了解植物如何在水分胁迫（干旱）中生存是很重要的。植物作为无根生物，必须不断地保护自己免受环境胁迫，而最佳的应激反应对生存、繁殖和作物产量至关重要。应激反应需要基因表达的重编程。此外，基因表达的变化需要快速和可逆。该项目将研究Polycomb基因沉默机制如何促进植物对水分胁迫的反应，以及一类非表达RNA分子的快速合成是否指导Polycomb沉默机制对合适的基因进行沉默。该项目将深入了解如何提高植物对干旱的反应，并将为本科生和高中生提供真实的研究经验。本科生将在实验课程和研究实验室中使用最先进的实验方法参与实验研究。学生将设计实验，实施程序，并学会科学交流。形成性和总结性评估将有助于提高实验课程的效果。相关的高中实验练习将被开发，PI Wagner将在暑期研究学院为高中生提供关于这个项目的讲座和研讨会。近年来，很明显，大部分基因组转录为非编码转录本，其作用知之甚少。RNA丰度比蛋白质丰度变化更快，这使得lncrna非常适合根据环境信号将染色质调控复合物直接定位到基因组中的新位点。本项目将使用四种互补的方法，识别在水分胁迫感应中招募Polycomb复合物到新位点的lncrna。首先，Polycomb复合体被快速招募的区域和在水胁迫感知中沉默的区域将通过基因组方法来定义。其次，将通过生化和高通量测序相结合的方法鉴定与Polycomb复合物特异性相关的lncrna。第三，通过高通量测序，鉴定出在胁迫条件下丰度增加的核蛋白结合lncRNA。最后，Polycomb相关的lnRNAs在逆境感应时丰度增加，将使用反向遗传方法测试其在植物逆境响应和Polycomb招募中的生物学作用。该研究结果将有助于进一步了解水胁迫反应过程中Polycomb募集、lncRNA功能和转录重编程。这些结果最终将使我们能够调节染色质调控复合体的招募，以增强植物的理想性状，如耐旱和其他胁迫。本项目由分子和细胞生物科学部遗传机制项目资助。

As we face the twin challenges of increased population growth and climate change it is important to understand how plants can survive water stress (drought). Plants as sessile organisms have to continuously defend themselves against environmental stresses and optimal stress responses are critical for survival, reproduction and crop yield. Stress responses require reprogramming of gene expression. Additionally, gene expression changes need to be rapid and reversible. This project will investigate how the essential Polycomb gene silencing mechanism contributes to plant water stress response and whether rapid synthesis of a class of non-expressed RNA molecules directs the Polycomb silencing machinery to the appropriate genes to be silenced. The project will provide insight into how plant drought responses can be enhanced and will provide authentic research experiences for undergraduate and high school students. Undergraduate students will participate in experimental research in laboratory courses and in the research laboratory using state-of-the-art experimental approaches. Students will design experiments, implement procedures and learn to communicate about science. Formative and summative assessments will help improve the efficacy of the laboratory course. Related high school laboratory exercises will be developed and PI Wagner will give lectures and workshops to high school students about this project during summer research academies.In recent years it has become apparent that the majority of the genome is transcribed as noncoding transcripts, the roles of which are poorly understood. RNA abundance can change more rapidly than protein abundance, making lncRNAs ideally suited to direct chromatin regulatory complexes to new sites in the genome in response to environmental cues. This project will identify lncRNAs that recruit Polycomb complexes to new loci upon water stress sensing using four complementary approaches. First, regions to which Polycomb complexes are rapidly recruited and that are silenced upon water stress sensing will be defined by genomic approaches. Second, lncRNAs that specifically associate with the Polycomb complexes in response to the stress will be identified by combined biochemical and high-throughput sequencing approaches. Third, nuclear protein-bound lncRNA will be identified whose abundance increases under stress conditions by high-throughput sequencing. Finally, Polycomb-associated lnRNAs that increase in abundance upon stress sensing will be tested for biological roles in plant stress response and in Polycomb recruitment using reverse genetic approaches. Findings from this study will significantly enhance understanding of Polycomb recruitment, lncRNA function and transcriptional reprogramming during water stress response. The results ultimately will enable us to modulate chromatin regulatory complex recruitment to enhance desirable traits in plants such as tolerance to drought and other stresses.This project is funded by the Genetic Mechanisms Program in the Division of Molecular and Cellular Biosciences.