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。植物作为固着生物，必须不断地防御环境胁迫，而最佳的胁迫反应对作物的生存、繁殖和产量至关重要。应激反应需要对基因表达进行重新编程。此外，基因表达的变化需要是快速和可逆的。本项目将研究重要的Polycomb基因沉默机制如何促进植物对水分胁迫的反应，以及一类非表达的RNA分子的快速合成是否将Polycomb沉默机制引导到需要沉默的适当基因。该项目将为如何增强植物对干旱的反应提供洞察，并将为本科生和高中生提供真实的研究经验。本科生将在实验室课程中参与实验研究，并使用最先进的实验方法在研究实验室进行实验研究。学生们将设计实验，执行程序，并学习如何交流科学。形成性和终结性评估将有助于提高实验课程的效率。相关的高中实验室练习将被开发，皮瓦格纳将在夏季研究学院期间向高中生就这一项目进行讲座和研讨会。近年来，很明显，大多数基因组被转录为非编码转录本，其作用尚不清楚。RNA丰度的变化速度快于蛋白质丰度，这使得lncRNAs非常适合于将染色质调节复合体定向到基因组中的新位置，以响应环境提示。该项目将使用四种互补的方法识别在水分胁迫感应时将多梳复合体招募到新位点的IncRNAs。首先，多梳复合体被迅速招募到的区域以及在水分胁迫感应时被沉默的区域将通过基因组方法来确定。其次，将通过生化和高通量测序相结合的方法鉴定与多梳复合体响应逆境的特异性相关的lncRNAs。第三，通过高通量测序，将鉴定核蛋白结合的lncRNA，其丰度在胁迫条件下增加。最后，将使用反向遗传方法测试在植物胁迫反应和多梳重新招募中的生物学作用，这些多梳相关的lnRNAs在胁迫感应后增加。这项研究的结果将极大地提高对多聚梳招募、lncRNA功能和水分胁迫反应过程中转录重编程的理解。这一结果最终将使我们能够调节染色质调节复合体的招募，以增强植物的可取性状，如对干旱和其他胁迫的耐受性。该项目由分子和细胞生物科学部门的遗传机制计划资助。

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.