Establishment and maintenance of repressive chromatin during development in plants

该项目将研究植物在发育过程中如何通过改变基因在细胞核中的包装方式来控制特定基因的表达。 在植物中，就像在其他真核生物中一样，非常大的基因组通过将基因组DNA缠绕在蛋白质周围以形成称为染色质的紧凑的DNA-蛋白质复合物而被包装到细胞核的小空间中。 非常紧密的染色质可以通过尚未完全理解的机制阻止基因表达。 探讨这些机制是本提案的重点。 一个长期目标是利用研究成果来操纵植物的发育，以增加其农业潜力。该研究将由本科生和研究生共同开展，为本科生提供真实的研究经验，并为研究生提供指导机会。此外，该项目中产生的基因组数据的分析将被纳入一个新的计算基因组学课程，教学生如何使用计算方法分析大型数据集。 在包括模式植物拟南芥在内的真核生物中，核小体染色质中组蛋白H3（H3 K27 me 3）上赖氨酸27的三甲基化与转录抑制有关，但是这种组蛋白修饰是如何被施加、维持和读取的还知之甚少。 命名为PICKLE（PKL）的染色质重塑剂先前已显示促进组织和发育特异性抑制染色质，由H3 K27 me 3的存在定义。 最近的证据表明，PKL可能作为一个前核小体成熟因子，与组蛋白甲基转移酶，第二重塑，和组蛋白H2 A的变体，以控制从H3 K27 me 3富集位点的条件表达。 这种关系将通过结合遗传学，基因组学和生物化学方法来测试，以将染色质介导的基因表达变化与整株发育表型联系起来。 该结果有望揭示H3 K27 me 3稳态在抑制性染色质状态的形成和维持中的作用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will study how plants control expression of specific genes during development by changing how the genes are packaged in the nucleus. In plants, like in other eukaryotic organisms, the very large genome is packaged into the small space of the cell's nucleus by winding the genomic DNA around proteins to form a compacted DNA-protein complex called chromatin. Very tightly compacted chromatin can prevent gene expression by mechanisms that are not fully understood. Exploring these mechanisms is the focus of this proposal. A long-term goal will be to use the research outcomes to manipulate development in plants to increase their agricultural potential. The research will be carried out by undergraduate and graduate students working together, providing an authentic research experience for undergraduate students and mentoring opportunities for the graduate students. In addition, analysis of the genomic data generated in the project will be incorporated into a new computational genomics course to teach students how to analyze large datasets using computational approaches. All of the data generated by the project will be deposited in public databases.In eukaryotes, including the model plant Arabidopsis thaliana, trimethylation of lysine 27 on histone H3 (H3K27me3) in nucleosomal chromatin is associated with transcriptional repression, but how this histone modification is imposed, maintained, and read is poorly understood. The chromatin remodeler named PICKLE (PKL) has been shown previously to promote tissue- and developmental-specific repressive chromatin, defined by the presence of H3K27me3. Recent evidence suggests that PKL may function as a pre-nucleosome maturation factor that acts with a histone methyltransferase, a second remodeler, and a histone H2A variant to control conditional expression from H3K27me3-enriched loci. This relationship will be tested by combining genetic, genomic, and biochemical approaches to relate chromatin-mediated changes in gene expression to whole-plant developmental phenotypes. The results are expected to reveal the role of H3K27me3 homeostasis in formation and maintenance of repressive chromatin states.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.