RESEARCH-PGR: Understanding Recombination in Maize

减数分裂重组是指两条双亲染色体，一个来自父亲，另一个来自母亲，交换部分以产生下一代的过程。这一过程在后代中创造了新的遗传变异，从而促进了对新环境的适应，并清除了基因组中有害的突变。因此，减数分裂重组是进化背后的主要力量之一。此外，它还被用作无与伦比的动植物育种工具。与其重要性形成鲜明对比的是，令人惊讶的是，人们对重组的控制机制知之甚少，特别是在植物中。重组的机制在每个主要的真核生物群体中似乎是不同的，而且也高度依赖于基因组的大小和复杂性。重组事件并不均匀地分布在整个基因组中，但主要发生在称为重组“热点”的不同位置。该项目试图了解为什么以及如何使基因组中的特定位置成为玉米中的重组热点。除了对一个重要的生物学过程提供重要的新见解外，产生的信息将对不断寻找增加重组的新方法以更有效地培育作物的育种者有用。在外展和培训方面，该项目将制定一项理科本科生少数民族辅导实习和培训方案，每年为少数民族本科生提供为期10周的研究培训实习机会。本项目的目的是阐明控制重组事件在玉米中分布的机制。这项工作利用了最近成功构建的启动减数分裂重组的高分辨率双链断裂(DSB)图谱和玉米杂交(CoS)的高分辨率图谱。该计划是为了阐明为什么重组发生在基因组的特定位置，并了解这些位置是如何受到遗传和表观遗传因素的影响的。通过寻找与重组热点中新发现的DNA序列基序相互作用的蛋白质，检测DNA和组蛋白甲基化对热点活性的作用，以及研究DSB热点存在与染色质开放之间的联系，将揭示热点识别的分子机制。此外，还将阐明防止异染色质中CoS形成的机制。这项工作将进一步了解重组是如何在植物中受到控制的，以及它如何影响大型和复杂植物基因组的结构。所有项目成果都将向公众开放。该项目产生的数据将通过项目网站(www.rec-hotpots.org)和适当的长期储存库，如MaizeGDB和NCBI的SRA向公众提供。遗传资源将通过玉米遗传合作库存中心提供。

Meiotic recombination is a process in which two parental chromosomes, one from the father and the other one from the mother, exchange parts to give rise to the next generation. This process creates new genetic variation in the progeny, which facilitates adaptation to new environments and purges detrimental mutations from genomes. Thus, meiotic recombination is one of the main forces behind evolution. In addition, it is utilized as an unparalleled instrument of plant and animal breeding. In stark contrast to its importance, surprisingly little is known about mechanisms controlling recombination, particularly in plants. Mechanisms of recombination appear to be different in each major group of eukaryotes and also highly dependent on genome size and complexity. Recombination events are not evenly distributed throughout the genome but predominantly take place at distinct sites called recombination "hotspots". This project seeks to understand why and how specific sites in the genome become recombination hotspots in maize. In addition to contributing significant new insight into an important biological process, the information generated will be useful to breeders who are continuously looking for new ways to increase recombination for more efficient breeding of crop plants. With regard to outreach and training, the project will develop a Science Undergraduate Minority Mentoring Internship and Training (SUMMIT) program which will provide yearly 10-week research training internships for minority undergraduate students. The goal of this project is to illuminate the mechanisms controlling distribution of recombination events in maize. This work capitalizes on the recent success in generating a high-resolution map of double-strand-breaks (DSBs), which initiate meiotic recombination, and a high-resolution map of crossover (COs) in maize. The plan is to elucidate why recombination takes place in specific sites in the genome and understand how the locations of these sites are affected by genetic and epigenetic factors. The molecular mechanisms of hotspot recognition will be unraveled by searching for proteins interacting with the newly discovered DNA sequence motif present at recombination hotspots, examining the role of DNA and histone methylation on hotspot activity, and investigating the link between DSB hotspot presence and chromatin openness. In addition, mechanisms that prevent formation of COs in heterochromatin will be elucidated. This work will further the understanding of how recombination is controlled in plants and how it affects the structure of large and complex plant genomes. All project outcomes will be made accessible to the public. Data generated in this project will be made available to the public through the project website (www.rec-hotspots.org) and through the appropriate long-term repositories such as MaizeGDB and the NCBI's SRA. Genetic resources will be made available through the Maize Genetics Cooperation Stock Center.