Functional Genomics of Maize Centromeres

Pi：R.Kelly Dawe(佐治亚大学雅典分校)共同Pis：James A.Birchler(密苏里大学哥伦比亚分校)和Jiing酱(威斯康星大学麦迪逊分校)所有植物基因组都含有着丝粒，这是确保染色体在细胞分裂过程中正确分离的结构区域。着丝粒是研究的一个挑战，因为它们包含重复的DNA序列和很少的基因。该项目的目标是了解着丝粒中的序列如何与其功能相关，以及着丝粒大小的变化或关键着丝粒结合蛋白(CENH3)的变化如何改变着丝粒的行为。特别是，该项目将研究可能导致杂交后代着丝粒失败和染色体丢失的遗传杂交和突变。着丝粒修饰引起的染色体丢失可导致单倍体植株，这对玉米育种者具有重要价值，因为它们可以迅速加速新自交系的产生。预计产生的信息和技术将直接应用于农业--不仅是玉米，而且是利用单倍体作为育种工具的所有其他作物。在培训和推广方面，该项目将为本科生和研究生以及植物基因组学和生物技术博士后研究员提供研究培训。此外，还将举办一系列培训讲习班，以传播该项目产生的技术和材料。所有项目成果将通过一个专门的项目网站和包括NCBI、MaizeGDB和Gramene在内的长期储存库传播给研究界。该项目的总体目标是了解玉米着丝粒的遗传和表观遗传成分，并揭示着丝粒大小在单亲染色体消除中的作用，从而导致单倍体的形成。其具体目标是：1)使用新的染色体绘制探针和染色体可视化工具来确定共同的着丝粒重复序列是否足以诱导着丝粒功能，这些工具显著提高了检测染色体结构变化的能力；2)使用转入燕麦中的玉米染色体和经历了一轮失活和再激活的B染色体，确定一套染色质标记如何受到着丝粒大小和位置变化的影响；3)通过筛选着丝粒大小已通过操纵基因组大小改变的着丝粒的品系，以及通过使用具有特殊转基因的cen3突变体来测试着丝粒大小差异是否会导致单亲基因组消除；以及4)确定玉米着丝粒在单亲基因组消除的情况下的行为，特别是在单倍体育种计划中经常使用的小麦×玉米和燕麦×玉米杂交中。

PI: R. Kelly Dawe (University of Georgia-Athens) Co-PIs: James A. Birchler (University of Missouri-Columbia) and Jiming Jiang (University of Wisconsin-Madison) All plant genomes contain centromeres, structural regions that ensure chromosomes segregate properly during cell division. Centromeres are a challenge to study because they contain repetitive DNA sequences and few genes. The goal of this project is to develop an understanding of how the sequences in centromeres relate to their function, and how changes in centromere size or changes in a key centromere binding protein (CENH3) can alter the behavior of centromeres. In particular the project will study genetic crosses and mutants that can induce centromere failure and chromosome loss in hybrids. Chromosome loss induced by centromere modification can result in haploid plants, which are of great value to corn breeders, as they can rapidly accelerate the production of new inbred lines. It is anticipated that the information and technology generated will have direct applications to agriculture - not only in maize but all other crops that utilize haploids as a breeding tool. With regards to training and outreach, the project will provide research training for undergraduate and graduate students as well as postdoctoral fellows in plant genomics and biotechnology. In addition, a series of training workshops will be held to disseminate techniques and materials generated in this project. All project outcomes will be made available to the research community through a dedicated project web site and through dissemination by long-term repositories that include NCBI, MaizeGDB and Gramene. The overall goals of the project are to understand the genetic and epigenetic components of maize centromeres and to reveal the role of centromere size in uniparental chromosome elimination which leads to haploid formation. The specific objectives are to: 1) determine whether common centromere repeat sequences are sufficient to induce centromere function using novel chromosome painting probes, chromosome visualization tools that dramatically improve the ability to detect changes in chromosome structure; 2) determine how a suite of chromatin markers are affected by changes in centromere size and location using maize chromosomes transferred into oat as well as B chromosomes that have undergone a cycle of inactivation and reactivation; 3) test whether centromere size disparity can cause uniparental genome elimination by screening lines with centromeres whose size have been modified by manipulating genome size, and by using cenh3 mutants with specialized transgenes; and 4) determine how maize centromeres behave in situations of uniparental genome elimination, particularly in wheat X maize and oat X maize crosses that are regularly used in haploid breeding schemes.