Functional Genomics of Maize Centromeres

PI：R。Kelly Dawe（University of Georgia-Athens）Co-PI：James A. Birchler（密苏里大学-哥伦比亚分校）和Jiming Jiang（威斯康星大学-麦迪逊分校）所有植物基因组都含有着丝粒，着丝粒是确保染色体在细胞分裂过程中正确分离的结构区域。着丝粒的研究是一个挑战，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（CENH 3）的变化如何改变着丝粒的行为。 特别是，该项目将研究遗传杂交和突变体，可以诱导杂交中的着丝粒失败和染色体丢失。由着丝粒修饰引起的染色体丢失可以产生单倍体植株，这对玉米育种者具有重要价值，因为它们可以快速地促进新自交系的产生。预计所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。关于培训和外联，该项目将为本科生和研究生以及博士后研究员提供植物基因组学和生物技术方面的研究培训。 此外，还将举办一系列培训讲习班，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通过包括NCBI、MaizeGDB和Gramene在内的长期资料库的传播提供给研究界。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，从而导致单倍体形成。具体的目标是：1）确定共同的着丝粒重复序列是否足以诱导着丝粒功能，使用新的染色体绘画探针，染色体可视化工具，显着提高检测染色体结构变化的能力;（二）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，使用玉米染色体转移到燕麦以及B染色体，已经经历了失活和再活化的循环; 3）通过筛选具有通过操纵基因组大小而改变了大小的着丝粒的品系，以及通过使用具有特化转基因的cenh 3突变体，来测试着丝粒大小差异是否可以引起单亲基因组消除;以及4）确定玉米着丝粒在单亲基因组消除的情况下如何表现，特别是在通常用于单倍体育种方案的小麦×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.