Functional Genomics of Maize Centromeres

主持：R. Kelly Dawe （University of Georgia-Athens）合作主持：James A. Birchler （University of Missouri-Columbia）和Jiming Jiang （University of Wisconsin-Madison）所有植物基因组都包含着丝粒，这是一种确保染色体在细胞分裂过程中正确分离的结构区域。着丝粒的研究具有挑战性，因为它们含有重复的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遗传杂交和突变，可以诱导着丝粒失败和染色体丢失的杂交。着丝粒修饰导致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的自交系的产生。预计所产生的信息和技术将直接应用于农业——不仅应用于玉米，而且应用于所有其他利用单倍体作为育种工具的作物。在培训和外联方面，该项目将为植物基因组学和生物技术方面的本科生、研究生和博士后提供研究培训。此外，还将举办一系列培训讲习班，以传播在这个项目中产生的技术和材料。所有的项目成果都将通过一个专门的项目网站以及NCBI、MaizeGDB和Gramene等长期知识库的传播提供给研究社区。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体染色体消除中导致单倍体形成的作用。具体目标是：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；2)确定一组染色质标记如何受到着丝粒大小和位置变化的影响，使用转移到燕麦中的玉米染色体以及经历失活和再激活周期的B染色体；3)通过筛选通过操纵基因组大小改变着丝粒大小的系，以及使用带有特化转基因的cenh3突变体，检验着丝粒大小差异是否会导致单代基因组消除；4)确定玉米着丝粒在单倍体基因组消除情况下的表现，特别是在单倍体育种计划中经常使用的小麦X玉米和燕麦X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.