RESEARCH-PGR: Genomic Balance Analysis in Maize

RESEARCH-PGR：玉米基因组平衡分析

• 批准号: 1545780
• 负责人: James Birchler
• 金额: $ 198.25万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1545780&HistoricalAwards=false
• 关键词: RESEARCH; PGR; Genomic; Balance; Analysis

Genetic information in plants and animals is carried in the DNA of pairs of chromosomes that are carried forward from generation to generation. Change in the numbers, or doses, of individual chromosomes is known to occur, usually with detrimental effects on the stature and health of the affected organism. Surprisingly, there are no obvious differences if the entire set of chromosomes change. This phenomenon has puzzled scientists for decades: what features of the genome maintain balance when fully altered, but are imbalanced when only some chromosomes are affected? This project will examine how and why this partial change in the chromosomes has such an impact on plants. Maize is an ideal model for this study due to its global crop importance and also because of the powerful genetic resources available to test how the so-called genome balancing act occurs. One hypothesis is that the relative expression of regulatory genes, which are the factors that control the expression of other genes, has a significant impact on development and vigor of plants. The research identifies the underlying molecular mechanisms involved in maintaining genomic balance. This knowledge is essential to understand how plant vigor is controlled and will provide information about the traits needed for improving agriculture. Students and educators of all levels are engaged in addressing this problem through direct hands-on research, via social media outlets and outreach workshops. Understanding how regulatory dosage effects operate will guide breeding programs for crop improvement and will answer basic questions about how plant genomes function.This project is based on a synthesis emerging from the idea of genomic balance known from classical genetics and more recent molecular studies. The overall hypothesis is that the stoichiometry of assembly of multisubunit gene regulatory complexes affects the function of the whole, which will impact global gene expression and ultimately the phenotype. The analysis of genomic balance issues will address: (1) how genomic imbalance affects gene expression levels of mRNA, siRNA, and miRNA as the baseline for understanding the circuitry involved; (2) how small RNAs are involved with genomic balance in modulating mRNA levels and how genomic balance affects small RNA levels; (3) how genomic imbalance impacts and/or operates through chromatin modifications; and (4) how genomic imbalance works on the single gene level by examining the effect of varying the dosage of single subunits on whole complex formation and function. These aspects will be studied in a set of aneuploids generated by translocation with the supernumerary B chromosome of maize that can be used to vary selected chromosome arms in haploid and diploid plants. By examining more complex changes in dosage with greater or lesser genomic imbalance, how the interactions of regulatory processes alter various aspects of gene expression will be tested. Single regulatory gene candidates responsible for target gene modulations will be examined in a transgenic dosage series to gain insight into the mechanism of genomic balance. Together, the information from all of these fields will contribute to an understanding of genomic balance and allow this information to be applied to issues of world food production.

植物和动物的遗传信息携带在一对染色体的DNA中，这些染色体被代代相传。已知个体染色体的数量或剂量发生变化，通常对受影响有机体的身高和健康造成有害影响。令人惊讶的是，如果整组染色体发生变化，没有明显的差异。这一现象几十年来一直困扰着科学家：基因组的哪些特征在完全改变时保持平衡，但当只有部分染色体受到影响时却是不平衡的？这个项目将研究染色体的这种部分变化如何以及为什么会对植物产生如此大的影响。玉米是这项研究的理想模型，因为它在全球作物中的重要性，也因为有强大的遗传资源可用于测试所谓的基因组平衡行为是如何发生的。一种假说认为，调控基因的相对表达是控制其他基因表达的因素，对植物的发育和活力有重大影响。这项研究确定了维持基因组平衡的潜在分子机制。这一知识对于理解植物活力是如何被控制的是必不可少的，并将提供有关改良农业所需性状的信息。各级学生和教育工作者通过社交媒体渠道和外联讲习班，通过直接动手研究，参与解决这一问题。了解调节剂量效应是如何运作的，将指导作物改良的育种计划，并将回答有关植物基因组如何功能的基本问题。这个项目是基于从经典遗传学和最近的分子研究中已知的基因组平衡的想法而产生的综合。总体假设是，多亚单位基因调控复合体组装的化学计量学影响整体的功能，这将影响全球基因表达，并最终影响表型。基因组平衡问题的分析将解决：(1)基因组失衡如何影响mRNA、siRNA和miRNA的基因表达水平，以此作为理解相关电路的基线；(2)小RNA如何参与调节mRNA水平的基因组平衡，以及基因组平衡如何影响小RNA水平；(3)基因组失衡如何通过染色质修饰影响和/或操作；以及(4)基因组失衡如何在单基因水平上发挥作用，方法是检查单个亚基的剂量对整个复合体形成和功能的影响。这些方面将在一组由玉米多余的B染色体易位产生的非整倍体中进行研究，这些非整倍体可以用来改变单倍体和二倍体植物中选定的染色体臂。通过检查更复杂的剂量变化和更大或更小的基因组失衡，将测试调控过程的相互作用如何改变基因表达的各个方面。负责靶基因调控的单个调控基因候选将在转基因剂量系列中进行检查，以深入了解基因组平衡的机制。总之，所有这些领域的信息将有助于理解基因组平衡，并使这些信息能够应用于世界粮食生产问题。