RESEARCH-PGR: Genomic Balance Analysis in Maize

植物和动物的遗传信息携带在成对染色体的DNA中，代代相传。已知单个染色体的数量或剂量会发生变化，通常会对受影响生物体的身材和健康产生有害影响。令人惊讶的是，如果整个染色体组发生变化，则没有明显的差异。这个现象让科学家们困惑了几十年：基因组的哪些特征在完全改变时保持平衡，而在只有一些染色体受到影响时却不平衡？该项目将研究染色体的这种部分变化如何以及为什么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对植物的发育和活力有重要影响，调控基因是控制其他基因表达的因素。该研究确定了维持基因组平衡的潜在分子机制。这些知识对于了解植物活力是如何控制的至关重要，并将提供有关改善农业所需性状的信息。各级学生和教育工作者通过直接的实践研究，通过社交媒体渠道和外展研讨会，参与解决这一问题。了解调节剂量效应如何运作将指导作物改良育种计划，并将回答有关植物基因组如何发挥作用的基本问题。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合成的。总体假设是，多亚基基因调控复合物组装的化学计量影响整体功能，从而影响整体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，作为理解相关电路的基线；(2)小RNA如何参与基因组平衡调节mRNA水平，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/或运作；(4)通过检测不同剂量的单个亚基对整个复合物形成和功能的影响，研究基因组失衡在单基因水平上的作用机制。这些方面将在一组非整倍体中进行研究，这些非整倍体是由玉米的多余B染色体易位产生的，可以用来改变单倍体和二倍体植物中选择的染色体臂。通过检查更复杂的剂量变化与更大或更小的基因组失衡，将测试调节过程的相互作用如何改变基因表达的各个方面。负责靶基因调节的单调控基因候选物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，来自所有这些领域的信息将有助于了解基因组平衡，并允许将这些信息应用于世界粮食生产问题。

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.