Genetic and Epigenetic Regulation of Gametophyte Development and Transposon Expression in Maize

PI：Matthew M. S.埃文斯（华盛顿卡内基研究所）CoPIs：唐纳德L。Auger（南达科他州州立大学），John E.福勒（俄勒冈州州立大学），R。基思斯洛特金（俄亥俄州州立大学）和埃里克W。Volbrecht（爱荷华州州立大学）高级合作者：Allison菲利普斯（威斯康星州路德学院）和Jennifer Eustaquio（斯坦福大学）该项目包括表观遗传学和基因表达的基础研究，因此可能对重要植物性状的表现有广泛的影响，特别是在基因组中有大量转座子的作物中。更具体地说，配子体是植物繁殖的核心;因此，本项目直接关系到几个农业目标（例如，控制花粉育性、限制花粉介导的转基因流动、诱导无融合生殖），特别是考虑到该项目的重点是一种重要的作物玉米。此外，该项目将为其他研究人员提供一个数据框架，以确定配子体如何发挥作用以及如何操纵它们以产生改良的作物。该项目将通过合作实验室之间的频繁交流，以跨学科的方式培养一批本科生、研究生和研究生科学家。本科生将获得现代实验室技术以及大规模数据集计算分析的经验。本科生将同时通过斯坦福大学的科学服务项目接受研究人员和教育工作者的培训。本科生学习成为高中生的科学导师，并开发实验室课程，然后在本科生导师的监督下由当地高中课程执行。作为该项目的一部分，来自高中课程的学生也参加了该项目，接触遗传学和图像分析。在开花植物的花组织内，多细胞单倍体雌性和雄性配子体产生配子，配子经过受精产生种子。虽然配子体很小，很少进行细胞分裂，但它们对产生下一代至关重要，并执行各种生物过程。植物种子的形成和繁殖以及全球农业都依赖于配子体的功能。尽管配子体在植物繁殖中起着重要作用，但由于其体积小且嵌入亲本组织中，其功能和发育在很大程度上被忽视。玉米基因组，像许多作物植物基因组一样，含有大量的移动的DNA元件，称为转座子，并且通常通过调节表观遗传状态来控制这些元件对于维持基因功能和基因组结构是至关重要的。配子体有助于在下一代中建立表观遗传状态，然而，特别是在雌性配子体中，关于转座子表达如何调节以及这种控制如何影响蛋白质编码基因的同时表达，人们知之甚少。该项目将利用组织显微解剖技术和全基因组分析来了解玉米两性配子体表观遗传状态和细胞功能的发育调控机制。该项目将筛选在配子体发育中起作用的新突变体和基因;对基因、转座子和不同类别的RNA的表达进行全基因组分析，并提供细胞细节;生成转座子活性的可视化报告;并表征转座子在发育配子体中的表达。该项目将确定基因和转座子在配子体发育中的空间和时间表达模式，以及定义它们如何在配子体发育中发挥作用。相关突变体对转座子表达的影响有望增加对重要作物玉米中基本配子体发育和转座子活性控制之间相互作用的理解。该项目产生的序列基因表达数据将通过项目网站（www.maizegametophyte.org）和国家生物技术信息基因表达综合中心（www.ncbi.nlm.nih.gov/geo）以及玉米遗传学和基因组学数据库（maizegdb.org）广泛访问。种子储备将存放在玉米遗传合作储备中心。

PI: Matthew M. S. Evans (Carnegie Institution of Washington)CoPIs: Donald L. Auger (South Dakota State University), John E. Fowler (Oregon State University), R. Keith Slotkin (The Ohio State University) and Erik W. Volbrecht (Iowa State University)Senior Collaborators: Allison Phillips (Wisconsin Lutheran College) and Jennifer Eustaquio (Stanford University)This project comprises foundational research on epigenetics and gene expression, and thus may have broad implications for the manifestation of important plant traits, particularly in crops with large numbers of transposons in their genomes. More specifically, gametophytes are central to plant reproduction; thus this project is directly relevant to several agricultural objectives (e.g., controlling pollen fertility, limiting pollen-mediated transgene flow, inducing apomixis), particularly given the project's focus on a crucial crop plant, maize. Additionally, the project will provide a data framework for other researchers to determine how gametophytes function and how they can be manipulated to generate improved crop plants. This project will train a number of undergraduate, graduate and post-graduate scientists in an interdisciplinary fashion through frequent exchanges between the partnering laboratories. Undergraduates will gain experience in modern laboratory techniques as well as computational analysis of large-scale data sets. Undergraduate students will simultaneously be trained as researchers and educators through Stanford University's Science in Service Program. Undergraduates learn to be Science Mentors for high school students and develop laboratory curricula that are then performed by local high school programs under the supervision of the undergraduate mentors. As part of the project, students from the high school programs also participate in the project, getting exposure to genetics and image analysis. Within the floral tissues of flowering plants, multicellular haploid female and male gametophytes produce the gametes that undergo fertilization to produce seeds. Although gametophytes are small and undergo few cell divisions, they are crucial for producing the next generation, and execute diverse biological processes. Plant seed formation and reproduction, and thus global agriculture, are dependent on gametophyte function. In spite of their critical role in plant reproduction, gametophyte function and development has largely been overlooked due to their small size and imbedded location within the parental tissue. The maize genome, like many crop plant genomes, harbors a large number of mobile DNA elements, called transposons, and control of these elements, often through regulation of epigenetic states, is critical for maintenance of gene function and genome structure. Gametophytes help set epigenetic states in the next generation, however little is known, especially in the female gametophyte, about how transposon expression is regulated, and how that control impacts the concurrent expression of protein-coding genes. This project will use tissue micro-dissection techniques and whole genome analysis to understand the mechanisms that underlie developmental regulation of epigenetic states and cellular functions in the gametophytes of both sexes in maize. This project will screen for new mutants and genes that function in gametophyte development; perform genome-wide analysis of expression of genes, transposons, and different classes of RNAs with cellular detail; generate visual reporters for transposon activity; and characterize transposon expression in developing gametophytes. This project will determine the spatial and temporal expression pattern for genes and transposons in developing gametophytes, as well as define how they function to program gametophyte development. The effect of relevant mutants on transposon expression is expected to increase understanding of the interaction between basic gametophyte development and control of transposon activity in the important crop plant, maize. The sequence gene expression data generated from this project will be widely accessible through the project website (www.maizegametophyte.org) and the National Center for Biotechnology Information Gene Expression Omnibus (www.ncbi.nlm.nih.gov/geo), and the Maize Genetics and Genomics Database (maizegdb.org). Seed stocks will be deposited with the Maize Genetics Cooperation Stock Center.