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首页> 外文学位 >Genetic analysis of tocochromanol variation in maize using high-density linkage mapping.
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Genetic analysis of tocochromanol variation in maize using high-density linkage mapping.

机译：利用高密度连锁图谱分析玉米生育酚的变化。

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摘要

Vitamin E is an essential nutrient in the human diet and refers to eight distinct compounds that are collectively known as tocochromanols. Tocochromanols are grouped into two classes: tocotrienols and tocopherols. Tocochromanols are the major lipid-soluble antioxidants in maize (Zea mays L.) grain. Enhancing the tocochromanol content of maize derived foods through plant breeding has important nutritional and health implications. Chapter one is a literature review that provides a foundational understanding of the biosynthesis, function and genetic control of tocochromanols in plants, with specific attention to maize (Zea mays L.). Upon this foundation two research objectives were developed that work towards a better understanding of the genetic architecture of tocochromanols in plants. The two research objectives are (1) to investigate the genetic architecture of tocochromanol variation in maize (2) to explore the differences in genetic information explained by the data produced by two tocochromanol phenotyping methods. The first research objective is addressed in chapter two, in which high-density linkage mapping was used to explore the genetic architecture of tocochromanol content variation in two biparental maize populations. The second research objective is addressed in chapter three in which two biparental maize populations were phenotyped with two phenotyping systems to determine the ability of these two systems to effectively provide useful phenotypic information for the study of genetic architecture of tocochromanol variation in maize.;Variation for tocochromanol content was previously assessed in a maize inbred association panel. The research presented in chapter two and three utilized four inbred lines exhibiting unique tocochromanol variation that were chosen from the maize inbred association panel, because the maize nested association mapping (NAM) founders did not exhibit unique variation for the tocochromanol compounds of interest. The NAM population is under study for tocochromanols. These four inbred lines were chosen to construct two biparental mapping populations, N6xNC296 and E2558WxCo125, which were developed to further dissect the genetic architecture of tocochromanol variation in maize grain. The N6xNC296 population exhibits variation for &agr;-tocopherol and &agr;-tocotrienol content. The E2558WxCo125 population exhibits variation in the ratio of total tocotrienol to total tocopherol. The populations were genotyped using genotyping-by-sequencing (GBS) and high-density linkage maps were constructed. Each of the two high-density genetic maps contain over 1,200 single nucleotide polymorphism (SNP) markers. The tocopherol and tocotrienol variation in two replicates of each population was quantified using high performance liquid chromatography (HPLC). Composite interval mapping identified a novel QTL associated with tocopherol ratio traits that contains homogentisate phytyl transferase (ZmVTE2) in the support interval. Overall this work illustrates the complementary nature of biparental mapping populations to genome wide association studies in order to further dissect genetic variation and potentially detect rare alleles.;The genetic architecture of tocochromanols was further dissected by comparing the relative ability of two phenotyping methods to produce similar and accurate data to be used in genetic analysis. Recent advances in next-generation sequencing have drastically reduced the cost of genotyping. With such a vast reduction in resource use for genotyping, scientists can now examine phenotyping methods used to explore the genetic architecture of a given trait across the genome of the target plant species. Biochemical phenotyping is the determination of the steady state concentrations of a spectrum of biological compounds. The research presented in chapter three examines the efficacy of two biochemical phenotyping systems at determining the genetic architecture of tocochromanol variation in maize.;The two phenotyping systems under comparison are well-tested robust methods that provide an accurate representation of tocochromanol phenotyping systems. There were moderate to strong correlations between the tocochromanol content data provided by the phenotyping systems. The two systems produced relatively similar QTL results, with some slight differences. The higher throughput biochemical phenotyping system detected a QTL with the ZmVTE2 gene in the support interval, which had not been previously reported in maize. The differences in these genetic results are likely due to differences in the extraction and chromatography methodologies. Overall the research presented in chapter three suggests that genetic mapping precision is not lost by implementing a system that utilizes microtitre plate technology over the standard methods. Furthermore, this research reinforces that time and attention is needed to develop precise and accurate high-throughput phenotyping systems that allow the genetic architecture of quantitative traits to be explored with greater precision.
机译：维生素E是人类饮食中必不可少的营养素，是指八种不同的化合物，统称为生育酚。生育铬色素分为两类：生育三烯酚和生育酚。生育酚是玉米（Zea mays L.）谷物中主要的脂溶性抗氧化剂。通过植物育种提高玉米衍生食品中的生育酚铬醇含量具有重要的营养和健康意义。第一章是一篇文献综述，提供了植物中生育酚的生物合成，功能和遗传控制的基础知识，并特别关注了玉米（Zea mays L.）。在此基础上，制定了两个研究目标，以更好地理解植物中生育酚的遗传结构。两个研究目标是（1）研究玉米中生育酚的变化的遗传结构（2）探索两种生育酚表型分析方法产生的数据所解释的遗传信息差异。第二章讨论了第一个研究目标，其中使用高密度连锁作图探索了两个双亲玉米群体中生育酚铬醇含量变异的遗传结构。在第三章中讨论了第二个研究目标，其中两个双亲玉米种群通过两个表型系统进行表型确定，以确定这两个系统有效提供有用表型信息的能力，以研究玉米生育酚的遗传结构。以前在玉米近交协会中评估了生育酚铬酚的含量。在第二章和第三章中进行的研究利用了四个自交系显示出的生育酚铬色素的独特变化，这是从玉米近交协会面板中选择的，因为玉米巢式关联图谱（NAM）的建立者并未显示出感兴趣的生育酚的化合物具有独特的变异。 NAM人群正在研究生育酚。选择这四个自交系来构建两个双亲作图种群N6xNC296和E2558WxCo125，它们被开发用于进一步剖析玉米籽粒中生育酚的变化的遗传结构。 N6xNC296群体的α-生育酚和α-生育三烯酚含量存在差异。 E2558WxCo125群体的总生育三烯酚与总生育酚之比表现出差异。使用测序基因分型（GBS）对种群进行基因分型，并构建高密度连锁图谱。这两个高密度遗传图谱均包含1,200多个单核苷酸多态性（SNP）标记。使用高效液相色谱（HPLC）定量每个种群中两次重复的生育酚和生育三烯酚变化。复合间隔图谱鉴定了与生育酚比率性状相关的新型QTL，该QTL在支持区间中包含尿黑酸植酸转移酶（ZmVTE2）。总的来说，这项工作说明了双亲作图种群与全基因组关联研究的互补性质，以便进一步剖析遗传变异并潜在地检测稀有等位基因。通过比较两种表型鉴定方法产生相似物质的相对能力，进一步剖析了生育酚铬烷醇的遗传结构。以及用于基因分析的准确数据。下一代测序的最新进展已大大降低了基因分型的成本。随着基因分型资源的大量减少，科学家现在可以研究用于探索目标植物物种基因组中给定性状的遗传结构的表型方法。生化表型是确定一系列生物化合物的稳态浓度的方法。第三章中的研究检查了两种生化表型系统在确定玉米生育酚浓度变异的遗传结构中的功效。比较中的两个表型鉴定方法是经过充分测试的鲁棒方法，可准确代表生育酚浓度表型。表型系统提供的生育酚铬酚含量数据之间存在中等至强的相关性。这两个系统产生了相对相似的QTL结果，但有一些细微差异。高通量生化表型系统检测到在支持区间内带有ZmVTE2基因的QTL，这在玉米中以前没有报道。这些遗传结果的差异可能是由于提取和色谱方法的差异。总体而言，第三章提出的研究表明，通过实施在标准方法上利用微量滴定板技术的系统，不会丧失基因定位的准确性。此外，这项研究强调需要时间和精力来开发精确，准确的高通量表型系统，从而可以更精确地探索数量性状的遗传结构。

著录项

  • 作者

    Fenton, Megan E.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Plant sciences.;Botany.;Genetics.
  • 学位 M.S.
  • 年度 2015
  • 页码 129 p.
  • 总页数 129
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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