An Integrated Phenomics Approach to Identifying the Genetic Basis for Maize Root Structure and Control of Plant Nutrient Relations

在气候变化的情况下提高产量和作物生产的可持续性是我们这个时代最重要的挑战之一。玉米是美国最重要的作物，尽管玉米产量稳步增长，但预计产量仍无法满足需求。此外，石油基氮肥已被确定为美国和全球主要水道污染的主要驱动因素。这个项目的重点是根系，植物的“隐藏的一半”，它负责所有的水、氮和其他营养物质的获取。它利用先进的成像技术，其中一些是在医学和工业研究部门开发的，来分析根系的结构。我们将比较氮吸收能力较强的玉米品种的根系结构，并鉴定控制根氮相互作用的基因。通过鉴定控制根系生长和有效氮获取的基因，这将直接使玉米和其他作物育种者受益，从而成为美国农业的一个主要部门。另一个目标是，为中学生和大学生设立课外和暑期教育项目，培养下一代科学家。这些学员将获得第一手的经验建设，编程，并使用3D打印机和负担得起的微处理器采用植物成像系统。要实现根系在逆境下提高和稳定作物产量以及减少不可持续的肥料使用水平方面的巨大潜力，就需要对根系的遗传学和生理学有透彻的了解。基于图像的表型分析使根的高通量和精确测量成为可能，但是尽管有许多新的和有前途的方法，每种方法都有固有的权衡，限制了它们各自的能力。本项目采用综合根系现象和生理分析方法来解决玉米根系构型的遗传基础和功能后果。它将以四种互补的方式描绘两个玉米群体的根系结构：凝胶基系统中幼植株的3D/4D成像，从田间挖掘的根冠的光学和x射线成像，以及在田间土壤剖面中生长的根系的微型微波成像。从这些方法中进行的定量遗传分析将允许鉴定控制这些性状的基因。此外，这种对相同基因型的综合分析将产生迄今为止最全面的根表型方法比较。一个群体将在项目的头两年从NAM亲本系筛选中选择，另一个群体将是伊利诺伊州蛋白株重组自交系（IPSRIs）。在五年内，这一办法将实现以下目标：鉴定驱动根构型表型变异的基因；2 .确定控制根系构型对氮供应表型可塑性的基因；确定根系构型对植物氮素状态、元素含量和种子品质的功能影响。

Increasing the yield and sustainability of crop production in a changing climate is one of the foremost challenges of our time. Corn is the most important crop in the United States, but despite steady increases in corn production, projected yields fall short of demands. Furthermore, petroleum-based nitrogen fertilizers have been identified as a primary driver of pollution of major waterways in the U.S. and globally. This project focuses on root systems, the "hidden-half" of plants, that are responsible for all of the water, nitrogen, and other nutrient acquisition. It leverages advanced imaging techniques, some of which were developed in the medical and industrial research sectors, to analyze the structure of root systems. Root structures from corn varieties that are known to be superior in nitrogen acquisition will be compared those that are inferior, and the genes that control root-nitrogen interactions will be identified. This will directly benefit corn and other crop breeders, and thus a major sector of U.S. agriculture, through identification of genes that control root growth and efficient nitrogen acquisition. An additional objective is to train the next generation of scientists by establishing after-school and summer educational programs for middle-school to undergraduate students. These trainees will gain first-hand experience building, programming, and employing plant imaging systems using 3D printers and affordable microprocessors.Realizing the enormous potential of root systems to boost and stabilize crop yields under stress and to reduce unsustainable levels of fertilizer use will require a thorough understanding of their genetics and physiology. Image-based phenotyping has enabled high-throughput and accurate measurements of roots, but despite many new and promising methods, each has inherent tradeoffs that limit their individual power. This project employs an integrated root phenomic and physiological profiling approach to resolve the genetic basis and functional consequences of maize root architecture. It will profile the root architecture of two maize populations in four complementary ways: 3D/4D imaging of young plants in a gel based system, optical and X-ray based imaging of root crowns excavated from the field, and minirhizotron imaging of roots growing across the soil profile in the field. Quantitative genetic analyses from each of these methods will allow identification of the genes controlling these traits. Additionally, this integrated analysis of identical genotypes will generate the most comprehensive comparison of root phenotyping methods to date. One population will be selected from screening of the NAM parent lines in the first two years of the project, the other population will be the Illinois Protein Strain Recombinant Inbreds (IPSRIs). Over five years, this approach will address the following aims: 1. Identify genes driving phenotypic variation of root architecture, 2. Identify genes controlling phenotypic plasticity of root architecture to nitrogen supply, 3. Determine the functional impacts of root architecture on plant nitrogen status, elemental content and seed quality.