Gene Regulatory Networks in the Maize Endosperm

PI：拉明Yadegari（亚利桑那大学）CoPI：Philip W. Becraft（爱荷华州州立大学），Joanne M. Dannenhoffer（中密歇根大学）和加里N. Drews（犹他州大学）胚乳是种子的主要组成部分，并且在生物学和经济学上是重要的。在所有被子植物中，胚乳在种子发育过程中为胚提供营养和信号。在谷物中，胚乳构成了成熟种子的很大比例，并含有大量的碳水化合物和蛋白质，它们直接或间接地通过动物饲料提供了人类饮食中超过50%的卡路里。谷物胚乳也是制造重要工业产品的原料，包括乙醇。玉米是一个很好的模式系统的分子遗传学分析的谷物胚乳，是本研究项目的主要对象，重点是玉米早期胚乳发育，包括从一个单一的细胞发育成多细胞结构组成的不同特化的细胞类型的时间。 尽管控制这一发育期的分子机制尚未阐明，但它们可能影响许多经济上重要的过程，包括但不限于种子大小的调节以及籽粒灌浆期间淀粉和蛋白质的积累。除了对学生和博士后进行培训外，该项目还将为中密歇根大学的本科生提供暑期研究培训实习机会。 为了鉴定控制胚乳细胞分化的遗传途径，将在多个时间点对每种胚乳细胞类型进行基因表达谱分析;这将通过激光捕获显微切割收集特定胚乳细胞类型和RNA-seq方法（cDNA的高通量测序）的组合来完成，以鉴定在收集的组织中表达的所有基因。这一信息将被用作两种胚乳细胞类型的基因网络分析的框架：淀粉胚乳和基底转移层。淀粉质胚乳是淀粉和蛋白质积累的主要储存库，而基部转移层对于将糖和氨基酸构件运输到生长的谷粒中是重要的;这两种组织对于谷粒产量和品质都是重要的。基因网络将通过基因共表达分析来揭示，关键转录因子将通过蛋白质-DNA分析和遗传分析来研究。 早期胚乳发育对干旱胁迫高度敏感，即使恢复了有利的水分条件，干旱胁迫也会降低谷物产量。为了鉴定玉米籽粒中由干旱胁迫引起的基因表达扰动，将对来自干旱胁迫植物的籽粒进行基因表达谱分析。此外，该项目将分析在密切相关的谷物高粱中早期胚乳发育过程中表达的基因，并使用玉米比较基因组学来揭示胚乳发育的基本和物种特异性方面。生成的数据可通过项目网站（www.grainendosperm.org）以及MaizeGDB和NCBI的GEO和SRA等长期储存库访问。

PI: Ramin Yadegari (University of Arizona)CoPIs: Philip W. Becraft (Iowa State University), Joanne M. Dannenhoffer (Central Michigan University), and Gary N. Drews (University of Utah)Endosperm is a major component of the seed, and is biologically and economically important. In all angiosperms, endosperm provides nutrients and signals to the embryo during seed development. In cereal grains, endosperm composes a large proportion of the mature seed, and contains large amounts of carbohydrates and proteins, which provide more than 50% of the calories in the human diet, either directly or indirectly through animal feed. Cereal endosperm also serves as a raw material for manufacturing important industrial products, including ethanol. Maize is an excellent model system for molecular genetic analysis of cereal endosperm and is the primary subject of this research project which focuses on maize early endosperm development, encompassing the time when the endosperm grows from a single cell into a multicellular structure composed of different specialized cell types. Although the molecular mechanisms that control this developmental period have not been elucidated, they are likely to affect many economically important processes including, but not limited to, the regulation of seed size, and accumulation of starch and protein during grain filling. In addition to the training of students and postdoctoral associates, the project will provide summer research training internships for undergraduate students from Central Michigan University. To identify genetic pathways that control endosperm cell differentiation, gene expression profiling will be performed on each endosperm cell type at multiple time points; this will be accomplished through a combination of laser-capture microdissection to collect specific endosperm cell types and the RNA-seq method (high throughput sequencing of cDNA) to identify all the genes expressed in the collected tissues. This information will be used as a framework for gene-network analysis in two of the endosperm cell types: the starchy endosperm and basal transfer layer. Starchy endosperm is the major repository for starch and protein accumulation, while the basal transfer layer is important for transporting sugar and amino acid building blocks into the growing grain; both tissues are important for grain yield and quality. The gene networks will be revealed by performing gene co-expression analysis and key transcription factors will be studied with protein-DNA assays and genetic analyses. Early endosperm development is highly sensitive to drought stress which can decrease grain yield, even if favorable moisture conditions are restored. To identify the gene-expression perturbations caused by drought stress in maize kernels, gene expression profiling will be performed with kernels from drought-stressed plants. In addition, this project will profile the genes expressed during early endosperm development in a closely related cereal, sorghum, and use comparative genomics with maize to reveal fundamental and species-specific aspects of endosperm development. Data generated can be accessed through the project website (www.grainendosperm.org) as well as through long-term repositories such as MaizeGDB and NCBI's GEO and SRA.