Transcriptional Regulation of Maize Endosperm Development by IDD9 and IDDveg9 Duplicate Genes

胚乳是谷物的主要贮藏组织，对人类和牲畜的营养非常重要，并且越来越多地用于工业目的。胚乳包括几种不同的细胞类型，每种细胞类型都具有影响谷物的生化组成和农艺品质的特定生物学功能。了解这些细胞类型在发育过程中是如何被指定和阐述的，可以通过生物技术或传统育种来改善谷物特性。这个项目的重点是胚乳细胞类型称为糊粉。鉴定了控制糊粉层细胞数量以及糊粉层细胞特征发育的玉米基因。这种基因被称为nkd，在两条不同的染色体上复制，并编码一种称为IDD 9/IDDveg 9的转录因子（一种调节其他基因的蛋白质）。因此，该基因的功能是调节对胚乳发育重要的其他基因。本计画将利用分子及遗传学方法探讨nkd基因在胚乳发育中的生物学功能。该基因在控制胚乳发育的调控层次中的相对位置将通过检查正常玉米籽粒中的时间和空间表达模式与已知影响胚乳发育中的特定步骤的突变体相比来确定。基因表达的全基因组分析将揭示哪些基因受IDD 9/IDDveg 9调控。最后，将探索nkd基因和植物激素生长素之间的联系。这项研究有望确定胚乳（糊粉）发育调控的关键步骤和分子，除了生物学和潜在的农学意义外，还将为年轻科学家提供重要的培训机会。一名博士后研究员，一名研究生，三名本科生和三名暑期实习生将为这些研究活动做出贡献并从中受益。重点将放在从地区少数民族人口中征聘。

Endosperm is the major storage tissue of cereals and is vastly important for human and livestock nutrition and, increasingly, for industrial purposes. Endosperm comprises several different cell types, each with specific biological functions that influence the biochemical composition and agronomic quality of the grain. Understanding how these cell types are specified and elaborated during development could enable the improvement of grain properties through biotechnology or traditional breeding. This project focuses on an endosperm cell type called aleurone. A maize gene was identified that controls the number of aleurone cells as well as the development of aleurone cell characteristics. This gene, called nkd, is duplicated on two different chromosomes and codes for a transcription factor (a protein that regulates other genes) called IDD9/IDDveg9. As such, the function of this gene is to regulate other genes that are important for endosperm development. The project will use molecular and genetic approaches to explore the biological function of the nkd gene in endosperm development. The relative position of this gene in the regulatory hierarchy that controls endosperm development will be ascertained by examining the temporal and spatial expression patterns in normal maize grains compared to mutants that are known to affect specific steps in endosperm development. Genome-wide analysis of gene expression will reveal what genes are regulated by IDD9/IDDveg9. Finally, a link will be explored between the nkd gene and the plant hormone auxin. This research is expected to define key steps and molecules in the regulation of endosperm (aleurone) development.In addition to the biological and potential agronomic implications, important training opportunities will be afforded to young scientists. One postdoctoral fellow, one graduate student, three undergraduate students and three summer interns will contribute to, and benefit from, these research activities. Emphasis will be placed on recruiting from area minority populations.