Role of chromatin remodeling in gene regulation during maize basal endosperm development

玉米粒是全球食品、饲料、生物燃料、淀粉/糖和许多食品原料的来源。玉米籽粒的胚乳是营养物质的主要储存库。它由支持内核开发的几个功能独特的细胞层组成。本项目研究其中一个胚乳转移细胞（BETCs）的分子和生理发育过程。特别是，实验将表征三羧酸（TCA）循环代谢物及其副产物作为染色质结构和基因表达的重要决定因素的作用。包装成常染色质（开放染色质）通常导致基因表达增加，而包装成异染色质（封闭染色质）通常是基因沉默的标志，代谢物在调节这种包装中的直接作用是一个新的发现。该项目还将组织玉米基因沉默暑期实习（CornSInGS），为当地高中生提供动手实验室和实地练习，以了解作物性状的遗传。植物表型将用于证明基因沉默开关。该项目还将与弗吉尼亚州立大学的教师和本科生合作，进行本科生暑期实习，与康宁斯研讨会重叠。研究结果将提供对胚乳和健康玉米籽粒发育所需的细胞核生物过程的知识。基部胚乳转移细胞位于韧皮部末端的界面，连接着光合产物的来源（叶片）和淀粉质胚乳的储存细胞（库）。早期核发育事件的核心是细胞过程，包括DNA复制、转录和RNA剪接。这些基本过程中的任何一个调控不当都会导致细胞分化、生长和发育的缺陷。玉米ufo1 （Zmufo1； orange1的不稳定因子）突变体具有BETC缺陷，这些缺陷与TCA循环基因、代谢物、活性氧（ROS）和基本调控过程的异常表达有关。因此，Zmufo1突变体提供了一套不同的核缺陷和植物表型，以帮助表征细胞分化。这一建议将表征代谢和表观遗传调控事件，这些事件需要在早期基础胚乳发育期间维持细胞稳态。具体目标是：1.；表征氧化还原依赖性，时空染色质重塑在BETC分化过程中由Zmufo1调节。2. 表征zmufo1相关的蛋白质相互作用。3. 确认ZmUFO1预测的asf1组蛋白伴侣结构域的功能。从这个项目中获得的知识可以应用于理解其他特化细胞的发育，这些细胞支持其他具有经济意义的谷物的胚胎和胚乳。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Maize kernels are a global source of food, feed, biofuel, starches/sugars, and ingredients in many food products. The endosperm of the maize kernel is a primary reservoir of nutrients. It is composed of several functionally unique cell layers that support kernel development. This project investigates molecular and physiological processes of development in one such layer, the basal endosperm transfer cells (BETCs). In particular, experiments will characterize the role of tricarboxylic acid (TCA) cycle metabolites, as well as their byproducts, as important determinants of chromatin structure and gene expression. Packaging into euchromatin (open chromatin) often leads to increased gene expression, whereas packaging into heterochromatin (closed chromatin) is generally a marker of gene silencing, and the direct role for metabolites in regulating this packaging is a novel finding. The project will also organize Corn Summer Internships in Gene Silencing (CornSInGS) for hands-on laboratory and field exercises for local high school students to learn the inheritance of crop traits. Plant phenotypes will be used to demonstrate gene silencing switches. This project will also collaborate with faculty and undergraduates from Virginia State University for undergraduate summer internships overlapping with the CornSInGS workshop. Findings will provide knowledge of the biological processes in the nucleus that are required for the development of endosperm and a healthy maize kernel. Basal endosperm transfer cells lie at the interface of phloem termini connecting the source of photosynthates (leaves) with the storage cells (sink) of starchy endosperm. At the heart of early kernel developmental events are cellular processes, including DNA replication, transcription, and RNA splicing. Mis-regulation of any of these basic processes causes defects in cell differentiation, growth, and development. Maize ufo1 (Zmufo1; unstable factor for orange1) mutants have BETC defects that were found to be associated with aberrant expression of TCA cycle genes, metabolites, reactive oxygen species (ROS), and basic regulatory processes. Zmufo1 mutants therefore provide a varied set of kernel defects and plant phenotypes to help characterize cellular differentiation. This proposal will characterize metabolic and epigenetic regulatory events that are required to maintain cellular homeostasis during early basal endosperm development. Specific aims are: 1. Characterize redox-dependent, spatiotemporal chromatin remodeling during BETC differentiation as modulated by Zmufo1. 2. Characterize ZmUFO1-associated, protein-protein interactions. 3. Confirm functionality of the predicted ASF1-histone chaperone domain of ZmUFO1. The knowledge gained from this project can be applied to understand the development of other specialized cells supporting the embryo and endosperm of other cereal grains of economic importance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.