RESEARCH-PGR: Defining the Sumoylation System in Maize and Its Roles in Stress Protection

作物需要适当的机制在不利环境下生存和生长，以保持高产。最近，一种名为SUMO的小蛋白质被发现，它似乎可以保护植物免受高温和干旱等环境压力的影响。最近对暴露于环境胁迫下的植物进行的实验表明，SUMO蛋白可能会显著影响这些不利条件下基因的表达方式。SUMO蛋白迅速且可逆地附着在一组在环境胁迫下影响基因表达模式的蛋白上。该项目的目标是了解SUMO在逆境中的功能，并确定在作物中操纵SUMO是否可能为提高逆境耐受性提供新的途径。该项目将描述SUMO蛋白的作用模式，并确定在压力下与SUMO相互作用的所有其他蛋白质。为了帮助理解SUMO如何帮助玉米在压力下生存，我们还将确定为什么缺少关键成分的玉米突变体现在对压力非常敏感。总的来说，这项基础研究将确定玉米SUMOylation的关键点，这些关键点可以用来改善玉米和其他作物的胁迫保护。该项目将在圣路易斯华盛顿大学培养博士后、研究生和本科生。它还将开发与SUMO和抗逆性相关的可专利技术，以可持续地提高粮食和生物燃料作物的产量。SUMO在真核生物中是一种有影响力的调节剂，在翻译后加入其他细胞内蛋白后起作用。最近对拟南芥的研究发现，SUMOylation选择性地修饰胁迫期间的一些关键调控因子，这些调控因子影响染色质可及性、DNA/组蛋白修饰、转录、核孔功能和mRNA加工/输出。它们的联合活动表明，应激诱导的SUMOylation有助于植物可逆地调节染色质结构和由此产生的RNA景观，以更好地在不利条件下生存。不幸的是，SUMO缺乏对作物的欣赏，从而阻碍了对农业利益的理性重新设计。为了克服这一知识差距，本项目将定义SUMO化如何在玉米（Zea mays）中起作用，并利用我们最近通过蛋白质组学方法成功创建的种质来研究SUMO。本项目将：(i)描述玉米SUMO系统如何在生物化学上起作用并对各种环境挑战作出反应；（ii）将表达标记SUMO的转基因系与已建立的质谱方法结合起来，以定义玉米“summoylome”及其连锁位点；（iii）定量确定单个目标的summoylome状态如何受到胁迫的影响。（iv）通过对Mu转位或CRISPR/Cas9基因编辑技术产生的系统突变体的表型和生化分析，了解SUMO如何帮助玉米在不利环境中生存。总的来说，该项目将产生急需的试剂、技术和突变体，这些试剂、技术和突变体将有助于确定SUMO如何在胁迫下重组玉米染色质及其转录组，并确定SUMO化的关键点，这些关键点可以通过操纵来改善许多作物物种的胁迫保护。

Crop plants require suitable mechanisms to survive and perform well under unfavorable environments in order to maintain high productivity. Recently, a small protein called SUMO was discovered, and it appears to protect plants against environmental stresses like heat and drought. Recent experiments with plants exposed to environmental stresses have shown that the SUMO protein may significantly affect how genes are expressed under those unfavorable conditions. The SUMO protein becomes rapidly and reversibly attached to a group of proteins that affect the pattern of gene expression during environmental stress. The goals of this project are to understand the functions of SUMO during stress and determine whether its manipulation in crops might provide novel approaches to improve stress tolerance. This project will characterize the mode of action of the SUMO protein, and identify all the other proteins that interact with SUMO under stress. To help understand how SUMO helps maize survive stress, we will also determine why maize mutants missing key components are now hypersensitive to stress. Collectively, this fundamental research will identify key points in maize SUMOylation that can be exploited to improve stress protection, not only in maize but in other crops as well. This project will train postdocs, graduate students, and undergraduates at Washington University in St. Louis. It will also develop patentable technologies related SUMO and stress tolerance that can sustainably enhance food and biofuel crop yield.SUMO is an influential regulator in eukaryotes that works following its post-translation addition to other intracellular proteins. Recent studies with Arabidopsis discovered that SUMOylation selectively modifies a number of critical regulators during stress that impact chromatin accessibility, DNA/histone modification, transcription, nuclear pore function, and mRNA processing/export. Their combined activities imply that stress-induced SUMOylation helps plants reversibly adjust chromatin architecture and the resulting RNA landscape to better survive adverse conditions. Unfortunately, appreciation of SUMO is lacking for crops, thus precluding rational redesign for agricultural benefit. To overcome this knowledge gap, this project will define how SUMOylation works in maize (Zea mays), using as essential backdrops our recent success in creating germplasm to study SUMO via proteomic approaches. This project will: (i) describe how the maize SUMO system works biochemically and responds to various environmental challenges, (ii) combine transgenic lines expressing tagged SUMOs with established mass spectrometric methods to define the maize 'SUMOylome' and its linkage sites, (iii) determine quantitatively how the SUMOylation status of individual targets is impacted by stress, and (iv) understand how SUMO helps maize survive adverse environments through the phenotypic and biochemical analyses of system mutants generated by either Mu transposition or CRISPR/Cas9 gene editing technologies. Collectively, this project will generate much-needed reagents, techniques, and mutants that will help define how SUMO reorganizes maize chromatin and its transcriptome during stress, and identify key points in SUMOylation that can be manipulated to improve stress protection in many crop species.