The Role of Copper and Transcriptional Regulatory Networks Governing Copper Homeostasis in Pollen Fertility in A. thaliana.

由于目前的人口增长，全球对高产作物的需求正在增加，这一趋势迫使人们将边际土地用于农业目的。例如，土壤中有限的铜供应导致作物缺铜，这种情况导致植物不育，从而导致产量低下;然而，在严重缺铜的情况下，预计作物会完全歉收。尽管人们对植物如何从土壤中获得铜以及铜如何在植物中被调动有很多了解，但对铜如何影响植物肥力的了解不多。该项目将使用跨学科的方法提供铜在模式植物拟南芥的花粉发育和生育力中的作用的基本见解。更具体地说，该项目还将有助于解释SPL 7和新发现的CITF 1这两种蛋白质如何协调铜的吸收和向A.以及它们如何协调花粉发育和生育力。这种新的知识和理解将促进在目前耕作的土壤或边际土壤中发展粮食产量更高的作物。研究机会将提供给本科生和研究生，特别努力吸引妇女和代表性不足的少数民族。将开发一个多媒体网络模块“矿物质营养：从植物到人类”，目的是提高高中学生和K-12教师对微量营养素在植物生长和发育中的作用的认识，因为它涉及食品安全和人类福祉。虽然铜被认为是植物生育力所必需的微量营养素，但对铜向生殖器官的传递，或协调铜稳态和植物生殖的转录调控网络知之甚少。在拟南芥中，SPL 7是已知的唯一在铜稳态中起作用的转录因子。该项目基于PI实验室最近发现的CITF 1。CITF 1是bHLH家族的TF成员，其使A.使其在铜缺乏中存活。初步证据表明，CITF 1与SPL 7通路相互作用。破坏这种相互作用会导致幼苗死亡和花粉不育。铜在花药和花粉中的作用位点以及SPL 7-CITF 1在花粉发育中所起的作用将通过分析在不同铜水平下生长的突变株系来表征。同步辐射X射线荧光显微镜将用于图像（2D-3D）铜分布在花粉发育过程中。空气中扫描电子显微镜和组织学分析将用于表征铜水平对对照和突变株系解剖学和形态学的影响。有针对性的染色质免疫沉淀和功能性遗传分析将确定CITF 1的直接上游调控因子。全球表达谱分析加上计算共表达网络分析将揭示SPL 7和CITF 1的可能下游铜响应靶点，调控组分的层次结构及其与铜摄取的关系，以及器官分配和递送。长期目标是了解铜稳态的调控和信号网络，并将这些知识应用于生产适应低铜土壤的品种。

The global demand for high-yielding crops is increasing due to current population growth, a trend that is forcing the utilization of marginal lands for agricultural purposes. For instance, limited copper availability in the soil causes copper deficiency in crop plants, a condition that leads to plant infertility and consequently low yields; however, total crop failure can be expected under acute copper deficiencies. Although a great deal is known about how plants acquire copper from the soil, and how it is mobilized within the plant, not much is understood about how copper affects plant fertility. This project will use interdisciplinary approaches to provide fundamental insights on the role copper plays in pollen development and fertility in the model plant Arabidopsis thaliana. More specifically, this project will also help to explain how two proteins, SPL7 and the newly discovered CITF1, coordinate copper uptake and delivery to the reproductive organs of A. thaliana, and how they orchestrate pollen development and fertility. This new knowledge and understanding will facilitate the development of crops with better grain yields in soils currently under cultivation or marginal soils. Research opportunities will be offered to undergraduate and graduate students with a special effort to attract women and underrepresented minorities. A multi-media web module "Mineral nutrition: from plants to humans" will be developed with the intent to increase the awareness of high school students and K-12 teachers about the role of micronutrients in plant growth and development as it pertains to food safety and human well-being. Although copper is recognized as an essential micronutrient for plant fertility, very little is known about copper delivery to reproductive organs, or about transcriptional regulatory networks that coordinate copper homeostasis and plant reproduction. In Arabidopsis thaliana, SPL7 is the only transcription factor known to function in copper homeostasis. This project is based on the recent discovery of CITF1 in the PI's lab. CITF1 is a member of the bHLH family of TFs that enables A. thaliana to survive copper deficiency. Preliminary evidence indicates that CITF1 interacts with the SPL7-pathway. Disrupting this interaction causes seedling lethality and pollen sterility. The sites of copper action in anthers and pollen, and the role played by SPL7- CITF1 in pollen development will be characterized through the analysis of mutant lines grown under different copper levels. Synchrotron X-ray fluorescent microscopy will be used to image (2D & 3D) copper distribution during pollen development. In-air scanning electron microscopy and histological analyses will be used to characterize copper-level effects on the anatomy and morphology of control and mutant lines. Targeted chromatin-immunoprecipitation and functional genetic assays will identify direct upstream regulators of CITF1. Global expression profiling coupled with computational co-expression network analyses will reveal likely downstream copper-responsive targets of SPL7 and CITF1, the hierarchy of regulatory components and their relationship to copper uptake, and organ partitioning and delivery. The long-term goals are to understand the regulatory and signaling networks underlying copper homeostasis, and to apply this knowledge to produce cultivars adapted to soils with low copper availability.