Deciphering components of the nitrogen limitation response in arabidopsis

由于人口的增加、人均作物使用量的增加和环境问题，世界范围内的作物生产将受到相当大的压力。除水分有效性外，氮是作物生产的主要限制因素。为了开发更有效利用氮的作物，我们必须了解基因型在其获取和利用中的作用。因此，了解氮素限制条件下控制氮代谢的信号传导和调控机制至关重要。本课题将重点开展拟南芥的分子遗传学和基因组学研究。首先，我们希望更详细地了解植物是如何感知氮限制的。其次，我们希望瞄准一组转录因子（GNC和CGA-1），我们已经有大量证据表明它们在氮限制下控制碳氮平衡的作用。此外，这些基因的过表达可导致拟南芥和水稻的生长表型增强。本研究确定了拟南芥氮素限制适应性基因（nla）是拟南芥在限氮条件下适应的关键基因。我们将使用多种技术，包括遗传、生化和生理方法来识别对氮限制适应性途径至关重要的其他基因。此外，我们将描述GNC和CGA-1转录因子的靶点，这将使我们进一步了解它们的作用。最后，我们将对拟南芥对限制氮的反应进行代谢组和转录组分析，包括野生型和我们已经开发或将在未来开发的各种突变和过表达系。长期目标是利用这些信息在作物植物中定位基因，以开发在使用较少氮肥的大田条件下产量更好的遗传品系。这反过来又将大大提高作物生产的经济和环境可持续性。

Considerable stress will be placed on world-wide crop production due to an increased human population, an increase in the crops used per person and environmental issues. Besides water availability, nitrogen is the major limiting factor in crop production. To develop crops that can use nitrogen more efficiently, we must understand the role of genotype on its acquisition and use. Therefore, it is essential to understand the role of signaling and regulatory mechanisms that control nitrogen metabolism under nitrogen limitation conditions. In this proposal, the studies will focus on molecular genetic and genomic studies in Arabidopsis. First, we wish to understand in much greater detail how a plant senses nitrogen limitation. Second, we wish to target a set of transcription factors (GNC and CGA-1) for which we have considerable evidence for their role in controlling the carbon-nitrogen balance under nitrogen limitation. Further, over-expression of these genes can lead to an enhanced growth phenotype in Arabidopsis and rice. We identified the nitrogen limitation adaptability (nla) gene as a key component for the adaptation of Arabidopsis plant grown under limited nitrogen conditions. We will use a variety of techniques including genetic, biochemical and physiological approaches to identify additional genes that are essential for the nitrogen limitation adaptability pathway. In addition, we will delineate the targets of GNC and CGA-1 transcription factors that will allow us to further understand their roles. Finally, we will do a metabolome and transcriptome analysis of the response of Arabidopsis to limiting nitrogen both in wild-type and in the various mutant and over-expression lines that we have developed or will develop in the future. The long term goal is to use this information to target genes in crop plants to develop genetic lines that yield better under field conditions where less nitrogen fertilizer is used. This, in turn, would significantly improve both the economic and environmental sustainability of crop production.