Deciphering components of the nitrogen limitation response in arabidopsis

由于人口增加、人均作物使用量增加以及环境问题，世界范围内的农作物生产将受到相当大的压力。除水分供应外，氮素是作物生产的主要限制因素。为了开发能够更有效地利用氮素的作物，我们必须了解基因在氮素获取和利用中的作用。因此，有必要了解在氮素限制条件下控制氮代谢的信号和调控机制的作用。在这项提案中，研究将集中在拟南芥的分子遗传和基因组研究上。首先，我们希望更详细地了解植物是如何感知氮素限制的。其次，我们希望针对一组转录因子(GNC和CGA-1)，对于它们，我们有相当多的证据表明它们在氮限制下控制碳-氮平衡的作用。此外，这些基因的过度表达可以导致拟南芥和水稻生长表型的增强。我们鉴定了氮限适应性(NLA)基因是在有限氮素条件下生长的拟南芥植物适应的关键成分。我们将使用多种技术，包括遗传、生化和生理学方法来识别对氮素限制适应途径至关重要的其他基因。此外，我们还将描述GNC和CGA-1转录因子的靶标，使我们能够进一步了解它们的作用。最后，我们将对拟南芥在野生型和我们已经开发或将在未来开发的各种突变和过度表达系中对限制氮的反应进行代谢组和转录组分析。长期目标是利用这些信息来针对农作物中的基因，开发出在氮肥使用量较少的田间条件下产量更高的遗传系。反过来，这将显著改善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.