Exploring the nexus of Nitrogen and Carbon utilization and its role in plant growth and the transition to reproductive development

由于几个因素，包括人口增长、人均作物使用量增加、大气二氧化碳增加和其他环境问题，全球作物生产面临相当大的压力。一个主要挑战是以经济和环境可持续的方式增加全球作物产量。对许多作物来说，一个关键的限制因素和最大的单一投入成本是氮。在发展中国家，高昂的肥料成本导致产量下降，而大量使用氮肥会造成重大的、不可逆转的环境破坏。因此，更好地了解作物是如何利用氮的，将带来能够提高作物生产力的技术，并将显著降低成本，提高各国农民的产量。植物如何感知和吸收氮在相互作用过程的复杂网络中占据中心节点。本研究着眼于该网络的特定节点，以阐明植物如何整合N水平以最大化植物生长。本研究的一个特别目的是分析两个基因在不同但重叠的节点中所涉及的功能。1) ENOD93家族基因调节植物对氮的感知和传递，协调植物生长和开花时间与养分有效性，与产量直接相关。在初步研究中，我们发现改变不同植物物种（包括水稻等重要作物）中ENOD93基因的活性，可以在低氮输入下改善植物生长。2)与ENOD93相似，GATA12基因在不同氮水平下调控生长，协调开花时间和生物量等生长性状。确定这些基因是如何单独或共同发挥作用的，将有助于了解协调植物生长和营养吸收的更大的遗传网络。因此，了解这些基因控制的潜在机制可以为创造更好的作物带来新的和敏锐的方法。研究植物生长复杂性的研究人员的普遍共识是，在植物如何利用营养物质创造生物量并因此产生产量方面，还有很大的改进空间。提高这一过程的效率是创造更好的作物并减少负面影响的关键第一步。这项研究的最终结果将是提供知识，从而生产出养活世界上大多数人口所需的作物，同时减少对环境的破坏。

Summary for Public Release Worldwide crop production is under considerable stress due to several factors, including population growth, increased crop use per person, increasing atmospheric CO2 and other environmental issues. A major challenge is to increase global crop yields in an economically and environmentally sustainable fashion. A key limiting factor and single largest input cost for many crops is nitrogen (N). Whereas prohibitive fertilizer costs in developing countries leads to lower yields, use of large amounts of N fertilizer causes significant and irreversible environmental damage. Thus, a better understanding of how crops use nitrogen will lead to technology that can enhance crop productivity and would markedly reduce costs and increase yields for farmers of all nations. How plants sense and assimilate N occupies a central node in a complex meshwork of interacting processes. This research focuses on specific nodes of this network to clarify how plants integrate N levels to maximize plant growth. A particular aim of this study is to analyse the functions of two genes involved in distinct yet overlapping nodes. 1) The ENOD93 family genes modulate how plants sense N and transmits this information to coordinate plant growth and flowering time with nutrient availability, which is directly correlated with yield. In preliminary studies, we find that altering activity of ENOD93 genes in different plant species, including important crop plants such as rice, results in improved plant growth with lower N input. 2) Similar to ENOD93, the GATA12 genes regulate growth under different N levels to coordinate growth traits such as flowering time and biomass production. Determining how these genes function, alone or together, will provide insights into the larger genetic network that coordinates nutrient uptake with plant growth. Accordingly, understanding of the underlying mechanisms controlled by these genes could bring to light new and incisive ways to create better crop plants. A general consensus among researchers studying the complexities plant growth is that there is much room for improvement with regard to how plants use nutrients to create biomass and, thus, yield. Improving the efficiency of this process is a vital first step to creating better crops with fewer negative consequences. The ultimate outcome of this research will be to provide knowledge that leads to the production of crop plants needed to feed the majority of the world population with less environmental damage.