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

由于人口增长、人均作物使用量增加、大气中二氧化碳含量增加以及其他环境问题等多种因素，全球农作物生产面临着巨大压力。一个主要挑战是以经济和环境可持续的方式提高全球作物产量。对于许多作物来说，一个关键的限制因素和最大的单一投入成本是氮（N）。在发展中国家，过高的化肥成本导致产量降低，而大量使用氮肥会造成严重和不可逆转的环境破坏。因此，更好地了解作物如何利用氮将导致可以提高作物生产力的技术，并将显着降低成本，提高各国农民的产量。植物如何感知和吸收氮在一个相互作用的复杂网络中占据着中心节点。这项研究的重点是这个网络的特定节点，以澄清植物如何整合氮水平，以最大限度地提高植物生长。本研究的一个特别目的是分析两个基因的功能，涉及不同但重叠的节点。1)ENOD93家族基因调节植物如何感知氮并传递此信息以协调植物生长和开花时间与养分可用性，这与产量直接相关。在初步研究中，我们发现在不同的植物物种中改变ENOD93基因的活性，包括重要的作物植物如水稻，导致在较低的氮输入下改善植物生长。2)与ENOD93类似，GATA 12基因在不同的氮水平下调节生长，以协调生长性状，如开花时间和生物量生产。确定这些基因是如何单独或共同发挥作用的，将有助于深入了解协调营养吸收与植物生长的更大遗传网络。因此，了解这些基因控制的潜在机制可以揭示创造更好的作物的新的和深刻的方法。研究植物生长复杂性的研究人员普遍认为，在植物如何利用营养物质创造生物量和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，减少负面影响的重要第一步。这项研究的最终成果将是提供知识，从而生产出养活世界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.