Integrating Signals in Iron Homeostasis

铁常常限制植物生长和农业产量。此外，超过20亿人缺铁，因为他们的植物性饮食不是铁的丰富来源，使缺铁成为当今世界最普遍的营养问题。显然，无论是从改善植物生长和作物产量的角度，还是从改善人类营养的角度来看，了解植物中的铁代谢都是至关重要的。尽管在追踪铁如何在植物中移动方面取得了进展，但科学家们仍然不知道植物是如何整合铁供应和光照条件的信息的。这个项目将有助于解释一种名为URI的蛋白质是如何接收并传递有关细胞铁状态和光质量的信息的。与新汉普郡科学院合作，将为6-12年级的学生提供研究经验，这些经验将提高他们对植物所做的一切的欣赏，并教他们如何利用植物的力量，以确保长期的可持续性和健康。NHAS为来自NH和VT的广泛地理部分的学生提供暑期和课外以发现为基础的科学研究计划。他们的外展覆盖了农村地区，那里的学生通常很少有机会体验真正的科学研究。更广泛的影响还将包括培训下一代科学家。来自几个不同指导项目的本科生将参与这项拟议的工作。铁是植物必不可少的营养物质，但太多的铁可能是有毒的。因此，植物只在需要时才吸收铁。必需的bHLH转录因子URI/bHLH121是启动缺铁反应所必需的。一种磷酸化形式的URI在缺铁情况下积累，与亚组bHLH IVC转录因子形成异二聚体，并诱导另一类转录因子Ib亚组bHLH的转录。这些Ib bHLH依次与FIT/bHLH29异源二聚体，并驱动编码铁转运蛋白IRT1和铁络合还原酶FRO2的基因的转录，以增加铁的摄取。尽管控制土壤铁吸收的机制现在已经相对清楚，但关于URI如何整合有关铁供应和光照条件的信息，人们知之甚少。光是URI磷酸化所必需的，这表明光调节的激酶参与其中。基因实验的目的是确定URI磷酸化是红光还是蓝光反应，以及光调节激酶(PPK)家族的成员是否参与其中。实验还将解决缺铁途径中需要光信息的第二个点，即诱导Fit转录因子。长期目标是了解负责在整个植物水平上协调应对缺铁的整个基因网络。这样的理解将转化为在植物生产力和营养含量方面可持续提高作物产量的努力。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Iron often limits plant growth and agricultural yield. Furthermore, more than 2 billion people are iron deficient because their plant-based diets are not a rich source of iron, making iron deficiency the most prevalent nutritional problem in the world today. Clearly, understanding iron metabolism in plants is crucial, both from the point of view of improving plant growth and crop yields, as well as improving human nutrition. Despite progress in tracing how iron moves throughout the plant, scientists still do not understand how plants integrate information about iron supply and light conditions. This project will help to explain how a protein called URI receives and then conveys information about both the iron status of a cell and light quality. In partnership with the New Hampshire Academy of Science, students in grades 6-12 will be offered research experiences that will raise their appreciation for all that plants do and teach them how to leverage the power of plants to ensure long term sustainability and health. NHAS runs summer and after school discovery-based scientific research programs for students from a wide geographic section of NH and VT. Their outreach covers rural areas where students generally have few opportunities to experience authentic scientific research. Broader impacts will also include training the next generation of scientists. Undergraduates from several different mentoring programs will participate in the proposed work.Iron is an essential nutrient for plants, yet too much iron can be toxic. Therefore, plants only take up iron when needed. The essential bHLH transcription factor, URI/bHLH121, is required for mounting the iron deficiency response. A phosphorylated form of URI accumulates under iron deficiency, forms heterodimers with subgroup bHLH IVc transcription factors and induces transcription of another class of transcription factors, the sub-group Ib bHLH. These Ib bHLH in turn heterodimerize with FIT/bHLH29, and drive the transcription of the genes encoding the iron transporter IRT1 and the ferric chelate reductase FRO2, to increase iron uptake. Although the mechanisms controlling iron uptake from the soil are now relatively well understood, little is known about how URI may integrate information about iron supply and light conditions. Light is required for URI phosphorylation, suggesting that a light-regulated kinase is involved. Genetic experiments were designed to determine whether URI phosphorylation is a red light or blue light response, and whether members of the photoregulatory kinase (PPK) family are involved. Experiments will also address a second point in the iron deficiency pathway where light information is required, namely the induction of the FIT transcription factor. The long-term goal is to understand the entire network of genes responsible for orchestrating a coordinated response to iron deficiency at the whole plant level. Such an understanding will transform efforts towards sustainable improvements of crop yields, in terms of plant productivity and nutrient content.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.