To Elucidate N-acylethanolamine Metabolic Pathway And Its Role In Mediating Dehydration Stress Tolerance In Physcomitrella Patens

自然生长环境的干扰会引起植物的应激反应，使它们能够抵抗、容忍或适应这些变化。这种应激反应通常涉及代谢信号网络的激活。本项目的主要目的是研究苔藓植物中一种独特的脂类代谢物--花安德胺的代谢及其在苔藓植物脱水耐受性发展中的作用。花安德胺通常存在于哺乳动物中，尽管它存在于苔藓中，但在高等植物中尚未见报道。在哺乳动物中，这种化合物参与神经元信号传递，这增加了它在苔藓中也作为信号的可能性。苔藓植物对许多压力具有天然的耐受性，这项研究有望确定苔藓植物中存在的独特脂肪是否在苔藓植物表现出的更强的脱水耐受性中发挥作用。这项研究的发现将揭示对脂类介导的生物反应的新的功能和进化见解，这可能在植物中广泛适用。这样的见解可能会导致制定未来培育耐受压力作物的战略，帮助在干旱期间和边际土地上维持粮食生产。该项目还为东田纳西州立大学的研究生和本科生以及副研究员提供了亟需的研究机会，该大学主要是一所本科院校，吸引了许多来自阿巴拉契亚地区的地区性第一代学生。N-酰基乙醇胺(NAE)是一类广泛分布于真核生物中的脂肪酸衍生物。在各种类型的NAE中，Anandamide被认为与大麻素受体结合，并在哺乳动物的各种生理过程中发挥神经调节剂的作用。最近，在苔藓植物中发现了一种20碳的多不饱和omega-6脂肪酸乙醇胺(NAE 20：4)，但在高等植物中没有发现。这一发现开启了一种可能性，即早期陆地植物中的NAE可能发挥着与动物相似的独特作用，并且超出了开花植物的已知范围。长期以来，苔藓植物中非常规脂质的存在一直被认为是苔藓成功从水过渡到陆地的关键，因为脂质可能赋予它们天然的能力，使它们能够抵抗高温，耐受渗透、盐胁迫和脱水。因此，推测苔藓在进化过程中可能保留了独特的NAE代谢物，如花青胺，以及它们介导逆境耐受的机制。为了解决这一前提，本论文将利用Physcomitrella patens实现以下三个主要目标：1)NAE代谢途径的生化和分子特征；2)测定NAE代谢产物的组成及其对发育的影响；3)阐明NAE在脱落酸介导的脱水耐受中的生理作用。研究将利用在其他真核系统中的发现，包括调节NAE代谢途径的酶和脂谱技术。该项目的长期目标是阐明苔藓维持对非生物胁迫的耐受性的机制，维管束植物可能已经改变或失去了这种耐受性，并揭示了对植物中脂类介导的生物反应的新的功能和进化见解。

Disturbance in the natural growth habitat causes stress responses in plants that enable them to resist, tolerate or adapt to these changes. Such stress responses often involve activation of a network of metabolic signals. The main objective of this project is to study the metabolism and role of a unique lipid metabolite called anandamide in the development of dehydration tolerance in moss plants. Anandamide typically occurs in mammals, and has not been reported in higher plants, despite its occurrence in mosses. In mammals, this compound is involved in neuronal signaling, raising the possibility that it also acts as a signal in mosses. Moss plants are naturally tolerant to many stresses and this study is expected to determine if the unique lipids present in mosses, but absent in higher plants, play a role in the greater dehydration tolerance shown by mosses. The findings from this study will reveal novel functional and evolutionary insights into lipid-mediated biological responses that may be widely applicable in plants. Such insights may lead to development of strategies to generate stress tolerant crop plants in the future, helping to maintain food production during droughts and on marginal lands. The project also offers much needed research opportunities to graduate and undergraduate students and a research associate at East Tennessee State University, which is a primarily undergraduate institution that attracts many regional, first-generation students from the Appalachian region.N-acylethanolamines (NAEs) are a class of fatty acid derivatives that are widely distributed among eukaryotes. Among the various types of NAEs, anandamide is known to bind to cannabinoid receptors and acts as a neuromodulator for a variety of physiological processes in mammals. Recently, anandamide, a 20-carbon, polyunsaturated omega-6 fatty acid ethanolamide (NAE 20:4) was identified in moss plants but not in higher plants. This discovery has opened the possibility that NAEs in early land plants may play a unique role that is akin to that in animals and beyond what is known in flowering plants. The presence of unconventional lipids in bryophytes has long been considered crucial for their successful transition from water to land because lipids may have imparted them with natural ability to resist high temperatures and tolerate osmotic and salt stresses and dehydration. Therefore, it is hypothesized that mosses may have evolutionarily retained unique NAE metabolites, such as anandamide, and mechanisms by which they mediate stress tolerance. To address this premise, three main objectives will be pursued, using Physcomitrella patens: 1) Biochemically and molecularly characterize the NAE metabolic pathway, 2) Determine NAE metabolite profiles and their effects on development, and 3) Elucidate the physiological role of NAEs in abscisic acid-mediated dehydration tolerance. Studies will take advantage of discoveries made in other eukaryotic systems, including the enzymes that regulate NAE metabolic pathway and lipid-profiling techniques. Long-term goals of the project are to elucidate the mechanisms by which mosses maintain tolerance to abiotic stress, which perhaps may have been altered or lost in vascular plants, and reveal novel functional and evolutionary insights into lipid-mediated biological responses in plants.