The function of lipid flippases in plant growth and thermotolerance

该项目的一个更广泛的影响目标是培育更耐高温的作物。预计气候变化将导致更频繁和更严重的热应激时期，这将大大降低农作物的产量。与此同时，预测表明，全球粮食产量必须增加70%以上，才能养活预计到2057年将增加到100亿的全球人口。为了满足日益增长的食物需求，我们开发对热胁迫条件更耐受的作物是至关重要的（即，新常态）。拟议的项目旨在更好地了解植物如何在热胁迫期间重塑其脂质膜，特别关注一个将脂质翻转穿过膜的酶家族（脂质翻转酶）。研究目标包括设计选定的脂质翻转酶，使其更具活性，并测试这些经过修饰的酶是否可以加快植物重塑其膜以科普温度变化的速度。 这项研究将确定这种“更快的膜重塑”策略是否对热胁迫条件下的植物生长、生育力和种子产量有任何积极影响。如果成功，这项技术可以应用于作物品种，并有可能提高热胁迫条件下的产量，从而在变暖的世界中加强全球粮食安全。此外，该研究将为本科生研究人员团队提供一个场所，以获得植物生物学领域的深入研究经验。长期的科学目标是了解真核细胞中脂质翻转酶的细胞功能，并利用这些知识制定策略，使作物更具气候适应力。在植物中，脂质翻转酶被称为ALA（氨基磷酸-脂质ATP酶，或P4型ATP酶），并且这些酶利用ATP水解来催化特定脂质从膜的一侧翻转到另一侧。拟南芥中几种ALA的基因敲除导致植物对温度变化高度敏感。指导这项研究的中心假设是，脂质翻转酶在应对温度变化的膜快速重塑中起着关键作用。第一个目的是使用结构域交换和位点特异性诱变来识别不同ALA内的重要调控特征。待检验的关键假设是C-末端结构域的变化通过改变ALA的活性、调节、定位或底物特异性赋予特定的细胞功能。第二个目标是使用脂质组学来量化特定脂质的丰度，并确定温度敏感的ala 3突变体在冷热温度应激期间是否存在脂质重塑缺陷。第三个目标是确定在热应激条件下，过度活跃的ALA的表达是否可以改善营养生长或生殖适应性。实际的重点是利用最近获得的知识对C-末端调控领域的ALA开发一种新的策略，以提高作物的耐热性plants.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用该基金会的智力价值和更广泛的影响审查标准。

A broader impact objective of this project is to develop crop plants that are more tolerant to heat stress. Climate change is expected to result in more frequent and severe periods of heat stress that will significantly reduce yields from agricultural crops. Simultaneously, projections indicate that world-wide food production must increase by more than 70% to feed an expected increase in the global human population to 10 billion by 2057. To meet the growing food demands it is critical that we develop crop plants that are more tolerant to heat stress conditions (i.e., the new normal). The proposed project aims to better understand how plants remodel their lipid membranes during heat stress, with a specific focus on a family of enzymes that flip lipids across membranes (lipid flippases). The research goals include engineering selected lipid flippases to be more active and testing whether these modified enzymes can accelerate the rate in which plants remodel their membranes to cope with changing temperatures. The research will determine whether this “faster membrane remodeling” strategy has any positive effect on plant growth, fertility, and seed yield under heat stress conditions. If successful, this technology could be applied to crop species and potentially improve yields under heat-stress conditions, thus strengthening global food-security in a warming world. Additionally, the research will provide a venue for teams of undergraduate student researchers to gain in-depth research experience in the field of plant biology. The long-term scientific goal is to understand the cellular functions of lipid flippases in eukaryotic cells and to use that knowledge to develop strategies to make crop plants more climate resilient. In plants, lipid flippases are referred to as ALAs (Aminophospho-Lipid ATPases, or P4-type ATPases) and these enzymes utilize ATP hydrolysis to catalyze the flipping of specific lipids from one side of the membrane to the other. Genetic knockouts of several ALAs in Arabidopsis result in plants that are hypersensitive to temperature changes. The central hypothesis guiding the research is that lipid flippases play critical roles in the rapid remodeling of membranes in response to changing temperatures. The first aim is to use domain swapping and site specific mutagenesis to identify important regulatory features within different ALAs. A key hypothesis to be tested is that variations in the C-terminal domain confer specific cellular functions, either by changing an ALA’s activity, regulation, localization, or substrate specificity. The second aim is to use lipidomics to quantify the abundance of specific lipids and determine whether a temperature-sensitive ala3 mutant has a defect in lipid remodeling during hot and cold temperature stresses. The third aim will determine whether the expression of a hyperactive ALA can improve vegetative growth or reproductive fitness under heat-stress conditions. The practical focus is to use recently gained knowledge on the C-terminal regulatory domains of ALAs to develop a novel strategy for improving thermotolerance in crop plants.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.