IntBIO: Coordinating and integrating whole-plant responses to abiotic and biotic stress signals via changes in plasma membrane proteomes

农业生产有赖于在许多不同的环境条件下成功种植农作物。了解植物如何区分和整合来自不同环境胁迫的信号对于提高作物产量很重要，因为这可以帮助避免育种植物，这些植物可能是因为对一种胁迫的耐受性更强，而无意中变得更容易受到其他胁迫的影响。这项研究调查了新发现的植物对细菌病原体的反应之间的相互作用，这种相互作用与植物对低养分可获得性的反应相交并改变了植物的反应，特别是铁，这是植物和人类必不可少的微量营养素。重要的是，数据表明，植物优先考虑对细菌病原体的反应，而不是低养分利用率。这项工作的目标是了解这两个环境信号是如何以及在植物的哪些部分整合的。这一目标将通过聚集一组在铁营养反应、细菌病原体反应、细胞生物学和植物信号转导方面具有专业知识的研究人员来实现，以检查在单个细胞、特定组织以及叶和根之间的交流中发生的变化。单独研究任何一个方面--无论只是一种压力还是只有一种组织类型--只能提供对更大的、综合的过程的部分了解。除了阐明一种以前未知的可以提高作物产量的生物过程外，该项目还将为下一代科学家提供理想的培训环境，因为个人研究人员将在拥有不同专业知识的实验室之间流畅地流动，对复杂的生物系统进行现代、多学科的调查。铁反应转运蛋白1(IRT1)仅定位于根，是土壤中铁吸收的主要途径。质膜上的IRT1蛋白水平与植物的铁状态成反比。如果植物的铁水平低，IRT1蛋白在PM积累以增加铁的吸收；而如果铁水平足够，IRT1蛋白通过内吞去除而减少。研究小组最近发现，当植物受到细菌感染时，IRT1的水平会迅速下降，即使在应该增加IRT1的低铁条件下也是如此。此外，该团队还发现了三个可以改变植物免疫反应的突变体，这些突变体在低铁条件下也大大降低了IRT1的水平。这些结果表明：(A)生物胁迫信号与铁信号整合在一起，(B)生物胁迫信号优先于低铁信号。该项目的目标是确定如何以及在哪里集成这些信号。由于铁感应主要发生在叶片中，未知信号被传递到根以调节IRT1水平，因此这项研究的一个重要方面将是确定生物胁迫信号是否改变了叶片中的铁信号，直接影响根中的IRT1水平，还是在某种信号整合的组合中起作用。这些可能性将通过结合突变体的细胞特异性互补分析以及只用细菌激发子感染树叶或只感染树根来解决。根或叶中转录组和质膜蛋白质组分析的整合将确定根和/或叶中是否有其他铁响应转录本或蛋白质发生变化，潜在地揭示共同调控的转录本/蛋白质的组织特定网络，以及三个突变体是否显示出相似或明显的差异，从而确定突变体在信号途径中的作用(S)。该奖项反映了美国国家科学基金会的法定使命，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。

Agricultural production relies on successfully growing crop plants under many different environmental conditions. Understanding how plants prioritize and integrate signals from diverse environmental stresses is important for improving crop yields because it can help to avoid breeding plants that may be selected for a greater tolerance to one stress while inadvertently becoming more susceptible to others. This research investigates a newly discovered interaction between plant responses to bacterial pathogens that intersects with and modifies the plant’s responses to low nutrient availability, particularly iron, an essential micronutrient for plants and humans. Importantly, the data indicates that the plant prioritizes responses to bacterial pathogens over low nutrient availability. The goal of this work is to understand how and in which parts of the plant these two environmental signals are integrated. This goal will be accomplished by bringing together a team of researchers with expertise in iron nutritional responses, bacterial pathogen responses, cellular biology, and plant signaling, to examine changes that occur in individual cells, in specific tissues, and in communication between leaves and roots. Examining any one aspect alone – whether only one of the stresses or in only one tissue type – would only provide a partial understanding of the larger, integrated process. In addition to elucidating a previously unknown biological process that could improve crop yields, this project will provide an ideal training environment for the next generation of scientists as the individual researchers will move fluidly between laboratories with different expertise to conduct modern, multidisciplinary investigations of a complex biological system. Iron-Responsive Transporter 1 (IRT1) is localized only to roots and is the main path for iron uptake from the soil. IRT1 protein levels at the plasma membrane (PM) are inversely proportional to the iron status of the plant. If the plant’s iron levels are low, IRT1 protein accumulates at the PM to increase iron uptake; whereas if iron levels are sufficient, IRT1 protein decreases by endocytic removal. The research team recently found that when a plant is challenged by a bacterial infection, the levels of IRT1 rapidly decrease, even under low iron conditions that should increase IRT1. In addition, the team has identified three mutants that alter plant immune responses that also have greatly reduced levels of IRT1 under low iron conditions. These results indicate that (a) biotic stress signaling is integrated with iron signaling, and (b) that biotic stress signaling overrides low iron signaling. The goal of this project is to determine how and where these signals are integrated. Because iron sensing occurs primarily in leaves with an unknown signal being transmitted to the roots to regulate IRT1 levels, an important aspect of this research will be to determine if biotic stress signaling alters iron signaling in leaves, directly affects IRT1 levels in roots, or acts in some combination of signal integration. These possibilities will be addressed through a combination of cell-specific complementation assays of the mutants as well as infecting only leaves or only roots with bacterial elicitors. An integration of transcriptomic and PM proteomic analyses in either roots or leaves will determine if other iron-responsive transcripts or proteins are altered in roots and/or leaves, potentially revealing tissue-specific networks of co-regulated transcripts/proteins, as well as revealing whether the three mutants show similar or distinct differences, thus defining where the mutants may function in the signaling pathway(s).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.