MCA: Interactions between density dependence and environmental stress in plant-microbial symbioses

就像人类的身体内外都有细菌一样，植物的组织内部和表面也有细菌。这些细菌有些对植物有益，有些是致病的。然而，植物不能像人类那样移动，所以致病菌有时会在成熟的植物周围积聚，这可能对幼苗有害。此外，可能还有环境梯度，如空气温度或盐度，会改变病原体的积累方式。本项目利用墨西哥湾和大西洋沿岸作为风暴屏障的两种淡水沼泽树种，探索植物病原体积累与盐度梯度之间的相互作用。我们将测试关于植物病原体和盐度的假设，我们将把有益细菌添加到植物中，这些植物生长在另一种基质中，即回收中心的碎玻璃，用于海岸修复。更广泛的影响包括参与社区组织，并为当地的玻璃回收初创企业提供数据。当土壤中的微生物聚集在成熟树木周围，为同一物种的幼苗提供负生长环境时，就会发生负反馈。这种现象已经在许多种栖息地中出现，但人们对环境中增加的压力如何与负反馈相互作用知之甚少。随着与气候相关的压力因素在许多栖息地中不断增加，这种知识差距成为一个问题。我们在海平面上升和飓风强度的背景下解决了这一知识差距，使用淡水沼泽树作为我们的重点物种。笼统地说，我们会问：负反馈和盐度压力增加之间的关系是什么？植物-共生体相互作用的研究系统有促进或干扰的可能，这些结果可能随着胁迫而改变。两个温室实验将测试沿盐度梯度和破碎的回收玻璃的负密度依赖的影响。我们预测在低胁迫条件下，幼苗在异种土壤中生长有利，而在高胁迫条件下，幼苗在同种土壤中生长有利。由于在许多栖息地都观察到负反馈，我们的研究结果可能对我们对与压力相关的生态过程的理解产生重大影响。为了产生更广泛的影响，我们正在与社区组织合作，并向当地一家玻璃回收初创企业提供数据。密西西比三角洲为美国提供了数十亿美元的经济价值。使用原本会被填埋的回收材料，将增加补充沼泽的能力，并在越来越盐碱化的地区恢复水文。该项目由人口与社区生态计划和促进竞争研究的既定计划（EPSCoR）共同资助。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知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Just as humans live with bacteria on the inside and outside of their bodies, plants have bacteria inside their tissues and on their surfaces. Some of these bacteria are beneficial and some are pathogenic (cause disease) to the plants. Plants cannot move as much as humans, however, so pathogenic bacteria can sometimes accumulate around mature plants and this might be detrimental to young seedlings. In addition, there might be environmental gradients, like air temperature or salinity, that change how the pathogens build up. This project explores the interplay between plant-pathogen accumulation and salinity gradients, using two freshwater swamp tree species that act as a storm barrier along the Gulf of Mexico and Atlantic coasts. We will test hypotheses about plant pathogens and salinity, and we will add beneficial bacteria to plants that are growing in an alternative substrate, crushed glass from recycle centers, for coastal restoration. Broader impacts include engaging community organizations and providing data to a local start-up for glass recycling.Negative feedback occurs when microorganisms in the soil accumulate around a mature tree and provide a negative growth environment for young seedlings of the same species. This phenomenon has been shown across many kinds of habitats, but much less is known about how increased stress from the environment interacts with negative feedback. This knowledge gap is a problem as climate-related stressors are increasing in many habitats. We address this knowledge gap in the context of sea level rise and hurricane intensity, using freshwater swamp trees as our focal species. Broadly we ask: what is the relationship between negative feedback and increasing salinity stress? There is a possibility of both facilitation or interference in our study system of plant-symbiont interactions, and these outcomes may change with stress. Two greenhouse experiments will test the effects of negative density dependence along a salinity gradient and in crushed, recycled glass. We predict that seedlings will benefit from growing in heterospecific soil when stress is low but will benefit from growing in conspecific soil when stress is high. Because negative feedback is observed in so many habitats, our research findings may have a large impact on our understanding of ecological processes related to stress. For broader impacts, we are engaging community organizations and providing data to a local start-up for glass recycling. The Mississippi Delta provides billions in economic value for the US. Using recycled materials that would otherwise go to a landfill, will increase the ability to replenish swamps and restore hydrology in areas that are becoming more and more saline.This project is jointly funded by the Population and Community Ecology program and the Established Program to Stimulate Competitive Research (EPSCoR).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.