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。这些细菌中的一些是有益的，一些是致病的（导致疾病）的植物。然而，植物不能像人类那样移动，因此病原菌有时会在成熟植物周围积累，这可能对幼苗有害。此外，可能存在环境梯度，如空气温度或盐度，改变了病原体的建立方式。该项目探讨了植物病原体积累和盐度梯度之间的相互作用，使用两种淡水沼泽树种，作为风暴屏障沿着墨西哥湾和大西洋海岸。我们将测试关于植物病原体和盐度的假设，我们将向生长在替代基质中的植物中添加有益细菌，这些基质是回收中心的碎玻璃，用于海岸恢复。更广泛的影响包括与社区组织合作，并为当地一家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，并为同一物种的幼苗提供不利的生长环境时，就会产生负面反馈。这种现象在许多栖息地都有表现，但对环境压力的增加如何与负反馈相互作用知之甚少。这种知识差距是一个问题，因为与气候有关的压力因素在许多栖息地都在增加。我们在海平面上升和飓风强度的背景下解决这一知识差距，使用淡水沼泽树木作为我们的焦点物种。广义地说，我们要问：负反馈和盐胁迫增加之间的关系是什么？在我们研究的植物-共生体相互作用系统中，存在促进或干扰的可能性，并且这些结果可能随着胁迫而改变。两个温室实验将测试负密度依赖性的影响沿着盐度梯度和破碎，回收玻璃。我们预测，幼苗将受益于生长在异质性土壤时，压力低，但将受益于生长在同种土壤时，压力高。由于在许多栖息地都观察到负反馈，我们的研究结果可能会对我们理解与压力相关的生态过程产生很大影响。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。使用回收的材料，否则会去垃圾填埋场，该项目由人口与社区生态学计划和刺激竞争研究计划（EPSCoR）共同资助该奖项反映了NSF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.