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

就像人类体内和体外都有细菌一样，植物的组织内和表面都有细菌。这些细菌有些是有益的，有些是植物的致病细菌。然而，植物不能像人类那样移动，所以病原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，如气温或盐度，改变了病原体的形成方式。这个项目探索了植物病原体积累和盐度梯度之间的相互作用，使用了两种淡水沼泽树木，它们充当了墨西哥湾和大西洋海岸的风暴屏障。我们将测试有关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添加有益细菌，这些基质是来自回收中心的碎玻璃，用于海岸恢复。更广泛的影响包括让社区组织参与进来，并为当地的玻璃回收初创企业提供数据。当土壤中的微生物在成熟的树木周围积累并为同一物种的幼树提供负生长环境时，就会出现负反馈。这种现象已经在许多种类的栖息地中表现出来，但关于环境增加的压力如何与负面反馈相互作用，我们知之甚少。这种知识差距是一个问题，因为在许多栖息地，与气候有关的压力源正在增加。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，使用淡水沼泽树作为我们的重点物种。广义地说，我们问：负反馈和不断增加的盐分压力之间有什么关系？在我们的植物-共生体相互作用的研究系统中，既有促进的可能性，也有干扰的可能性，这些结果可能会随着胁迫的变化而改变。两个温室实验将测试盐度梯度和破碎的回收玻璃中负密度依赖的影响。我们预测，当胁迫较低时，幼苗将受益于生长在异种土壤中，但当胁迫较高时，将受益于生长在同种土壤中。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对与压力相关的生态过程的理解产生很大影响。为了更广泛的影响，我们正在与社区组织接触，并向当地一家玻璃回收初创企业提供数据。密西西比河三角洲为美国提供了数十亿美元的经济价值。使用原本会被送到垃圾填埋场的回收材料，将提高在日益盐碱化的地区补充沼泽和恢复水文的能力。该项目由人口和社区生态计划和既定的激励竞争研究计划(EPSCoR)联合资助。该奖项反映了NSF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。

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.