DISSERTATION RESEARCH: The role of resource mutualisms in plant adaptation to abiotic environments

植物可以通过分散到压力较小的栖息地、适应压力或与其他有助于减轻压力的生物(如微生物)交往来克服环境压力。尽管应对压力的第三种策略很少受到关注，但越来越多的证据表明，它既常见又有效。被称为根瘤菌的土壤细菌的作用就像天然肥料一样，它将大气中的氮素转化为至少一些植物可以利用的形式。作为回报，这些植物为根瘤菌提供能量。这项研究的目的是确定根瘤菌是否有助于植物在极端水分胁迫下生存。这项研究很重要，因为在全球气候变化的情况下，预计世界大部分地区的干旱压力都会增加，而根瘤菌是植物最有可能克服这种压力的方法之一。这具有实际意义。例如，了解植物-根瘤菌的伙伴关系可能有助于减少农业系统中合成肥料的使用或不必要的用水。结果将通过在国家和区域会议上的陈述以及在高中教室和为博物学家和土地管理人员编写的通讯中广泛分享。研究人员还将为高中生创建和发布与高级选修课程(AP)生物学课程相一致的探究性活动。具体地说，这项研究将调查资源互助者如何影响植物对田间土壤水分的适应。利用豆科植物-根瘤菌互惠关系作为模式系统，研究人员旨在扩大对促进局部适应的机制、物种相互作用如何影响局部适应以及适应的潜在特征的理解。将讨论三个具体问题：(1)植物是否在当地适应土壤水分条件？(2)资源互惠者是否有助于植物适应土壤水分？以及，(3)哪些植物特性推动了对潮湿环境与干燥环境的适应？这些问题将通过一套跨越土壤水分不同的多个地点的相互移植实验、操控温室实验和分子分析来解决。

Plants can overcome environmental stress by dispersing to less stressful habitats, adapting to the stress, or associating with other organisms, such as microbes, that help reduce the stress. Although the third strategy of coping with stress has received very little attention, there is increasing evidence that it is both common and effective. Soil bacteria called rhizobia act like natural fertilizer by converting nitrogen in the atmosphere into a form that at least some plants can use. In return, those plants provide energy to the rhizobia. The goal of this study is to determine whether rhizobia help plants survive under extreme water stress. This research is important because increasing drought stress is predicted for much of the world under global climate change and rhizobia are one of the most likely ways that plants may overcome that stress. This has practical implications. For example, understanding the plant-rhizobium partnership may help reduce application of synthetic fertilizers or unnecessary use of water in agriculture systems. Results will be shared broadly through presentations at national and regional meetings as well as in high school classrooms and in newsletters for naturalists and land managers. The researchers will also create and publish inquiry-based activities for high school students that are aligned with the Advanced Placement (AP) biology Curriculum. Specifically, this research will investigate how resource mutualists influence plant adaptation to soil moisture in the field. Using the legume-rhizobia mutualism as a model system, investigators aim to expand understanding of the mechanisms contributing to local adaptation, how species interactions influence local adaptation, and the traits underlying adaptation. Three specific questions will be addressed: (1) Are plants locally adapted to soil moisture conditions? (2) Do resource mutualists contribute to plant adaptation to soil moisture? And, (3) what plant traits drive adaptation to wet vs. dry environments? These questions will be tackled with an integrated set of reciprocal transplant experiments across multiple sites differing in soil moisture, with manipulative greenhouse experiments, and with molecular analyses.