DISSERTATION RESEARCH: Interactions between microbial mutualists and coninfecting pathogens

植物和动物经常与生活在它们身上和体内的微生物（微生物）接触。这项研究将是确定病毒之间的竞争如何被有益细菌的存在所改变以及病毒感染是否会减少有益细菌对其寄主植物——普通豆（Phaseolus vulgaris）的益处的重要的第一步。这项工作通过提供与农业作物生产有关的数据直接使公众受益，并通过科学教育和宣传间接使公众受益。豆类和其他豆类是世界范围内重要的、高度可持续的膳食蛋白质来源。更好地了解普通豆类中的微生物相互作用，可以为改变疾病流行和提高作物产量的策略提供信息。对这些知识的追求也将为本科生提供各种实践研究经验。最后，研究结果将通过向社区展示，以及为6-12年级学生开发实践学习经验和迷你课程的方式向公众广泛传播。研究人员将研究寄主植物中额外的共生微生物物种的存在如何改变病毒竞争的结果和共感染中的疾病严重程度，以及2)病原体的感染是否会减少寄主从共生微生物那里得到的好处。利用感染普通豆的病毒系统，将研究占据同一宿主的多种病原体之间的生态和进化相互作用。共生菌有可能通过影响宿主的生长和防御资源来改变共生病原体之间的竞争结果。与此同时，病原体可以诱导宿主产生全面的免疫反应，这可能会损害微生物共生菌。如果病原体感染减少了宿主从共生体获得的利益，这可能会破坏这种联系。感染致病病毒和共生固氮细菌（根瘤菌）的普通豆为研究共生病原体与共生菌之间的相互作用提供了一个高度可处理的系统。在有根瘤菌和没有根瘤菌的植物中，将比较两种病原体竞争能力，即寄主浓度内和寄主之间的传播，以评估共生菌的存在是否对一种病原体物种有不同的益处。通过测定植物的免疫应答激素以及根瘤菌的定植和固氮，可以量化病原菌侵染对共生关系生存能力的影响。

Plants and animals are constantly in contact with microbes (microscopic organisms) that live on and inside them. This research will be an important first step in determining how competition between viruses is altered by the presence of beneficial bacteria and whether infection by viruses can reduce benefits from beneficial bacteria to their host plant, the common bean (Phaseolus vulgaris). This work benefits the public both directly by providing data that is relevant to agricultural crop production and indirectly through scientific education and outreach. Beans and other legumes are important, highly sustainable sources of dietary protein worldwide. A better understanding of microbial interactions in common beans can be used to inform strategies that could alter disease prevalence and increase crop yields. The pursuit of this knowledge will also provide a variety of hands-on research experiences for undergraduate students. Finally, the results of the research will be widely disseminated to the public through presentations to the community and the development of hands-on learning experiences and mini-courses for 6-12 grade students. The researchers will examine how the presence of additional mutualist microbial species in a host plant changes the outcome of virus competition and disease severity in coinfections and 2) whether infection by pathogens reduces the benefit that the host receives from mutualists. The ecological and evolutionary interactions between multiple pathogens which occupy the same host will be studied, using a system of viruses infecting the common bean. Mutualists have the potential to alter competitive outcomes between coinfecting pathogens by influencing host resources for growth and defense. At the same time, pathogens can induce a full immune response by the host that can be damaging to microbial mutualists. If pathogen infection reduces the benefit that the host receives from mutualists, this might destabilize the association. Common beans infected with pathogenic viruses and mutualistic nitrogen-fixing bacteria (rhizobia) offer a highly tractable system for studying the interactions between coinfecting pathogens and mutualists. Two measures of pathogen competitive ability, within host concentration and transmission between hosts, will be compared in plants with and without rhizobia to evaluate whether the presence of a mutualist is differentially beneficial to one pathogen species. The impact of pathogen infection on the viability of the mutualism will be quantified by measuring plant immune response hormones as well as rhizobial root colonization and nitrogen fixation.