DISSERTATION RESEARCH: The role of rhizobial mutualisms in the establishment and colonization of non-native acacia species in California

含有固氮菌的植物，如紫花苜蓿和大豆，是土壤肥力的重要自然来源。这些细菌还会促进寄主植物的生长，一些带有固氮菌的野生植物会变得高度入侵；当人类把它们带到一个新的地区时，它们会传播并排挤其他物种。该项目将检验这样一种假设，即这些被引入的植物的侵入性取决于它们在新的栖息地与固氮菌形成关系的能力，或者取决于它们自己的固氮菌是否与它们一起被引入。研究人员将对从澳大利亚引进加州的相思树属乔木和灌木进行比较。这些物种中的一些已经广泛传播，而另一些则没有成为入侵物种。该项目将使用分子遗传技术来区分本地的加州固氮细菌和引进的澳大利亚细菌，并测试入侵程度更高的物种是否更能容纳加州细菌，更多的澳大利亚细菌，还是更少依赖固氮细菌生长。澳大利亚相思在美国和世界各地已经变得入侵，威胁到农田和受保护关注的地区，并减少了供水。该项目的成果将帮助管理人员控制这些树和其他固氮、入侵植物的蔓延。研究人员将积极向旧金山和圣地亚哥附近的栖息地恢复项目传播研究成果。该项目还将培训一名博士生和两名本科生，并为路易斯安那州的K-12学生制作演示文稿。

Plants that harbor nitrogen-fixing bacteria, such as alfalfa and soybean, are an important natural source of soil fertility. The bacteria also increase the growth of their host plants, and some wild plants with N-fixing bacteria become highly invasive; they spread and crowd out other species when introduced by humans to a new region. This project will test the hypothesis that the invasiveness of these introduced plants is determined by their ability to form relationships with the N-fixing bacteria in their new habitats, or by whether their own N-fixing bacteria have been introduced along with them. Researchers will compare the species of trees and shrubs in the genus Acacia that have been introduced to California from Australia. Some of these species have spread widely, while others have not become invasive. The project will use molecular genetic techniques to distinguish native, Californian, N-fixing bacteria from introduced, Australian bacteria, and test whether the more invasive species are more able to harbor Californian bacteria, have more Australian bacteria, or depend less upon N-fixing bacteria for their own growth.Australian Acacias have become invasive in the U.S. and around the world, threatening agricultural lands and areas of conservation concern, and reducing water supplies. Results from this project will help managers control the spread of these trees and of other N-fixing, invasive plants. Researchers will actively disseminate results to habitat restoration programs near San Francisco and San Diego. The project will also train a Ph.D. student and two undergraduates and develop presentations for K-12 students in Louisiana.