Ecology and Evolution of a Novel Symbiont Lineage: The Interaction of Burkholderia Bacteria with Neotropical legumes

Suny At Binghamton, Binghamton NY

Investigators

Abstract

The symbiosis between legume plants and root nodule bacteria (rhizobia) is globally significant both to human welfare and to natural ecosystems, because it converts nitrogen gas to ammonia, which is often a key limiting nutrient for plant productivity. Yet despite more than a century of intensive study, biologists did not discover until 2001 that certain legume plants use nodule bacteria in the genus Burkholderia, which have an extremely distant relationship to all other known rhizobia. This project will analyze strains of Burkholderia from the tropical forest on Barro Colorado Island, Panama to determine which legume plant species use Burkholderia as nodule bacteria. It will also examine whether legume species that associate with Burkholderia in this community also utilize similar Burkholderia strains in other parts of their geographic range. Finally, it will also compare the relative benefits to plants of interacting with Burkholderia vs. other rhizobia. The main value of this project is that it will provide a broader comparative understanding of legume-rhizobial symbioses, by analyzing a group of symbiotic bacteria unknown to biologists until very recently. Many Burkholderia species are important human pathogens or plant pathogens, and at least one legume host of Burkholderia nodule symbionts is a serious invasive weed. Therefore, this research will also provide a better understanding of the basic ecology of this bacterial genus, especially, whether bacterial pathogens may potentially evolve to become beneficial plant symbionts (or vice versa). This information is important for evaluating the impact of this bacterial group on the environment and on human health.