Understanding A Critical Symbiosis: Nitrogen Fixing in Plants

Atmospheric nitrogen is essential to all life, but in this form is inaccessible to all plants and animals. Much of life is limited by naturally occurring “fixation” of nitrogen, that is, rendering this element bioavailable, and this is particularly limiting for human agriculture. Nitrogen-fixing symbioses — the relationships some plants like legumes and their relatives have with nitrogen-fixing bacteria — allow legume crops to grow in poor soils without enough nitrogen to support competing plants. Understanding how this symbiosis works could reduce fertilizer use, reducing the high energy cost of fertilizer production, limiting agricultural runoff, and securing the food supply in arid parts of the globe.

One of the remarkable aspects of this globally important symbiosis is how plants able to commence it are closely clustered relatives in the Tree of Life. Although clustered, some plants within this group have the symbiosis and some don’t. It has long been thought that all plants that are part of this cluster, whether they express the symbiosis or not, share an unknown genetic mechanism that enables this plant-bacterium relationship. Researchers are slowly starting to unravel this mystery, using a combination of genomic tools and data about where these species are found.

In this expedition, we are partnering with the New York Botanical Garden to help unlock biodiversity data in plants with nitrogen-fixing symbioses as captured by museum specimens to understand the symbiosis from the genetic level to ecology. All the specimens you are helping to transcribe will also be used to generate genomic data, in order to help us further understand the underlying basis of this symbiosis. The label data are also important for helping us understand how the environment and geography have shaped this symbiosis. Your contributions will help us build one of the largest biodiversity projects yet attempted to understand the origin of this globally important plant trait.