Nitrogen is crucial for plant growth but plants cannot harness it directly from the atmosphere. In the United States, legume crops such as soybeans and peas rely on nitrogen fertilizers to boost yields; in 2007, 13 million tons of industrially-produced fertilizers were applied.

Sinorhizobiumnodules in alfalfa roots.
(Image from A. Becker & E.G. Biondi, University of Florence)
Soil bacteria such as Sinorhizobiummeliloti have a symbiotic relationship with plant hosts such as alfalfa, providing them with the needed nitrogen. One of the DOE JGI’s 2009 Community Sequencing Program projects focused on sequencing this microbe’s genome in order to learn more about the nitrogen fixation process and how symbiotic relationships are formed.