NSF Award
0412091
The green revolution of the 1950s-1970s heralded large increases in crop yields largely through the use of nitrogen fertilizers. However, nitrogen fertilization is expensive economically and environmentally. Nitrogen fertilization is one of the highest on-farm costs in agriculture. A significant amount of fossil fuel is used to produce these fertilizers at an ever-increasing cost. In addition, much of the fixed nitrogen applied to soils is never taken up by the plants and leaches into ground water, contaminating much of the drinking water in many rural areas of the United States. To eliminate the need for nitrogen fertilization, bacteria need to be discovered that can provide fixed nitrogen to important grasses in agriculture such as wheat and corn. In recent years, several nitrogen-fixing bacteria have been isolated from lines of grasses that require very little nitrogen for growth. Nitrogen-fixing bacteria have been studied for over 100 years and they capture N2 from the atmosphere and convert it to a form of nitrogen that can be used by plants.<br/><br/>One of the bacteria isolated in the Triplett laboratory has been studied extensively and is capable of invading the interior of many plants without causing disease symptoms. This strain probably enters plants in such high numbers because it either eludes, or fails to induce, plant defense mechanisms that would prevent other bacteria from entering the plant. In fact, this strain, Klebsiella pneumoniae 342 (Kp342), actually enhances plant growth. In wheat (but not other grasses), Kp342 actually provides fixed nitrogen to plants and can relieve N-deficiency symptoms when cultured in the absence of any nitrogen fertilizer. More basic knowledge of Kp342's metabolism and regulatory circuits is needed in order to further improve this strain's ability to provide nitrogen to wheat, corn, rice, and other grasses. The most thorough and effective way to learn more about this strain is through determining the entire genome sequence of this organism. Once the sequence is known, it will be examined carefully to discover every gene in this organism. The Institute for Genomic Research and the University of Florida will perform complete genome sequencing of Kp342. With the discovery of every gene in Kp342 will come a significant effort in training and outreach. A summer workshop will be established for undergraduate and graduate students at the University of Florida where students will learn to compare the genomes of nitrogen fixing bacteria, bacterial endophytes, and Klebsiella strains. A significant outreach effort will be done to develop a national curriculum in genome science that will be available to the youth in America who are interested in science and technology.
