The Maize Gene Discovery project looks for genes in two complementary ways. One method searches for expressed sequence tags or ESTs. These represent genes that are turned "on" in a specific maize tissue at a specific point in time. (Learn more about MGD's EST strategy) http://www.zmdb.iastate.edu/zmdb/EST/index.html

The second method takes advantage of special transposons -- stretches of DNA that insert copies of themselves inside maize genes. The researchers grew grids of maize plants that all contained a specific, engineered transposon tag called RescueMu. The transposon, whose sequence is known and easily traceable, inserts itself in new chromosome locations, but always within a gene. The researchers then find genes by sequencing the DNA on both sides of RescueMu wherever it's found in those many plants. (Learn more about RescueMu gene tagging) http://www.zmdb.iastate.edu/zmdb/library-plate/index.html

Both approaches to gene discovery have been enormously successful. Thus far, the project has found more than 155,000 ESTs. After determining the overlap among these sequences, the ESTs appear to identify more than 31,000 unique genes (learn more about MGD Accomplishments).

The RescueMu strategy has discovered about 5000 genes. At least 3300 of these match known ESTs, indicating that these are indeed genes with active functions in the maize plant. During the final year of the project, the rate of gene discovery using RescueMu will accelerate. (Learn more about MGD Accomplishments).