Maize Gene Discovery, Sequencing and Phenotypic Analysis

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A virtual center will be established, comprising 10 investigators at 6 universities (Virginia Walbot, Stanford University; Vicky Chandler, David Galbraith, and Brian Larkins, University of Arizona; Sarah Hake and Mike Freeling, University of California at Berkeley; Robert Schmidt and Laurie Smith, University of California at San Diego; Martin M. Sachs, University of Illinois; and Volker Brendel, Iowa State University). These investigators will identify, sequence, and determine the effects of mutating every gene in maize.Dr. Walbot, the PI, has studied the regulation of a mobile genetic element, the Mu transposon, for many years. Transposons are pieces of DNA that replicate and insert themselves at other sites in the genome. Mu inserts preferentially within genes, which causes mutations. Dr. Walbot has developed a version of Mu, called RescueMu, which will allow the DNA that flanks the insertion site to be cloned in a simple, one-step procedure. This approach allows a very powerful strategy for elucidating gene sequence and function.A population of maize plants will be generated that together contain RescueMu insertions in every maize gene. These plants will be screened for morphological abnormalities. The DNA flanking the inserted RescueMu elements will be isolated and sequenced. Overall, this approach allows maize genes to be identified and sequenced, and the consequence of disrupting their function to be tested. As a second approach to identify genes that are expressed in maize, this project will determine partial and complete sequences for more than 50,000 cDNAs; (cDNAs are DNA copies of mRNAs). The investigators will fabricate microarrays (arrays of immobilized DNAs) which will be used to survey expression of each gene in different maize lines and tissues. Finally, a simple method will be developed to map these genes to the appropriate maize chromosome in a single step. All information and biological materials developed during the project will be made available to the maize community in a timely fashion.Maize is the most important crop plant in the U.S., and is a distant cousin of Arabidopsis. Consequently, many new genes remain to be discovered in maize. It is clear that genes discovered through this project will affect agronomically important traits. The information and experimental tools developed in the course of the project will be valuable to researchers who study not only maize, but rice, sorghum, and other crops. The RescueMu technology that will be developed during this project will likely be transferable to other important model and crop plants.