Funds are requested to purchase a MALDI-TOF (matrix assisted laser desorption-time of flight) mass spectrometer, that will be operated as a multi-user facility for research at UW-Madison in the area of plant proteomics. Specifically, this instrument will be used by a dozen well established federally funded laboratories on campus performing genomic research in the model higher plant, Arabidopsis thaliana. The mass spectrometer will be operated as part of the UW Biotechnology Center's existing peptide mass spectrometry facility. This instrument will have a dramatic impact on campus basic research in plant genomics, in allowing us to rapidly identify the precise molecular weight of proteins and peptides, as well as their modified forms, and facilitate ongoing studies in the identification of plant gene function. The Arabidopsis genome sequencing project is ca. 50% completed already, and the entire 100 Megabase genome is expected to be completed within the follow two years. Knowledge of the complete sequence allows us to utilize the mass spectrometer in a very time and resource efficient manner and opens new avenues for exploring the molecular basis for plant growth and development.