The objective of this proposal is to elucidate the mechanism(s) underlying the genetic expression of urease in the higher plant, soybean. Dr. Polacco will investigate the expression of an embryo- specific isoenzyme of urease as well as a ubiquitous isoenzyme found in all tissues but at 1/1000th the level of the embryo-specific urease. Dr. Polacco will conduct molecular genetic experiments to analyze mutants defective in the expression of the embryo-specific isoenzyme. The physical and genetic fine structure maps of the locus that encodes this isoenzyme will be correlated. Furthermore, the PI proposes to isolate mutants in the locus encoding the ubiquitous urease. Gene products that encode factors that pleitropically regulate the urease system will also be genetically defined and characterized. This work will provide important information concerning the factors that regulate tissue-specific gene expression during development. In addition, the ability to isolate mutants in the structural loci will lead to a better understanding of the ureases, their processing and assembly.
