Cereals, including corn or maize, are the major source of calories for the world human and animal population and, of late, are used as an alternative to petroleum-based fuels. Rising gasoline and food prices are everyday reminders of the importance of cereals. Accordingly, cereal seed yield and mechanisms to increase it are of paramount importance. This project will use genetic, molecular and biochemical approaches to further characterize a genetic variant that appears to enhance corn yield two to three fold. The variant is in a starch biosynthetic enzyme, adenosine diphosphate glucose pyrophosphorylase (AGPase).
AGPase is a composed of two different subunits. A goal of the project is to genetically combine the recently-isolated variant harbored by the small subunit with a previously-isolated large subunit variant to further enhance corn yield. Physiological experiments will be performed to determine whether the extent of yield increase caused by the small subunit variant is subject to growth conditions of the plant. This is the case with the large subunit.
At a more basic level, the relative roles of the two subunits in catalysis are not clear. Molecular approaches will be used to convert the specificity of the enzyme from ATP to UTP. If successful, the exact roles of each subunit can be elucidated.
The broader impacts of these studies are multifaceted. First, the variants arising from this work have had and will continue to have significant impact on cereal yield. Second, Outreach efforts will continue in educating the public about the science behind transgenic plants and their benefit to society. High school students and the lay public are targeted specifically. The project also includes efforts to contribute to the University of Florida's Center for Precollegiate Education and Training Program, which promotes linkage between K-12 schools and members of the UF faculty. Lectures will be presented to K-12 teachers that participate in the program.
Corn (or maize) is a major crop of the United States and the world. Starch is the major component of the corn seed and, in turn, corn yield. Animal life, including humans, is dependent on starch since animals rely primarily on the starch-rich cereal seeds to provide essential calories and nutrients. Starch is also important for the synthesis of various materials used by society and its importance as an environmentally-friendly, renewable replacement of non-renewable, petroleum-based materials is especially critical. Research efforts have focused on increasing the amount of starch produced in the corn seed. Genetic variants of an enzyme which normally limits the amount of starch synthesis have been identified that increase starch production. These variants have been placed into transgenic corn and were shown to be especially useful in hot growing conditions. Hence these variants should be even more useful as global temperatures continue to increase. In addition, this research showed that evolutionary approaches can be used to efficiently and effectively identify those amino acids that play important roles in protein function. Efforts were also directed towards educating the public about the science behind transgenic or GMO plants.
