High-throughput Screening of EMS Mutagenized Maize for Altered Starch Digestibility

Carbohydrate research increasingly is focused on changing the biochemical nature of starch to create more efficient substrates for biofuel production; parallel work is aimed at healthier foods for human consumption. A key factor in both of these efforts is the rate at which starch is digested by amylases. Starch digestibility is influenced heavily by genetically controlled factors including starch granular and molecular structure and composition. Maize mutant varieties with increased starch digestibility would help to make more cost-efficient biofuels. To identify such mutants among segregating families of ethyl methane sulfonate-mutagenized maize, we developed a miniaturized, high-throughput single kernel preparation and starch digestion assay that can process over 500 samples per week. In a preliminary screen of 480 families, we have identified 62 mutants with faster rates of digestion as compared to wild type and, in the same screen, an additional 53 lines with slower rates of digestion, thus tremendous potential health benefits. These mutants can be used for detailed structural analysis of starch and flour physical and chemical properties, factors that interact with starch in the cell and analysis of an apparently large number of genes that can impact rates of starch digestion.