The researchers studied two types of high amylose maize starch to see how the genes related to starch production affect the structure of the starch molecules. They found that the high amylose starches had shorter amylose chains and longer amylopectin chains compared to normal maize starch. The high amylose starches also had more long amylopectin chains. The genes that control branching and debranching of starch molecules were expressed differently in the high amylose starches, leading to an increase in amylose content. Additionally, a specific gene was associated with shorter amylose chain lengths in the high amylose starches.