Current models for starch synthesis and the sugary enhancer 1 (se1) mutation in Zea maysi

Among the desirable quality traits essential for commercial production of fresh or processed sweet corn, kernel sugar content is universally important. In sweet corn genotypes the primary kernel sugar is sucrose, which is elevated at the expense of starch, particularly amylopectin. Sweet corn mutations have been traditionally divided into two classes. Generally speaking, class one mutations affect cytosolic reactions early in the process of starch synthesis, before starch is synthesized, and class two mutations affect reactions within the amyloplast directly involving starch granule assembly. Two widely used but previously unclassified mutations are sugary1 (su1) and sugary enhancerl (se1). The se1 gene is a recessive modifier of se1; therefore, both genes require mutual discussion. This review provides current information about the si1 and se1 maize endosperm mutations and describes evidence further supporting previous suggestions that they fit criteria for categorization as class two mutants [Science 151 (1966) 341]. Information on the genetics and phenotype of se1 will be summarized and the hypothesized role of the sel gene product discussed within the context of current models for starch synthesis in Zea mays L. (C) 2004 Elsevier SAS. All rights reserved.