Maize <i>sugary enhancer1</i> (<i>se1</i>) is a gene affecting endosperm starch metabolism.

Abstract

<i>sugary enhancer1</i> (<i>se1</i>) is a naturally occurring mutant allele involved in starch metabolism in maize endosperm. It is a recessive modifier of <i>sugary1</i> (<i>su1</i>) and commercially important in modern sweet corn breeding, but its molecular identity and mode of action remain unknown. Here, we developed a pair of near-isogenic lines, W822Gse (<i>su1-ref/su1-ref se1/se1</i>) and W822GSe (<i>su1-ref/su1-ref Se1/Se1</i>), that Mendelize the <i>se1</i> phenotype in an <i>su1-ref</i> background. W822Gse kernels have lower starch and higher water soluble polysaccharide and sugars than W822GSe kernels. Using high-resolution genetic mapping, we found that wild-type <i>Se1</i> is a gene Zm00001d007657 on chromosome 2 and a deletion of this gene causes the <i>se1</i> phenotype. Comparative metabolic profiling of seed tissue between these 2 isolines revealed the remarkable difference in carbohydrate metabolism, with sucrose and maltose highly accumulated in the mutant. <i>Se1</i> is predominantly expressed in the endosperm, with low expression in leaf and root tissues. Differential expression analysis identified genes enriched in both starch biosynthesis and degradation processes, indicating a pleiotropic regulatory effect of <i>se1</i> Repressed expression of <i>Se1 and Su1</i> in RNA interference-mediated transgenic maize validates that deletion of the gene identified as <i>Se1</i> is a true causal gene responsible for the <i>se1</i> phenotype. The findings contribute to our understanding of starch metabolism in cereal crops.