Effects of low-voltage electrostatic field on post-harvest sugar metabolism and stress resistance in sweet corn

Abstract

Low-voltage electrostatic field (LVEF) can significantly extend the shelf-life of fruits and vegetables, but its specific action mechanism remains unclear. This study investigated the effects of LVEF on sugar metabolism and associated pathways in post-harvest sweet corn. Compared with the control group, sweet corn stored for 8 days under a 1 kV electrostatic field exhibited a 15 % slower decline in soluble solids, an 8 % reduction in weight loss, and a 23 % slower increase in hardness. Meanwhile, the contents of soluble sugars, fructose, sucrose, and D-glucose increased by 2.15-, 1.90-, 1.85-, and 1.46-fold, respectively. LVEF maintained high sucrose levels by upregulating key sucrose synthesis genes—sucrose-phosphate synthase (SPS) and sucrose synthase (SUS)—while downregulating the glycolysis-related gene ATP-dependent 6-phosphofructokinase (pfkA), thereby inhibiting glucose degradation. Furthermore, LVEF suppressed the expression of genes involved in pectin and lignin biosynthesis, such as UDP-glucose-4-epimerase (USP) and cinnamoyl-CoA reductase (CCR), while enhancing the expression of cellulose-degrading enzyme genes, contributing to improved texture retention. LVEF also induced the upregulation of stress-resistance genes including glutathione S-transferase (GST-X1) and DNA-binding WRKY (WRKY), which helped reduce spoilage rates. In addition, LVEF significantly influenced the accumulation of eight key differential metabolites, such as 1-O-caffeoyl-β-D-glucose and 6-O-p-coumaroyl-β-D-glucose, and helped maintain levels of sugars, alkaloids, and phenolic acids. These findings provide valuable insights into how LVEF treatment affects sugar metabolism and storage quality in sweet corn