Work

Starch synthesis enzymes mediate oxidative stress-induced grain quality decline in rice under saline-alkali stress

Year: 2026

Type: article

Abstract: Introduction: Soil salinization is a major constraint on rice production and grain quality, yet the physiological mechanisms linking saline-alkali stress to grain quality deterioration remain poorly understood. Methods: This study investigated the physiological cascade through which saline-alkali stress deteriorates grain quality, using four rice genotypes of contrasting salt tolerance as physiological models. Plants were grown under control and saline-alkali stress (3.0‰ soil salt) conditions, and grain quality, starch enzymes, oxidative stress markers, and starch structure were analyzed at key developmental stages. Results: Saline-alkali stress significantly inhibited AGPase, GBSS, SSS, and SBE activities across grain filling (15-45 DAP), with AGPase, SSS, and SBE showing the most pronounced suppression at 15 DAP, while GBSS exhibited a milder, genotype-dependent response. MDA accumulated markedly with genotype-dependent SOD/CAT imbalances. Correlation network analysis identified AGPase, SSS, and SBE as central hub nodes. XRD revealed reduced crystallinity; SEM showed altered granule morphology. Amylose increased while total starch decreased, reflecting carbon flux rerouting. Discussion: These findings delineate a physiological cascade of oxidative stress leading to enzyme inhibition, carbon-nitrogen imbalance, crystalline disruption, and quality deterioration, providing targets for genetic improvement. Future studies using ROS scavengers or gene editing are needed to establish causality.

Source: Frontiers in Plant Science

DOI: 10.3389/fpls.2026.1955582