Abstract
INTRODUCTION: MeJA enhances Cd stress resistance and reduces Cd accumulation in wheat (Triticum aestivum L.). Our previous study demonstrated that exogenous MeJA regulated wheat responses to Cd stress in a concentration-dependent manner. Building on this, the present study investigated the effects of MeJA spraying on grain weight and starch physicochemical properties in wheat under Cd stress. METHODS: Wheat plants were exposed to different soil Cd concentrations (0, 5, 50 mg/kg) and treated with foliar sprays of MeJA at varying concentrations (0, 1 and 10 µM). RESULTS: Cd stress significantly reduced grain weight, inhibited starch synthesis, and impaired starch physicochemical properties by decreasing crystallinity, gelatinization enthalpy, and freeze-thaw stability. In contrast, low-concentration MeJA (1 µM) significantly increased thousand-grain weight, total starch content, and B-type starch granule content, while improving starch crystalline structure, thermal stability, and functional properties, thereby alleviating Cd-induced damage. Genotypic variation revealed a MeJA-mediated trade-off between stress defense and developmental metabolism, with the Cd-tolerant cultivar exhibiting a more efficient jasmonate signaling and metabolic compensation mechanism. DISCUSSION: This study extends previous physiological findings to the starch quality level and provides new mechanistic insight into MeJA-mediated regulation of grain quality and stress adaptation in wheat grown under Cd-contaminated conditions.