Physiological Responses and Transcriptomic Characteristics of Exogenous Trehalose Alleviating Cadmium Toxicity in Maize Seedlings

Abstract

Cadmium (Cd) contamination poses a severe ecological risk to ecosystems. Trehalose (TR) is a non-reducing disaccharide which can mitigate the adverse effects of heavy metals. The physiological responses and transcriptomic characteristics underlying TR-mediated heavy metal tolerance remain unclear in maize. In this study, maize seedlings were exposed to 200 mg L−1 CdCl2·2.5H2O with or without 23 mM exogenous TR for 5 days. By phenotypic observation, although TR supplementation could not fully restore maize growth under Cd stress, it significantly alleviated Cd-induced inhibition, increasing shoot and root dry weight by 33.80% and 36.67%, respectively, compared with Cd treatment alone. Exogenous TR also improved the photosynthesis under Cd stress. Cd stress triggered excessive ROS accumulation and membrane lipid peroxidation, whereas trehalose application alleviated oxidative damage by significantly reducing O2−, H2O2, and MDA contents while further enhancing SOD and CAT activities. Compared with Cd treatment, cell-wall fractionation revealed a 20.53% increase in root cellulose under Cd+TR combined treatment. Further, exogenous TR reduced Cd concentrations in roots and shoots by 19% and 33%, respectively. RNA-seq identified enriched GO categories related to cell communication, signal transduction, amino acid transmembrane transport, and membrane components, suggesting possible involvement of these processes in the TR response. These findings collectively demonstrate that exogenous trehalose enhances maize cadmium tolerance through coordinated physiological responses and transcriptional adjustments.