Transcriptomic reprogramming underlies melatonin-mediated enhancement of cadmium tolerance and lateral root growth in soybean

Li, Rongrong

JOURNAL OF HAZARDOUS MATERIALS

2026

511

Pu, XJ;Chen, Q

Soil contamination by heavy metals, particularly cadmium (Cd), poses a serious threat to sustainable soybean (Glycine max) production and food safety. Melatonin (MT) has been reported to enhance plant tolerance to abiotic stress; however, the molecular mechanisms underlying MT-mediated Cd tolerance and cultivar-specific responses in soybean remain largely unclear. Here, comparative transcriptome analysis, weighted gene coexpression network analysis (WGCNA) and physio-biochemical assays were integrated to investigate the regulatory mechanisms of MT-mediated Cd tolerance in soybean. Exogenous melatonin (exMT) application significantly reduced Cd accumulation in roots and shoots by 40% and 38%, respectively, while concomitantly enhancing the antioxidant system. Moreover, treatment with 10 mu M exMT markedly improved plant growth, increasing primary root length, stem length, lateral root number, chlorophyll content and fresh weight by 14, 49, 16, 63 and 18%, respectively. WGCNA revealed that Cd stress triggered a core regulatory network involving MYB36, the senescence-related gene SRG1, the peroxidase gene PRX5, the polyamine oxidase gene PPO and the mitochondrial phosphate transporter gene PiC, which collectively contributed to Cd-induced toxicity. In contrast, integrated analyses identified a distinct regulatory module associated with MT-mediated Cd tolerance, including