Rare Earth Elements Induce Drought Tolerance in Dicranopteris pedata from Ion-Adsorbed Rare Earth Mining Area in Southern China

The ion adsorption rare earth (IARE) mining areas in southern China frequently experience severe seasonal drought, posing significant challenges to plant growth. This study investigates the hypothesis that rare earth elements (REEs) present in these mining areas induce drought resistance in Dicranopteris pedata (D. pedata). An experiment was designed with three drought stress intensities (0%, 5%, and 10% PEG6000) and three levels of rare earth element (REE) addition (none, low, and high). After 72 h of drought stress, physiological indices and metabolomic profiles of D. pedata were examined. The results showed that under drought conditions, the REE additions increased the catalase and peroxidase activities of D. pedata by 99.04% and 81.25%, respectively, and the contents of proline, soluble proteins, and soluble sugars by 97.52%, 71.24%, and 61.81%, respectively. Metabolomic analysis revealed up-regulation of lipid and lipid-like molecules, as well as flavonoid metabolism, which contribute to improved drought resistance in D. pedata under stress. Furthermore, REE addition further up-regulated flavonoid and anthocyanin synthesis compared to drought stress alone, enhancing the plant’s resilience to drought. These findings suggest that D. pedata responds to drought stress by modulating enzyme activities, osmoregulatory substances, and metabolic pathways upon REE exposure. This study underscores the dual role of REEs in enhancing both the drought tolerance and enrichment capacity of D. pedata in IARE mining areas, which is crucial for sustaining plant growth amidst drought stress, and provides new ideas for the ecological restoration and sustainable development of IARE mining areas.