Identification and analysis of glutaredoxin genes in Amaranthus palmeri reveal roles in abiotic stress responses.

Amaranthus palmeri is a destructive invasive weed that exhibits strong resistance to various abiotic stresses. However, the molecular mechanisms underlying this stress tolerance remain largely unknown. In this study, we identified 12 ApGRX family members and performed systematic characterization using bioinformatics and functional validation approaches. Transcriptional profiling revealed that ApGRX genes mediate the entire stress response process under exposure to NaCl, drought, H2O2, and glufosinate ammonium. Two key proteins, ApGRX2 and ApGRX3, were experimentally verified to localize at the plasma membrane. Under stress conditions, NBT and DAB staining showed that leaves transiently overexpressing ApGRX2 or ApGRX3 accumulated less ROS, with reduced malondialdehyde (MDA) content and increased catalase (CAT) and superoxide dismutase (SOD) activities. Heterologous expression of ApGRX2 and ApGRX3 improved yeast growth under salt and osmotic treatment conditions. This study reveals the basic regulatory roles of ApGRX proteins in the stress adaptation of A. palmeri. These findings provide a foundational framework for understanding GRX-mediated redox regulation in the stress adaptation of A. palmeri and offer candidate gene resources for future functional studies.