The BAG proteins are a family of multi-functional co-chaperones. In plants, BAG proteins were found to play roles both in abiotic and biotic stress tolerance. However, the function of Arabidopsis BAG2 remains largely unknown, whereas BAG6 is required for plants’ defense to pathogens, although it remains unknown whether BAG6 is involved in plants’ tolerance to abiotic stresses. Here, we show that both BAG2 and BAG6 are expressed in various tissues and are upregulated by salt, mannitol, and heat treatments and by stress-related hormones including ABA, ethylene, and SA. Germination of bag2, bag6 and bag2 bag6 seeds is less sensitive to ABA compared to the wild type (WT), whereas BAG2 and BAG6 overexpression lines are hypersensitive to ABA. bag2, bag6, and bag2 bag6 plants show higher survival rates than WT in drought treatment but display lower survival rates in heat-stress treatment. Consistently, these mutants showed differential expression of several stress- and ABA-related genes such as RD29A, RD29B, NCED3 and ABI4 compared to the WT. Furthermore, these mutants exhibit lower levels of ROS after drought and ABA treatment but higher ROS accumulation after heat treatment than the WT. These results suggest that BAG2 and BAG6 are negatively involved in drought stress but play a positive role in heat stress in Arabidopsis.

Heavy metal stress is a critical challenge to agricultural productivity, necessitating deeper insights into the molecular mechanisms of metal transport in plants. In this study, we conducted a comprehensive genome-wide characterization of the Natural Resistance-Associated Macrophage Protein (NRAMP) gene family in Arabidopsis thaliana and identified six AtNRAMP genes. Phylogenetic and synteny analyses revealed their distribution into two distinct clades and evolutionary conservation with legumes such as Glycine max and Arachis hypogaea, indicating functional divergence and gene duplication events maintained under purifying selection. Conserved protein motifs and domains, particularly the NRAMP transmembrane domain, highlighted their conserved role in divalent metal ion transport, while cis-regulatory element analysis demonstrated enrichment of stress- and hormone-responsive elements, pointing to tight transcriptional regulation under environmental challenges. Structural modeling further supported the functional conservation of AtNRAMP proteins. Expression profiling showed clear tissue-specific expression under normal conditions and strong, differential regulation in response to cadmium and other heavy metals, as well as to the phytohormone abscisic acid (ABA). Collectively, these results provide foundational insights into the evolutionary relationships, regulatory mechanisms, and stress-responsive expression of the AtNRAMP gene family, offering a framework for future functional studies and potential applications in developing crops with enhanced heavy metal tolerance and improved growth under stress conditions.