Determining Stress Tolerance from Promoter to Protein of Glym_NAC1 Transcription Factor in Glycine max

Soybean ( Glycine max ) is a pivotal crop species due to its high protein content and agricultural significance. Although heavy metals play a critical role in the growth and development of plants, their excessive accumulation can lead to toxic effects. In this study, the role of Glym_NAC1 transcription factor against copper (Cu ²⁺ ) stress was investigated. Firstly, the genomic structure of Glym_NAC1 was analyzed and the exon-intron map of 10 different transcripts was constructed. A subsequent analysis of the promoter region identified 24 cis-regulatory elements, the majority of which were found to be associated with abiotic stress. Furthermore, a protein-protein interaction (PPI) analysis revealed that Glym_NAC1 interacts with proteins associated with laccase and lignin degradation. In physiological experiments, 20 µM and 50 µM Cu ²⁺ was applied to Ilksoy and Traksoy soybean cultivars, respectively. It was observed that this stress caused chlorosis, necrosis, and water loss in plants. Relative water content (RWC) and malondialdehyde (MDA) analysis showed that copper stress caused oxidative damage. Gene expression analysis by qRT-PCR revealed that Glym_NAC1 exhibited increased expression in the Ilksoy cultivar in response to copper stress, while the Traksoy cultivar exhibited a divergent adaptation mechanism. This study makes significant contributions to the field of heavy metal tolerance by elucidating the molecular role of Glym_NAC1 in copper stress tolerance. The findings provide a framework for further research on genetic editing studies aimed at developing plant varieties with enhanced stress tolerance.