Nucleoredoxin 1 in Wheat: Genomic Analysis and Demonstration of Its Role in Redox Homeostasis and Stress Resilience.

Nucleoredoxin 1 (NRX1), a member of the redoxin superfamily, plays a critical role in maintaining redox homeostasis and enhancing stress tolerance in plants. We employed integrated in silico analyses and CRISPR-Cas9-based genome editing to functionally characterize NRX1 in Triticum aestivum (wheat) responding to salinity and infection by Puccinia striiformis. We identified five NRX1 proteins coded by three homeologs, with each containing conserved thioredoxin-like domains and a Cys-rich C-terminal region. Sequence analysis predicted cytosolic and chloroplast localization, and promoter analysis predicted interaction with numerous cis-regulatory elements responsive to stress and hormones, including ABRE, MeJARE, and LTRE motifs. Expression profiling revealed significant upregulation of NRX1 in response to both salinity and P. striiformis infection. Protein-protein interaction analysis via STRING predicted strong co-expression of NRX1 with 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR) and thioredoxins, implicating NRX1 in regulating the methylerythritol phosphate pathway-crucial for isoprenoid biosynthesis and reactive oxygen species detoxification. CRISPR-Cas9-mediated knockout lines nrx1-b and nrx1-bd showed increased susceptibility of mutant plants to salinity and stripe rust infection. The total chlorophyll content was significantly reduced, and higher accumulation of malondialdehyde and decreased activities of catalase, superoxide dismutase, peroxidase, and ascorbate peroxidase were recorded compared to wild type (BW208) wheat. These results indicate NRX1 is an important regulator of redox signaling and stress adaptation in wheat, likely functioning through modulation of antioxidant enzymes and isoprenoid pathway intermediates. This study provides mechanistic insights into wheat stress biology and highlights NRX1 as a valuable molecular target for developing stress-resilient wheat cultivars under climate change scenarios.