Multifunctional Zea mays GLUTAREDOXIN S17 acts as a macromolecular regulator to improve drought resilience in field-grown maize

Drought, a major abiotic stress causing global crop yield losses, necessitates the development of resilient cultivars for sustainable agriculture. Glutaredoxins (GRXs) are key regulators of cellular redox homeostasis; however, their functional roles in crop plants remain largely unexplored. In this study, we develop transgenic maize (Zea mays) hybrid lines with significantly increased productivity under drought field conditions via integration of maize GRX genes. ZmGRXS17.1 and ZmGRXS17.2 exhibited a high degree of amino acid sequence similarity, and their transcript levels were upregulated in response to drought stress. In maize hybrid lines expressing ZmGRXS17.1 or ZmGRXS17.2, osmotic and drought stress tolerance were markedly increased. Under drought conditions, abscisic acid-mediated stomatal closure was markedly reinforced in these transgenic lines, accompanied by fine-tuned modulation of gene expression networks and a pronounced attenuation of drought-induced reactive oxygen species accumulation. Interestingly, ZmGRXS17.1 and ZmGRXS17.2 dramatically induced the expression of both the transcription factor ZmNAC111 and the pyrophosphatase ZmVPP1, which function as key synergistic positive regulators of drought tolerance in maize. Moreover, field experiments revealed that constitutive expression of these genes did not alter agronomic traits under non-drought condition, while stress resilience and grain yield were significantly enhanced in field-grown ZmGRXS17.1- and ZmGRXS17.2-expressing maize lines compared to wild-type plants under drought stress condition. Taken together, these findings show that maize plants overexpressing ZmGRXS17.1 or ZmGRXS17.2 exhibit increased resilience and yield under water-deficit conditions by promoting stomatal closure, drought-responsive gene expression, and redox homeostasis, thereby offering a practical strategy to increase crop production under drought conditions.