ABSTRACT Waterlogging represents a significant abiotic limitation to growth and development in soybean plants, causing intense anatomical, physiological, and biochemical changes. Dopamine (DOP) is a biogenic amine with antioxidant properties that has emerged as a promising regulator of plant stress tolerance. This study aimed to evaluate whether exogenous DOP application mitigates the effects of waterlogging in soybean plants by analyzing root and leaf anatomy, stomatal characteristics, nutritional status, photosynthetic performance, antioxidant metabolism, and biomass accumulation. Waterlogging adversely affected leaf and root structures, nutrient contents, gas exchange, and redox homeostasis. However, plants treated with DOP under waterlogging conditions showed anatomical protection in root and leaf tissues, including increased epidermal thickness, enhanced vascular development, and increased mesophyll size. DOP also increased stomatal density and stomatal index on both leaf surfaces, with intrinsic benefits on gas exchange and carbon assimilation. Simultaneously, DOP preserved photosynthetic pigments and significantly increased net photosynthetic rate and carboxylation instantaneous efficiency. Nutrient contents were increased in leaves, stems, and roots, while antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase) were strongly stimulated, resulting in reduced ROS accumulation, lipid peroxidation, and electrolyte leakage. These integrated responses culminated in increased biomass accumulation under root hypoxia. The results demonstrate that DOP mitigated waterlogging‐induced damage through anatomical adjustments, nutrient maintenance, redox regulation, and preservation of photosynthetic capacity, thereby inducing waterlogging tolerance in soybean plants.
Vieira et al. (2026) studied this question.