Excess moisture in the form of waterlogging or full submergence can cause severe conditions of hypoxia or anoxia compromising several physiological and biochemical processes. A decline in photosynthetic rate due to accumulation of ROS and damage of leaf tissue are the main consequences of excess moisture. These effects compromise crop yield and quality, especially in sensitive species, such as soybean (Glycine max.). Phytoglobins (Pgbs) are expressed during hypoxia and through their ability to scavenge nitric oxide participate in several stress-related responses. Soybean plants over-expressing or suppressing the Pgb1 gene GmPgb1 were generated and their ability to cope with waterlogging and full submergence conditions was assessed. Plants over-expressing GmPgb1 exhibited a higher retention of photosynthetic rate during waterlogging and survival rate during submergence relative to wild type plants. The same plants also had lower levels of ROS due to a reduction in expression of Respiratory Burst Oxidase Homologs (RBOH), components of the NADPH oxidase enzyme, and enhanced antioxidant system characterized by higher expression of catalases (CAT) and superoxide dismutase (SOD), as well as elevated expression and activity of ascorbate peroxidase (APX). Plants over-expressing GmPgb1 also exhibited an expression pattern of aquaporins typical of excess moisture resilience. This was in contrast to plants downregulating GmPgb1 which were characterized by the lowest photosynthetic rates, higher ROS signal, and reduced expression and activities of many antioxidant enzymes. Results from these studies suggest that GmPgb1 exercises a protective role during conditions of excess moisture with similar mechanisms operating during waterlogging and submergence.

浸水或完全淹没形式的过量水分会导致严重的缺氧或缺氧状况，从而损害多种生理和生化过程。由于ROS积累和叶组织损伤导致光合速率下降是水分过多的主要后果。这些影响会损害作物产量和质量，尤其是敏感品种，例如大豆 ( Glycine max. )。植物珠蛋白 (Pgbs) 在缺氧期间表达，并通过其清除一氧化氮的能力参与多种应激相关反应。生成了过度表达或抑制Pgb1基因GmPgb1的大豆植物，并评估了它们应对涝灾和完全淹没条件的能力。相对于野生型植物，过表达GmPgb1的植物在淹水期间表现出更高的光合速率保留率和在淹没期间的存活率。由于呼吸爆发氧化酶同系物( RBOH )、NADPH 氧化酶成分的表达减少，同一植物的 ROS 水平也较低，并且抗氧化系统增强，其特征是过氧化氢酶 (CAT) 和超氧化物歧化酶 (SOD) 的表达较高，以及抗坏血酸过氧化物酶 (APX) 的表达和活性升高。过度表达GmPgb1的植物还表现出典型的过度水分恢复能力的水通道蛋白表达模式。这与下调GmPgb1的植物形成鲜明对比，后者的特征是最低的光合速率、更高的 ROS 信号以及许多抗氧化酶的表达和活性降低。 这些研究的结果表明， GmPgb1在水分过多的情况下发挥保护作用，在水涝和淹没期间发挥类似的机制。