Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
Plant Physiol Biochem. 2021 Feb;159:322-334. doi: 10.1016/j.plaphy.2020.12.033. Epub 2021 Jan 4.
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.
过多的水分以水涝或完全淹没的形式存在会导致严重的缺氧或缺氧条件，从而影响几种生理和生化过程。由于 ROS 的积累和叶片组织的损伤，导致光合作用速率下降，这是过量水分的主要后果。这些影响会降低作物的产量和质量，尤其是在敏感物种如大豆（Glycine max.）中。在缺氧条件下，植物会表达类细胞色素 P450 蛋白（Pgbs），并通过清除一氧化氮的能力参与多种与应激相关的反应。本研究通过过表达或抑制 Pgb1 基因 GmPgb1 生成了大豆植株，并评估了它们应对水涝和完全淹没条件的能力。与野生型植物相比，过表达 GmPgb1 的植株在水涝期间保持更高的光合速率和存活率。同样的植株由于呼吸爆发氧化酶同源物（RBOH）的表达减少，NADPH 氧化酶的组成部分，以及抗氧化系统的增强，表现出较低的 ROS 水平，该系统的特征是过氧化氢酶（CAT）和超氧化物歧化酶（SOD）的表达增加，以及抗坏血酸过氧化物酶（APX）的表达和活性升高。过表达 GmPgb1 的植株还表现出与过度水分恢复相关的水通道蛋白表达模式。这与下调 GmPgb1 的植株形成鲜明对比，后者的特征是光合作用速率最低、ROS 信号最强，以及许多抗氧化酶的表达和活性降低。这些研究结果表明，GmPgb1 在过量水分条件下发挥保护作用，其机制类似于水涝和淹没条件下的作用机制。
