The antioxidant system in Suaeda salsa under salt stress

Abstract

L. is a typical euhalophyte and is widely distributed throughout the world. Suaeda plants are important halophyte resources, and the physiological and biochemical characteristics of their various organsand their response to salt stress have been intensively studied. Leaf succulence, intracellular ion localization, increased osmotic regulation and enhanced antioxidant capacities are important responses for Suaeda plants to adapt to salt stress. Among these responses, scavenging of reactive oxygen species (ROS) is an important mechanism for plants to withstand oxidative stress and improve salt tolerance. The generation and scavenging pathways of ROS, as well as the expression of scavenging enzymes change under salt stress. This article reviews the antioxidant system constitute of S. salsa, and the mechanisms by which S. salsaantioxidant capacity is improved for salt tolerance. In addition, the differences between types of antioxidant mechanisms in S. salsaare reviewed, thereby revealing the adaptation mechanisms of Suaeda to different habitats. The review provides important clues for the comprehensive understanding of the salt tolerance mechanisms of halophytes.

Keywords: Suaeda salsa; antioxidant system; halophyte; oxidative stress; salt-tolerance mechanism.

Figure 1.

The antioxidant system of Suaeda salsa. ①The superoxide dismutase (SOD) catalyzes the dismutation reaction of two superoxide radicals to form O₂ and H₂O₂, which is then converted to H₂O catalyzed by antioxidant enzymes. ②The catalase (CAT) is an enzymatic scavenging agent based on iron porphyrin as the prosthetic group, which can promote the rapid decomposition of H₂O₂ into H₂O and O₂. ③The glutathione peroxidase (GPX) catalyzes the binding of GSH to H₂O₂, generating H₂O and GSSH. ④Theperoxidase reductase (PrxR) scavenges H₂O₂, using thioredoxin (TRx) as a redox carrier to provide electrons. ⑤The glutathione reductase (GR) reduces GSSH to GSH through the AsA-GSH cycle, providing electron donors for the next round of H₂O₂ scavenging.