What is glutathione?
Glutathione (GSH), as a multifunctional antioxidant existing in plants, is not only responsible for clearing excess reactive oxygen species (ROS) produced by cell metabolism, but also acts as an umbrella when cells are subjected to stress, reducing the degree of cell damage caused by membrane lipid peroxidation.
This paper aims to explore the different types of glutathione, its physiological mechanisms in plants, and its unique protective role against stresses such as temperature, drought, heavy metals, and salts.
We also hope to deepen the understanding of the mechanism of plant antioxidant system through the study of GSH, so as to provide theoretical basis and technical support for improving crop stress resistance.
The diversity of glutathione
Glutathione is a tripeptide structure composed of three amino acids, glutamic acid, cysteine and glycine.
Its molecules contain a group of active sulfhydryl groups (-SH), which allows it to effectively bind to ROS and other harmful substances, thus playing a detoxification effect.
The biosynthesis of GSH mainly relies on the synergistic action of two key enzymes: glutamate-cysteine ligase (GCL) and GSH synthetase (GS).
The physiological mechanism of glutathione
Glutathione has a variety of functions in plants, including but not limited to:
1. Scavenging free radicals in cells:
GSH is converted to oxidized glutathione (GSSG) by reacting with ROS, thereby restoring intracellular REDOX balance.
2. Binding toxic heavy metals:
By forming stable complexes with heavy metal ions such as lead and mercury, GSH helps plants eliminate or passivate these harmful substances.
3. Promote the absorption and transport of amino acids:
GSH also plays an important role in the metabolism of amino acids.
Glutathione in resistance to stress
Due to its unique chemical properties, GSH shows strong protective effects in plants under different types of stress:
1. Temperature stress:
When plants are exposed to extreme temperatures, glutathione can maintain a stable state inside cells by regulating the AsA-GSH cycle, reducing the damage of cold and heat shock to cells.
2. Drought stress:
Under drought conditions, mutants of GSH S-transferase (GST) showed higher drought tolerance, indicating the importance of GSH in water management.
3. Heavy metal stress:
It was found that exogenous GSH could significantly alleviate the inhibitory effect of heavy metal pollution on plant growth and promote root development.
4. Salt stress:
Excessive salt can cause severe stress to plants, but glutathione is able to fight methylglyoxal (MDA) accumulation by maintaining high levels of the reduced form and regulating glycosylation reactivity, protecting cells from damage.