effect of glutathione on antioxidant capacity of corn seedling roots under salt stress

An 80 mmol/L NaCl solution was used to simulate salt stress.

The effects of glutathione on the antioxidant enzyme activities, antioxidant substances and membrane lipid peroxidation indicators in the roots of Salvia davurica 14 seedlings under salt stress were studied.

The results show that salt stress caused oxidative stress to the root systems of corn seedlings.

The root system can resist the oxidative stress caused by salt stress by increasing the activities of antioxidant enzymes SOD, CAT and POD, as well as the molar concentration of antioxidant substance AsA.

Compared with the single salt stress, glutathione treatment can significantly increase the activities of APX and DHAR in the roots under salt stress, as well as the quality molar concentration of AsA, by 200%, 503% and 66% respectively;

it also significantly reduces the membrane permeability and the quality molar concentration of MDA, by 34% and 41% respectively.

Exogenous glutathione treatment can enhance the antioxidant capacity of the root systems of corn seedlings, thereby protecting them from damage caused by salt stress.

Salt stress often leads to an increase in the production of reactive oxygen species, thereby causing oxidative stress in plants.

Plants can enhance their stress resistance by strengthening their antioxidant systems and eliminating excessive reactive oxygen species in their bodies.

However, when the production of reactive oxygen species far exceeds the plant's ability to eliminate them, it will lead to plant aging and death.

Studying the influence of exogenous substances on the antioxidant properties of plants is of great significance for enhancing their salt tolerance.

Glutathione (GSH) is a widely present important reducing substance in plants, playing a significant role in defending against the lipid peroxidation caused by free radicals.

Studies have shown that exogenous glutathione (GSH) can enhance the salt tolerance of crops such as rice and barley.

However, at present, there are few reports on the regulation of exogenous glutathione on the antioxidant properties of corn under salt stress.

Previous studies on the regulation of plant salt tolerance by exogenous glutathione mainly focused on the leaf level. Research conducted at the root level has rarely been reported.

Since the root system is the initial part where plants respond to salt stress, studying the regulatory effect of exogenous glutathione on the antioxidant properties of corn roots from an antioxidant perspective is of great significance for enhancing its salt tolerance.

Using the 14-year-old seedlings of Sliding Jade as the material, this study investigated the effects of exogenous glutathione on the activities of antioxidant enzymes SOD, POD, CAT, APX, GR, and DHAR in the roots of corn seedlings under salt stress, as well as the physiological indicators such as the content of antioxidant substances AsA, glutathione mass molar concentration, cell membrane permeability, and malondialdehyde mass molar concentration.

The aim was to reveal the influence of exogenous glutathione on the antioxidant characteristics of the roots of corn seedlings under salt stress, and to provide a theoretical basis for the application of glutathione in corn production and cultivation management.

Materials and Methods

The experiment was conducted in the Plant Physiology and Biochemistry Laboratory of the School of Life Sciences at Henan University of Science and Technology in September 2013.

The experimental material was Slaty Jade 14. 100 corn seeds of uniform size, plump shape and free from pests and diseases were selected.

The corn seeds were washed with distilled water and then dried. 0.1% HgCl2 was used.

Soak for 20 minutes for routine disinfection.

After soaking in distilled water for 24 hours, transfer to a petri dish.

Add an appropriate amount of distilled water and cultivate in an artificial climate chamber for germination and seedling growth.

The cultivation temperature is 25°C, the light intensity is 300 μmol/(m2·s), the relative humidity is 70%, and the light duration is 10 hours per day.

When the seedlings have grown to have two leaves and one heart, select those with basically the same growth conditions, sizes and qualities for the experiment.

The experiment was divided into three treatments: control, salt stress, and GSH + salt stress.

The control group was treated by placing the root system in 100 mL of distilled water.

The salt stress treatment involves placing the root system in a 100 mL solution of 80 mmol/L NaCl for the treatment.

The GSH + salt stress treatment involves first pre-treating the roots with 50 mg/L GSH for 1 day, and then transferring them to 100 mL of 80 mmol/L NaCl solution for treatment.

One seedling was used for each treatment, with 6 repetitions.

After processing the 2D samples, various physiological indicators of the root systems of corn seedlings were measured under each treatment.

The activity of SOD was determined using the nitroblue tetrazolium (NBT) photoreduction method, with 50% inhibition of the NBT reaction being defined as one unit of enzyme activity.

The POD activity was determined by the guaiacol method, with 0.1 unit of enzyme activity defined as the change in A470 within 1 minute.

The activities of CAT, APX and DHAR were determined by ultraviolet spectrophotometry.

The activity of CAT was defined as 1 enzyme unit when the change in A240 within 1 minute was 0.1. The activity of APX was defined as 1 enzyme unit when the change in A290 within 1 minute was 0.01.

The activity of DHAR was defined as 1 enzyme unit when the change in A265 within 1 minute was 0.01.

The GR activity was determined using the reduced coenzyme II (NADPH) method. One enzyme activity unit was defined as a 0.01% change in A340 within 1 minute.

The molar concentration of AsA was determined by photometric analysis, and the molar concentration of GSH was determined by the DTNB-glutathione reductase (GR) method.

The cytoplasmic membrane permeability was determined using the DDS-307 conductance meter.

The relative permeability of the cell membrane = the conductance of the exudate before killing / the conductance of the exudate after killing.

The molar concentration of MDA was determined by the thiobarbituric acid method.

The data were processed using the SAS software, and a significance difference analysis was conducted at the 0.05 level.

Results and Analysis

1. effect of exogenous glutathione on activities of antioxidant enzymes SOD, CAT and POD in roots of corn seedlings under salt stress

Superoxide dismutase (SOD) is one of the important protective enzymes within cells that remove reactive oxygen species.

The strength of its activity reflects the adaptability of the plant body to adverse conditions.

Catalase (CAT) can break down H2O2 into molecular oxygen and water, removing H2O2 from the body and protecting cells from the toxicity of H2O2.

It is one of the important protective enzymes in the biological defense system.

Peroxidase (POD) is one of the important protective enzymes in plant cells that remove the reactive oxygen species H2O2.

The level of POD activity is also an important indicator for evaluating the plant's resistance to adverse conditions.

The activities of SOD, CAT and POD for each treatment are shown in Table 1.

The salt stress significantly increased the SOD activity of the roots of corn seedlings, indicating that corn seedlings can enhance their resistance to salt stress by increasing the SOD activity in their roots.

Compared with the single salt stress treatment, the treatment of exogenous glutathione + salt stress significantly reduced the SOD activity of the roots, but the SOD activity of the roots in the exogenous glutathione + salt stress treatment was still significantly higher than that of the control.

Compared with the control group, salt stress significantly increased the CAT activity in the roots of corn seedlings.

This indicates that corn seedlings can enhance their ability to resist salt stress by increasing the CAT activity in their leaves.

Compared with the control and the single salt stress treatment, the exogenous glutathione + salt stress treatment significantly reduced the CAT activity in the roots.

This indicates that exogenous glutathione inhibits the activity of CAT in the roots.

Compared with the control group, salt stress significantly increased the POD activity in the roots of corn seedlings.

This indicates that the root systems of the seedlings can enhance their ability to remove H2O2 by increasing the POD activity.

Compared with the single salt stress treatment, the treatment of exogenous glutathione + salt stress had no significant effect on the POD activity of the roots.

This indicates that the exogenous application of glutathione cannot enhance the salt tolerance of corn seedlings by increasing the POD activity of their roots under salt stress.

Studies have shown that exogenous glutathione can significantly increase the activities of SOD, CAT and POD, thereby enhancing salt tolerance.

Exogenous glutathione can significantly increase the SOD activity in rice leaves.

All of these are inconsistent with the research results presented in the article.

This might be related to the different materials used and the organs being studied.

2. effect of exogenous glutathione on activity of ASA-glutathione metabolic enzymes in root systems of corn seedlings under salt stress

Ascorbate peroxidase (APX) is an enzyme that uses ascorbic acid as an electron donor to remove H2O2. It is an important component of the antioxidant system.

Under salt stress, the activity of APX in the root system of corn seedlings significantly decreased, indicating that the root system of corn seedlings, due to the reduced APX activity, has a decreased ability to resist salt stress.

Compared with the single salt stress treatment, the treatment of exogenous glutathione + salt stress significantly increased the APX activity in the roots.

This indicates that exogenous glutathione can enhance the root APX activity and thereby strengthen the root's ability to resist salt stress.

Exogenous application of glutathione can increase the APX activity in the roots of corn and enhance the plant's ability to remove H2O2, thereby alleviating the damage caused by salt stress to the plant.

Compared with the control group, the GR activity of the roots under the single salt stress treatment and the GR activity of the roots under the combined treatment of exogenous glutathione and salt stress were all significantly decreased.

Moreover, there was no significant difference between the GR activity of the roots under the single salt stress treatment and that under the combined treatment of exogenous glutathione and salt stress.

This indicates that exogenous application of glutathione has no significant effect on the GR activity of corn roots under salt stress.

Compared with the control group, the DHAR activity in the root systems of corn seedlings under salt stress was significantly reduced.

This indicates that the root systems of corn seedlings, due to the decreased DHAR activity, have a reduced ability to resist salt stress.

Compared with the single salt stress treatment, the treatment of exogenous glutathione + salt stress significantly increased the DHAR activity of the roots.

This indicates that adding glutathione can enhance the DHAR activity of the roots, thereby strengthening their ability to resist salt stress.

This indicates that exogenous glutathione can enhance the root system's DHAR activity and thereby increase its ability to resist salt stress.

Exogenous application of glutathione can increase the DHAR activity in corn roots and enhance their resistance.

Studies have shown that exogenous glutathione can significantly enhance the activity of GR under salt stress conditions.

Exogenous glutathione can significantly enhance the activities of APX and GR in rice leaves under salt stress conditions.

In this study, it was not found that exogenous glutathione could enhance the GR activity in the roots of corn under salt stress.

This might be related to the different materials used and the organs being studied.

3. effect of exogenous glutathione on quality molar concentrations of antioxidant substances ASA and glutathione in root systems of corn seedlings under salt stress

The non-enzymatic antioxidant substance ascorbic acid (AsA) in reduced form, with the participation of APX, removes hydrogen peroxide within the cells, thereby alleviating the membrane lipid peroxidation damage caused by adverse conditions.

Glutathione is a ubiquitous reducing substance in plants and plays a significant role in defending against the lipid peroxidation caused by free radicals.

The salt stress significantly increased the molar concentration of AsA in the root system of corn seedlings.

This indicates that corn seedlings can enhance their resistance to salt stress by increasing the molar concentration of AsA in their root systems.

Compared with the single salt stress treatment, the treatment of exogenous glutathione + salt stress significantly increased the molar concentration of AsA in the roots.

This indicates that exogenous glutathione can enhance the root's resistance to salt stress by increasing the molar concentration of AsA.

The salt stress caused an increase in the molar concentration of glutathione in the root system, but the difference was not significant.

This indicates that the corn seedlings cannot enhance their ability to resist salt stress by increasing the molar concentration of glutathione in the root system.

Compared with the single salt stress treatment, the treatment of exogenous glutathione + salt stress had no significant effect on the glutathione mass molar concentration of the young plant roots.

This indicates that exogenous glutathione cannot enhance the plant's resistance to salt stress by increasing the glutathione mass molar concentration in the roots.

Studies have shown that exogenous glutathione can significantly increase the molar concentration of glutathione under salt stress;

exogenous glutathione can significantly increase the molar concentrations of AsA and glutathione in rice leaves by 3.

However, in this study, it was not found that exogenous glutathione could increase the molar concentration of glutathione in the roots of corn under salt stress.

This might be related to the different materials used and the organs studied.

4. effect of exogenous glutathione on membrane permeability and MDA mass-mole concentration of maize seedling roots under salt stress

The cell membrane has selective permeability and serves as the boundary membrane for the exchange of substances and information between the inside and outside of plant cells.

Any damage to the membrane will lead to an increase in membrane permeability, thereby causing disorder in the plant's metabolism.

The salt stress significantly increases the permeability of the root cell membranes.

This indicates that the salt stress causes damage to the root cell membranes, resulting in a significant increase in their membrane permeability.

This is consistent with the previous research results.

Compared with the single salt stress treatment, the treatment with exogenous glutathione combined with salt stress significantly reduced the membrane permeability of root cells.

This indicates that exogenous glutathione can alleviate the damage caused by salt stress to the root cell membranes.

Under the treatment of exogenous glutathione and salt stress, the membrane permeability of the roots remained higher than that of the control group.

This indicates that exogenous glutathione can only alleviate the damage to the cell membrane caused by salt stress to a certain extent.

Under adverse conditions, plants often undergo membrane lipid peroxidation.

Malondialdehyde (MDA) is one of the products, and it is usually used as an indicator of lipid peroxidation to represent the degree of membrane peroxidation and the strength of plant's adaptability to adverse conditions.

The salt stress significantly increased the molar concentration of MDA in the roots of corn seedlings.

This indicates that the salt stress caused oxidative damage to the cell membranes of the root systems of the seedlings.

Compared with the single salt stress treatment, the treatment of exogenous glutathione + salt stress significantly reduced the MDA mass concentration in the roots.

This indicates that exogenous glutathione can alleviate the oxidative damage to the cell membrane caused by salt stress.

The MDA mass molar concentration in the roots treated with exogenous glutathione was still significantly higher than that of the control group.

This indicates that exogenous glutathione can only alleviate, to a certain extent, the oxidative damage to the cell membrane caused by salt stress.

Exogenous application of glutathione can enhance the antioxidant capacity of the root systems of corn seedlings under salt stress, thereby improving their salt tolerance.