Manganese-induced salt stress tolerance in rice seedlings: regulation of ion homeostasis, antioxidant defense and glyoxalase systems - PubMed (original) (raw)

Manganese-induced salt stress tolerance in rice seedlings: regulation of ion homeostasis, antioxidant defense and glyoxalase systems

Anisur Rahman et al. Physiol Mol Biol Plants. 2016 Jul.

Abstract

Hydroponically grown 12-day-old rice (Oryza sativa L. cv. BRRI dhan47) seedlings were exposed to 150 mM NaCl alone and combined with 0.5 mM MnSO4. Salt stress resulted in disruption of ion homeostasis by Na+ influx and K+ efflux. Higher accumulation of Na+ and water imbalance under salinity caused osmotic stress, chlorosis, and growth inhibition. Salt-induced ionic toxicity and osmotic stress consequently resulted in oxidative stress by disrupting the antioxidant defense and glyoxalase systems through overproduction of reactive oxygen species (ROS) and methylglyoxal (MG), respectively. The salt-induced damage increased with the increasing duration of stress. However, exogenous application of manganese (Mn) helped the plants to partially recover from the inhibited growth and chlorosis by improving ionic and osmotic homeostasis through decreasing Na+ influx and increasing water status, respectively. Exogenous application of Mn increased ROS detoxification by increasing the content of the phenolic compounds, flavonoids, and ascorbate (AsA), and increasing the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), superoxide dismutase (SOD), and catalase (CAT) in the salt-treated seedlings. Supplemental Mn also reinforced MG detoxification by increasing the activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) in the salt-affected seedlings. Thus, exogenous application of Mn conferred salt-stress tolerance through the coordinated action of ion homeostasis and the antioxidant defense and glyoxalase systems in the salt-affected seedlings.

Keywords: Methylglyoxal; Nutrient homeostasis; Osmotic stress; Oxidative stress; Reactive oxygen species; Trace elements.

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Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1

Fig. 1

Phenotypic appearance of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively

Fig. 2

Fig. 2

Effect on Na+ and K+ content and their ratio and Mn content in root (a, c, e, g) and leaf (b, d, f, h) of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively. Means (±SD) were calculated from three replicates for each treatment. Values with different letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test

Fig. 3

Fig. 3

Histochemical detection of O2·- (a) and H2O2 (b) in leaf of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively

Fig. 4

Fig. 4

Histochemical detection of lipid peroxidation (a) and loss of plasma membrane integrity (b) in root of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively

Fig. 5

Fig. 5

Effect on AsA content (a), DHA content (b), AsA/DHA ratio (c), GSH content (d), GSSG content (e), GSH/GSSG ratio (f) of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively. Means (±SD) were calculated from three replicates for each treatment. Values with different letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test

Fig. 6

Fig. 6

Effect on total phenol content (a) and flavonoid content (b) of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively. Means (±SD) were calculated from three replicates for each treatment. Values with different letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test

Fig. 7

Fig. 7

Effect on APX (a) MDHAR (b), DHAR (c) and GR (d) activities of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively. Means (±SD) were calculated from three replicates for each treatment. Values with different letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test

Fig. 8

Fig. 8

Effect on SOD (a), CAT (b), GPX (c) and GST (d) activities of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively. Means (±SD) were calculated from three replicates for each treatment. Values with different letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test

Fig. 9

Fig. 9

Effect on Gly I (a) and Gly II (b) activity, and MG content (c) of rice seedlings under salt stress with and without exogenous Mn. Here, Mn and Salt indicate 0.5 mM MnSO4 and 150 mM NaCl, respectively. Means (±SD) were calculated from three replicates for each treatment. Values with different letters are significantly different at P ≤ 0.05 applying the Fisher’s LSD test

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