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Effect of potassium deficiency on antioxidant status and cadmium toxicity in rice seedlings

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ABSTRACT

Background: Cadmium (Cd) is one of the most toxic heavy metals and inhibits physiological processes of plants. Potassium (K) is an essential macronutrient in plants. K deficiency and Cd stress represent two different abiotic stress conditions that occur in the field simultaneously. In this study, effects of K deficiency on antioxidant status and Cd toxicity in rice seedlings were investigated.

Results: K deficiency significantly decreased K concentration in shoots and roots. However, fresh weight and dry weight of rice seedlings were not affected by K deficiency. The activities of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase) in K-deficient leaves were higher than respective control leaves. However, K deficiency had no effect on the content of antioxidants (ascorbate and glutathione). Cd toxicity was judged by the decrease in biomass production, chlorosis, and induction of oxidative stress. Based on these criteria, we demonstrated that K deficiency protected rice seedling from Cd stress. Moreover, chlorophyll concentration was higher in K-deficient shoots and roots than their respective control shoots and roots.

Conclusions: Our results indicated that K deficiency protects rice seedlings from Cd toxicity. This protective effect of K deficiency is mainly due to enhanced antioxidant enzyme activities but not inhibition of Cd uptake.

Electronic supplementary material: The online version of this article (doi:10.1186/1999-3110-54-2) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

Effect of CdCl2on the contents of AsA (A) and GSH (C) and the ratios of AsA/DHA (B) and GSH/GSSG (D) in the second leaves of rice seedlings grown under K-sufficient (control) and -deficient (−K) conditions. Rice seedlings were grown under control and − K conditions for 12 days. Control and − K seedlings were then transferred to the control and − K nutrient solution with or without 5 μM CdCl2 for 6 days, respectively. The second leaves were then used to determine the contents of AsA, DHA, GSH, and GSSG. Bars indicates standard errors (n = 4). Values with the same letter are not significantly different at P < 0.05.
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Fig6: Effect of CdCl2on the contents of AsA (A) and GSH (C) and the ratios of AsA/DHA (B) and GSH/GSSG (D) in the second leaves of rice seedlings grown under K-sufficient (control) and -deficient (−K) conditions. Rice seedlings were grown under control and − K conditions for 12 days. Control and − K seedlings were then transferred to the control and − K nutrient solution with or without 5 μM CdCl2 for 6 days, respectively. The second leaves were then used to determine the contents of AsA, DHA, GSH, and GSSG. Bars indicates standard errors (n = 4). Values with the same letter are not significantly different at P < 0.05.

Mentions: The striking increase in lipid peroxidation and H2O2 seen in K-sufficient leaves treated with CdCl2 (Figure 4B, C), may reflect changes in the specific activities of antioxidant enzymes and contents of antioxidants. Here, we showed that the increase in the activities of SOD, APX, GR, and CAT caused by Cd was more pronounced in K-sufficient leaves than in K-deficient leaves (Figure 5A-D). AsA and GSH are important antioxidants in plants (Gill and Tuteja, 2010; Cuypers et al., 2010). It was observed that the decrease in ASA and GSH contents caused by CdCl2 was greater in K-sufficient leaves than in K-deficient leaves. The results of this study also demonstrated that Cd treatment resulted in a significant decrease in the AsA/DHA and GSH/GSSG ratios in K-sufficient leaves (Figure 6B, D). However, the AsA/DHA and GSH/GSSG ratios in − K leaves were not affected by CdCl2 (Figure 6B, D).Figure 5


Effect of potassium deficiency on antioxidant status and cadmium toxicity in rice seedlings
Effect of CdCl2on the contents of AsA (A) and GSH (C) and the ratios of AsA/DHA (B) and GSH/GSSG (D) in the second leaves of rice seedlings grown under K-sufficient (control) and -deficient (−K) conditions. Rice seedlings were grown under control and − K conditions for 12 days. Control and − K seedlings were then transferred to the control and − K nutrient solution with or without 5 μM CdCl2 for 6 days, respectively. The second leaves were then used to determine the contents of AsA, DHA, GSH, and GSSG. Bars indicates standard errors (n = 4). Values with the same letter are not significantly different at P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC5383923&req=5

Fig6: Effect of CdCl2on the contents of AsA (A) and GSH (C) and the ratios of AsA/DHA (B) and GSH/GSSG (D) in the second leaves of rice seedlings grown under K-sufficient (control) and -deficient (−K) conditions. Rice seedlings were grown under control and − K conditions for 12 days. Control and − K seedlings were then transferred to the control and − K nutrient solution with or without 5 μM CdCl2 for 6 days, respectively. The second leaves were then used to determine the contents of AsA, DHA, GSH, and GSSG. Bars indicates standard errors (n = 4). Values with the same letter are not significantly different at P < 0.05.
Mentions: The striking increase in lipid peroxidation and H2O2 seen in K-sufficient leaves treated with CdCl2 (Figure 4B, C), may reflect changes in the specific activities of antioxidant enzymes and contents of antioxidants. Here, we showed that the increase in the activities of SOD, APX, GR, and CAT caused by Cd was more pronounced in K-sufficient leaves than in K-deficient leaves (Figure 5A-D). AsA and GSH are important antioxidants in plants (Gill and Tuteja, 2010; Cuypers et al., 2010). It was observed that the decrease in ASA and GSH contents caused by CdCl2 was greater in K-sufficient leaves than in K-deficient leaves. The results of this study also demonstrated that Cd treatment resulted in a significant decrease in the AsA/DHA and GSH/GSSG ratios in K-sufficient leaves (Figure 6B, D). However, the AsA/DHA and GSH/GSSG ratios in − K leaves were not affected by CdCl2 (Figure 6B, D).Figure 5

View Article: PubMed Central

ABSTRACT

Background: Cadmium (Cd) is one of the most toxic heavy metals and inhibits physiological processes of plants. Potassium (K) is an essential macronutrient in plants. K deficiency and Cd stress represent two different abiotic stress conditions that occur in the field simultaneously. In this study, effects of K deficiency on antioxidant status and Cd toxicity in rice seedlings were investigated.

Results: K deficiency significantly decreased K concentration in shoots and roots. However, fresh weight and dry weight of rice seedlings were not affected by K deficiency. The activities of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, glutathione reductase, and catalase) in K-deficient leaves were higher than respective control leaves. However, K deficiency had no effect on the content of antioxidants (ascorbate and glutathione). Cd toxicity was judged by the decrease in biomass production, chlorosis, and induction of oxidative stress. Based on these criteria, we demonstrated that K deficiency protected rice seedling from Cd stress. Moreover, chlorophyll concentration was higher in K-deficient shoots and roots than their respective control shoots and roots.

Conclusions: Our results indicated that K deficiency protects rice seedlings from Cd toxicity. This protective effect of K deficiency is mainly due to enhanced antioxidant enzyme activities but not inhibition of Cd uptake.

Electronic supplementary material: The online version of this article (doi:10.1186/1999-3110-54-2) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus