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Ascorbic acid mitigation of water stress-inhibition of root growth in association with oxidative defense in tall fescue (Festuca arundinacea Schreb.).

Xu Y, Xu Q, Huang B - Front Plant Sci (2015)

Bottom Line: In addition, free ascorbate and total ascorbate content were significantly higher in roots treated with ASA under water stress than those without ASA treatment.The enzymatic activities for ROS scavenging-related genes were not significantly altered by ASA treatment under water stress, while transcript abundances of genes encoding superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monohydroascorbate reductase showed significant decreases in the root elongation zone and significant increases in the root maturation zone treated with ASA under water stress.The results suggested that exogenous treatment of roots with ASA enhanced root elongation under water stress, which could be attributed by increasing non-enzymatic antioxidant production, suppressing ROS toxicity and up-regulating gene expression of cell-wall loosening proteins controlling cell expansion.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Biology and Pathology, Rutgers University New Brunswick, NJ, USA.

ABSTRACT
Root growth inhibition by water stress may be related to oxidative damages. The objectives of this study were to determine whether exogenous application of ascorbic acid (ASA) could mitigate root growth decline due to water stress and whether ASA effects on root growth could be regulated through activating non-enzymatic or enzymatic antioxidant systems in perennial grass species. Tall fescue (Festuca arundinacea Schreb. cv. "K-31") plants were grown in nutrient solution, and polyethylene glycol (PEG)-8000 was added into the solution to induce water stress. For exogenous ASA treatment, ASA (5 mM) was added into the solution with or without PEG-8000. Plants treated with ASA under water stress showed significantly increased root growth rate, and those roots had significantly lower content of reactive oxygen species (ROS) (H2O2 and O[Formula: see text] content) than those without ASA treatment. Malondialdehyde content in root tips treated with ASA under water stress was also significantly reduced compared with those under water stress alone. In addition, free ascorbate and total ascorbate content were significantly higher in roots treated with ASA under water stress than those without ASA treatment. The enzymatic activities for ROS scavenging-related genes were not significantly altered by ASA treatment under water stress, while transcript abundances of genes encoding superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monohydroascorbate reductase showed significant decreases in the root elongation zone and significant increases in the root maturation zone treated with ASA under water stress. Transcripts of genes for expansins and xyloglucan endotransglycosylases showed increased abundances in ASA-treated root maturation zone under water stress, indicating that ASA could accelerated cell wall loosening and cell expansion. The results suggested that exogenous treatment of roots with ASA enhanced root elongation under water stress, which could be attributed by increasing non-enzymatic antioxidant production, suppressing ROS toxicity and up-regulating gene expression of cell-wall loosening proteins controlling cell expansion.

No MeSH data available.


Related in: MedlinePlus

Relative gene expression level of XET1 (A), XET2 (B), and XET3 (C) in tall fescue roots exposed to non-stress control, water stress, and water stress with ASA treatment. The data represent mean ± SE (n = 4 replicated pots of plants and each pot with multiple plants). Columns marked with the same letter are not significantly different at p < 0.05.
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Figure 12: Relative gene expression level of XET1 (A), XET2 (B), and XET3 (C) in tall fescue roots exposed to non-stress control, water stress, and water stress with ASA treatment. The data represent mean ± SE (n = 4 replicated pots of plants and each pot with multiple plants). Columns marked with the same letter are not significantly different at p < 0.05.

Mentions: The expression levels of five expansin genes (EXP-A3, EXP-A4, EXP-A5, EXP-B4, and EXP-B7) and three XET genes (XET1, XET2, and XET3) regulating cell-wall loosening that were available from the tall fescue EST database, were examined to determine whether effects of water stress and ASA treatment on root elongation involve changes in different expansin and XET genes. Among five expansin genes, only EXP-A3 exhibited differential expression in the root elongation and maturation zones among the non-stress control water stress and ASA treatment (Figure 11), while others did not show clear patterns in response to either water stress or ASA treatment in both root elongation and maturation zones (data not shown). Transcript level of EXP-A3 significantly increased in the root elongation zone, but decreased in the maturation zone under water stress alone, while ASA treatment reversed EXP-A3 responses to water stress, with a reduction and increase in the transcript level in the root elongation zone and maturation zone, respectively, compared to water stress alone (Figure 11). XET1, XET2, and XET3 transcript levels in the root elongation zone were not significantly changed with water stress or ASA treatment (Figures 12A–C). In the root maturation zone, water stress led to significant decrease for XET1 (22.0%), XET2 (26.0%), and XET3 (43.5%); exogenous ASA treatment of roots under water stress increased the transcript level of XET2 compared to with water stress alone, although it did not have significant effects on XET1 and XET3 (Figures 12A,C).


Ascorbic acid mitigation of water stress-inhibition of root growth in association with oxidative defense in tall fescue (Festuca arundinacea Schreb.).

Xu Y, Xu Q, Huang B - Front Plant Sci (2015)

Relative gene expression level of XET1 (A), XET2 (B), and XET3 (C) in tall fescue roots exposed to non-stress control, water stress, and water stress with ASA treatment. The data represent mean ± SE (n = 4 replicated pots of plants and each pot with multiple plants). Columns marked with the same letter are not significantly different at p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

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Figure 12: Relative gene expression level of XET1 (A), XET2 (B), and XET3 (C) in tall fescue roots exposed to non-stress control, water stress, and water stress with ASA treatment. The data represent mean ± SE (n = 4 replicated pots of plants and each pot with multiple plants). Columns marked with the same letter are not significantly different at p < 0.05.
Mentions: The expression levels of five expansin genes (EXP-A3, EXP-A4, EXP-A5, EXP-B4, and EXP-B7) and three XET genes (XET1, XET2, and XET3) regulating cell-wall loosening that were available from the tall fescue EST database, were examined to determine whether effects of water stress and ASA treatment on root elongation involve changes in different expansin and XET genes. Among five expansin genes, only EXP-A3 exhibited differential expression in the root elongation and maturation zones among the non-stress control water stress and ASA treatment (Figure 11), while others did not show clear patterns in response to either water stress or ASA treatment in both root elongation and maturation zones (data not shown). Transcript level of EXP-A3 significantly increased in the root elongation zone, but decreased in the maturation zone under water stress alone, while ASA treatment reversed EXP-A3 responses to water stress, with a reduction and increase in the transcript level in the root elongation zone and maturation zone, respectively, compared to water stress alone (Figure 11). XET1, XET2, and XET3 transcript levels in the root elongation zone were not significantly changed with water stress or ASA treatment (Figures 12A–C). In the root maturation zone, water stress led to significant decrease for XET1 (22.0%), XET2 (26.0%), and XET3 (43.5%); exogenous ASA treatment of roots under water stress increased the transcript level of XET2 compared to with water stress alone, although it did not have significant effects on XET1 and XET3 (Figures 12A,C).

Bottom Line: In addition, free ascorbate and total ascorbate content were significantly higher in roots treated with ASA under water stress than those without ASA treatment.The enzymatic activities for ROS scavenging-related genes were not significantly altered by ASA treatment under water stress, while transcript abundances of genes encoding superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monohydroascorbate reductase showed significant decreases in the root elongation zone and significant increases in the root maturation zone treated with ASA under water stress.The results suggested that exogenous treatment of roots with ASA enhanced root elongation under water stress, which could be attributed by increasing non-enzymatic antioxidant production, suppressing ROS toxicity and up-regulating gene expression of cell-wall loosening proteins controlling cell expansion.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Biology and Pathology, Rutgers University New Brunswick, NJ, USA.

ABSTRACT
Root growth inhibition by water stress may be related to oxidative damages. The objectives of this study were to determine whether exogenous application of ascorbic acid (ASA) could mitigate root growth decline due to water stress and whether ASA effects on root growth could be regulated through activating non-enzymatic or enzymatic antioxidant systems in perennial grass species. Tall fescue (Festuca arundinacea Schreb. cv. "K-31") plants were grown in nutrient solution, and polyethylene glycol (PEG)-8000 was added into the solution to induce water stress. For exogenous ASA treatment, ASA (5 mM) was added into the solution with or without PEG-8000. Plants treated with ASA under water stress showed significantly increased root growth rate, and those roots had significantly lower content of reactive oxygen species (ROS) (H2O2 and O[Formula: see text] content) than those without ASA treatment. Malondialdehyde content in root tips treated with ASA under water stress was also significantly reduced compared with those under water stress alone. In addition, free ascorbate and total ascorbate content were significantly higher in roots treated with ASA under water stress than those without ASA treatment. The enzymatic activities for ROS scavenging-related genes were not significantly altered by ASA treatment under water stress, while transcript abundances of genes encoding superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monohydroascorbate reductase showed significant decreases in the root elongation zone and significant increases in the root maturation zone treated with ASA under water stress. Transcripts of genes for expansins and xyloglucan endotransglycosylases showed increased abundances in ASA-treated root maturation zone under water stress, indicating that ASA could accelerated cell wall loosening and cell expansion. The results suggested that exogenous treatment of roots with ASA enhanced root elongation under water stress, which could be attributed by increasing non-enzymatic antioxidant production, suppressing ROS toxicity and up-regulating gene expression of cell-wall loosening proteins controlling cell expansion.

No MeSH data available.


Related in: MedlinePlus