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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

The content of lipid peroxidation product (MDA) in tall fescue 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 2: The content of lipid peroxidation product (MDA) in tall fescue 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: Water stress induced by PEG caused significant reduction (by 59%) in root elongation rate, from 17.8 mm d−1 of the non-stress control plants to 10.6 mm d−1 of the water-stressed plants (Figure 1). The exogenous treatment of roots with ASA in the nutrition solution ameliorated the inhibitory effects of water stress on root elongation, causing a 72% increase in root elongation rate compared to ASA-untreated plants exposed to water stress (Figure 1). The exogenous treatment of roots with ASA under control condition did not have significant effect on root elongation rate. Further analysis of MDA content, ROS production, antioxidant enzyme activities, and gene expression were performed only in roots treated with or without ASA under water stress, but not conducted for roots treated with ASA under the non-stress control conditions due to the lack of ASA effects on root elongation under the non-stress conditions. The MDA content of both root elongation and maturation zones in PEG-treated plants was significantly (1.81-fold in elongation zone and 1.29-fold in maturation zone) higher than that that in the non-stress control, indicating the induction of oxidative damages in the entire roots by PEG-induced water stress (Figure 2). Exogenous ASA treatment resulted in significantly lower (1.64-fold) MDA content in the elongation zone of roots exposed to water stress, compared to the water stress treatment alone, but had no significant effects on MDA content of the maturation zone.


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)

The content of lipid peroxidation product (MDA) in tall fescue 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

License
Show All Figures
getmorefigures.php?uid=PMC4591509&req=5

Figure 2: The content of lipid peroxidation product (MDA) in tall fescue 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: Water stress induced by PEG caused significant reduction (by 59%) in root elongation rate, from 17.8 mm d−1 of the non-stress control plants to 10.6 mm d−1 of the water-stressed plants (Figure 1). The exogenous treatment of roots with ASA in the nutrition solution ameliorated the inhibitory effects of water stress on root elongation, causing a 72% increase in root elongation rate compared to ASA-untreated plants exposed to water stress (Figure 1). The exogenous treatment of roots with ASA under control condition did not have significant effect on root elongation rate. Further analysis of MDA content, ROS production, antioxidant enzyme activities, and gene expression were performed only in roots treated with or without ASA under water stress, but not conducted for roots treated with ASA under the non-stress control conditions due to the lack of ASA effects on root elongation under the non-stress conditions. The MDA content of both root elongation and maturation zones in PEG-treated plants was significantly (1.81-fold in elongation zone and 1.29-fold in maturation zone) higher than that that in the non-stress control, indicating the induction of oxidative damages in the entire roots by PEG-induced water stress (Figure 2). Exogenous ASA treatment resulted in significantly lower (1.64-fold) MDA content in the elongation zone of roots exposed to water stress, compared to the water stress treatment alone, but had no significant effects on MDA content of the maturation zone.

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