Protoplasma

, Volume 245, Issue 1–4, pp 153–163

Antioxidant response of wheat roots to drought acclimation

Original Article

Abstract

Wheat (Triticum aestivum L.) seedlings of a drought-resistant cv. C306 were subjected to severe water deficit directly or through stress cycles of increasing intensity with intermittent recovery periods. The antioxidant defense in terms of redox metabolites and enzymes in root cells and mitochondria was examined in relation to membrane damage. Acclimated seedlings exhibited higher relative water content and were able to limit the accumulation of H2O2 and membrane damage during subsequent severe water stress conditions. This was due to systematic up-regulation of superoxide dismutase, ascorbate peroxidase (APX), catalase, peroxidases, and ascorbate–glutathione cycle components at both the whole cell level as well as in mitochondria. In contrast, direct exposure of severe water stress to non-acclimated seedlings caused greater water loss, excessive accumulation of H2O2 followed by elevated lipid peroxidation due to the poor antioxidant enzyme response particularly of APX, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and ascorbate–glutathione redox balance. Mitochondrial antioxidant defense was found to be better than the cellular defense in non-acclimated roots. Termination of stress followed by rewatering leads to a rapid enhancement in all the antioxidant defense components in non-acclimated roots, which suggested that the excess levels of H2O2 during severe water stress conditions might have inhibited or down-regulated the antioxidant enzymes. Hence, drought acclimation conferred enhanced tolerance toward oxidative stress in the root tissue of wheat seedlings due to both reactive oxygen species restriction and well-coordinated induction of antioxidant defense.

Keywords

Acclimation Antioxidant defense Lipid peroxidation Roots Reactive oxygen species (ROS) Water stress 

Abbreviations

ANOVA

Analysis of variance

APX

Ascorbate peroxidase

AsA

Reduced ascorbate

BSA

Bovine serum albumin

β-ME

2-Mercaptoethanol

CAT

Catalase

DHA

Oxidized ascorbate

DHAR

Dehydroascorbate reductase

EDTA

Ethylenediaminetetraacetic acid

GR

Glutathione reductase

GSH

Reduced glutathione

GSSG

Oxidized glutathione

H2O2

Hydrogen peroxide

MDHAR

Monodehydroascorbate reductase

MOPS

(3-(In-Morpholino) propanesulphonic acid

NAD(P)H-β

Nicotinamide adenine dinucleotide phosphate (reduced form)

POX

Peroxidase

ROS

Reactive oxygen species

PVP

Polyvinylpolypyrrolidone

SOD

Superoxide dismutase

TBARS

Thiobarbutaric acid-reactive substance

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Stress Physiology Laboratory, Water Technology CentreIndian Agricultural Research InstituteNew DelhiIndia

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