Alteration of antioxidant enzyme gene expression during cold acclimation of near-isogenic wheat lines

Reactive oxygen species (ROS) are harmful to living organisms due to the potential oxidation of membranes, DNA, proteins, and carbohydrates. Freezing injury has been shown to involve the attack of ROS. Antioxidant enzymes can protect plant cells from oxidative stress imposed by freezing injury; therefore, cold acclimation may involve an increase in the expression of antioxidant enzymes. In this study, quantitative RT-PCR was used to measure the expression levels of antioxidant enzymes during cold acclimation in near-isogenic lines (NILs) of wheat, differing in the Vrn1-Fr1 chromosome region that conditions winter versus spring wheat growth habit. The antioxidant genes monitored were mitochondrial manganese superoxide dismutase (MnSOD), chloroplastic Cu,Zn superoxide dismutase (Cu,ZnSOD), iron superoxide dismulase (FeSOD), catalase (CAT), thylakoid-bound ascorbate peroxidase (t-APX), cytosolic glutathione reductase (GR), glutathione peroxidase (GPX), cytosolic mono-dehydroascorbate reductase (MDAR), chloroplastic dehydroascorbate reductase (DHAR). The expression levels were upregulated (MnSOD, MDAR, t-APX, DHAR, GPX, and GR), downregulated (CAT), or relatively constant (FeSOD and Cu,ZnSOD). The Vrn-Fr1 region seemed to have a role in regulating the expression level of some of the antioxidant enzyme genes because t-APX, CAT and MnSOD expressed to significantly higher levels in the winter wheat NIL than the spring wheat NIL after 4 weeks' cold acclimation. (C) 2003 Elsevier Ireland Ltd. All rights reserved.