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Title: ALTERATION OF ANTIOXIDANT ENZYME GENE EXPRESSION DURING COLD ACCLIMATION OF NEAR ISOGENIC WHEAT LINES

Author
item BAEK, KWANG-HYUN - WASHINGTON STATE UNIV
item Skinner, Daniel

Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2003
Publication Date: 8/12/2003
Citation: Baek, K., Skinner, D.Z. 2003. Alteration of antioxidant enzyme gene expression during cold acclimation of near isogenic wheat lines. Plant Science. 165:1221-1227.

Interpretive Summary: Plants undergoing stress are subject to injury from oxidants, forms of oxygen that can be damaging to plant cells. In response, plants produce a variety of enzymes that deactivate the oxidants. This study was undertaken to measure how quickly the genes responsible for the production of these 'antioxidant enzymes' react to cold temperature stress in winter wheat and in spring wheat. Nine genes were studied and examples of genes that rapidly increased expression, genes that decreased expression, and genes that did not respond to cold were found. The winter wheat generally expressed these genes to higher levels than the spring wheat. These results suggested that antioxidant activity plays a significant role in the adaptation of wheat to cold temperature.

Technical Abstract: 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 dismutase (FeSOD), catalase (CAT), thylakoid-bound ascorbate peroxidase (t-APX), cytosolic gutathione reductase (GR), glutathione peroxidase (GPX), cytosolic mono-dehydroascorbate reductase (MDAR), chloroplastic dehydroascorbate reductase (DHAR). The expression levels were up-regulated (MnSOD, MDAR, t-APX, DHAR, GPX, and GR), down-regulated (CAT), or relatively constant (FeSOD and Cu,ZnSOD). The Vrn1-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.