Full Length Research Paper

Antioxidant enzymes as bio-markers for copper tolerance in safflower (Carthamus tinctorius L.)

Ali Ahmed¹, Ammarah Hasnain¹, Saeed Akhtar², Asma Hussain¹, Abaid-ullah⁴, Ghulam Yasin¹, Abdul Wahid¹ and Seema Mahmood^1,3*

¹Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan, 60800, Pakistan

²Department of Food Science and Technology, University College of Agriculture,

Bahauddin Zakariya University, Multan, Pakistan.

³Visiting Professor, Division of Environment and Evolutionary Biology, University of Glasgow, Scotland, U.K G12 8QQ.

⁴Department of Biosciences, Comsat Institute of Technology, Islamabad, Pakistan.

*Corresponding author. E-mail: drseemapk@gmail.com.  Tel: 0092-61-9210393.

Fax: 0092-61-9210098.

Abbreviations: ROS, Reactive oxygen species; MDA, malondialdehyde; SOD, superoxide dismutase; POD, peroxidise; CAT, catalase; TBA, thiobarbituric acid; NBT, nitro-blue tetrazolium.

Accepted 9 July, 2010

   Abstract

Activities of antioxidants enzymes were investigated in order to evaluate protective mechanism of plants against oxidative stress induced by high concentration of copper. Safflower (Carthamus tinctorius L.) plants were exposed to 100 µM copper (Cu) for two weeks under controlled environmental conditions using hydroponic culture. Cu induced changes in chlorophyll and carotenoids pigments. More Cu accumulated in the roots as compared with the leaves. Level of lipid peroxidation and antioxidative enzyme activities (peroxidase, catalase and superoxide dismutase) also correlated with the Cu content of the plant tissues. However, restricted transfer of the metal to the foliage and enhanced activity of peroxidase, catalase and superoxide dismutase may be of great significance for scavenging oxidative stress caused by excessive copper in safflower plants. Thus, these antioxidant enzymes served as good predictors for the evaluation of heavy metal tolerance.

Key words: Carthamus tinctorius, copper stress, oxidative damage, antioxidant defense.