Comparison of ROS formation and antioxidant enzymes in Cleome gynandra (C 4) and Cleome spinosa (C 3) under drought stress

PubMed ID: 22118616Differences between antioxidant responses to drought in C 3 and C 4 plants are rather scanty. Even, we are not aware of any research on comparative ROS formation and antioxidant enzymes in C 3 and C 4 species differing in carboxylation pathway of same genus which would be useful to prevent other differences in plant metabolism. With this aim, relative shoot growth rate, relative water content and osmotic potential, hydrogen peroxide (H 2O 2) content and NADPH oxidase (NOX) activity, antioxidant defence system (superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR) enzymes and their isoenzymes), CAT1 mRNA level, and lipid peroxidation in seedlings of Cleome spinosa (C 3) and Cleome gynandra (C 4) species of Cleome genus exposed to drought stress for 5 and 10 day (d) were comparatively investigated. Constitutive levels of antioxidant enzymes (except SOD) were consistently higher in C. spinosa than in C. gynandra under control conditions. CAT1 gene expression in C. spinosa was correlated with CAT activity but CAT1 gene expression in C. gynandra at 10 d did not show this correlation. Drought stress caused an increase in POX, CAT, APX and GR in both species. However, SOD activity was slightly decreased in C. gynandra while it was remained unchanged or increased on 5 and 10 d of stress in C. spinosa, respectively. Parallel to results of malon dialdehyde (MDA), H 2O 2 content was also remarkably increased in C. spinosa as compared to C. gynandra under drought stress. These results suggest that in C. spinosa, antioxidant defence system was insufficient to suppress the increasing ROS production under stress condition. On the other hand, in C. gynandra, although its induction was lower as compared to C. spinosa, antioxidant system was able to cope with ROS formation under drought stress. © 2011 Elsevier Ireland Ltd.This research was supported by grant in-aid 2009-Fen-074 from Ege University Research Foundation . The authors wish to thank Dr. Julian Hibberd from University of Cambridge, U.K. for providing C. gynandra seeds and also to Assist. Prof. Dr. Ferit Kocacinar from Sutcu Imam University, Turkey for providing C. spinosa seeds. For providing Klasmann Potgrond P, we would like to thank DRT, Antalya, Turkey. We also thank Dr. Ritchie Eanes (Department of Chemistry, IYTE) for extensive proof reading of the manuscript. -

Characterization of a cDNA from Beta maritima that confers nickel tolerance in yeast

Nickel is an essential micronutrient due to its involvement in many enzymatic reactions as a cofactor. However, excess of this element is toxic to biological systems. Here, we constructed a cDNA library from Beta maritima and screened it in the yeast system to identify genes that confer resistance to toxic levels of nickel. A cDNA clone (NIC6), which encodes for a putative membrane protein with unknown function, was found to help yeast cells to tolerate toxic levels of nickel. A GFP fused form of Nic6 protein was localized to multivesicular structures in tobacco epidermal cells. Thus, our results suggest a possible role of Nic6 in nickel and intracellular ion homeostasis