Lead stress-induced changes of antioxidant

Effect of Pb on MDA content

During present study, a significant increase in malondialdehyde content from

25% to 137% was observed. Here it was observed excess of Pb promoted lipid

peroxidationwithexcessiveproductionofmalondialdehydecontentincontaminated

over controls. The higher activity was observed in Calotropis procera (137%) and

Eichornia fasculata (0.83%) followed by Anisomilius molabarica (42%), Bromus

tectorum (33%), Parthenium histocarpus (26%) and Ipomea purpurea (25%)

(Fig. 3). An enhanced level of lipid peroxidation observed may be due to the

generation of toxic oxygen free radicals under metal stress. The ROS attack on free

radicalsandthepolyunsaturatedfattyacidcomponentsofmembranelipidsinitiated

lipid peroxidation, an autocatalytic process that changes membrane structure and

function. Our findings were similar to Qureshi et al., (2005) in Artemisia annua

and Withania somnifera (Khatun et al., 2008) under copper toxicity.

fig. 1 and 2: Effects of Pb concentration on chlorophyll a ,chlorophyll b content

Effect of Pb on Catalase activity

The Catalase increased from 63% to 19% compared to controls in all plants.

Highest enhancement was observed in Calotropis procera (63%) and lowest in

Bromus tectorum (19%) followed by Anisomilius molabarica (0.47%), Ipomea

purpurea (0.37%), Eichornia fasculata (0.35%) and Parthenium histocarpus

(0.25%) (Fig. 4). Elevated Catalase would lower H ₂ O ₂ levels, which reduces the

lipid peroxidation degree and lessen membrane damage by converting H ₂ O ₂ into

water and oxygen. Our results of increasing concentration of catalase activity with

the increasing concentration of Pb corroborate with the findings of Verma and

Dubey (2003) in rice plants and Pinus radiate plants (Jarvis and Leung, 2002).

Int. J. Bioinformatics and Biological Sci.: v.2 n.1&2, p. 13-22. March & June 2014

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