Changes in the antioxidative enzyme activities and lipid peroxidation in wheat seedlings exposed to cadmium and lead stress

Abstract

Wheat seedlings were grown in presence of CdCl2 (0-200 µM) and Pb(NO3)2 (0-2000 µM) separately. The growth of metal-treated seedlings was significantly depressed. The activities of antioxidative enzymes namely superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (POX) were altered both in root and shoot tissues of 7-d-old seedlings. Under Cd stress, SOD activity in roots was undetectable even at the lowest Cd concentration (50 µM) whereas in shoots it declined sharply with increasing Cd levels. The activity of CAT declined to a greater extent in roots than in shoots. Even though the POX activity increased nine times in shoots, a decreasing trend was observed in root tissues due to Cd stress. Under Pb stress, the induction in SOD activity and decline in CAT activity were sharper in root tissues than in their shoot counterparts. The POX activity increased both in roots and shoots under Pb stress. Malondialdehyde concentration increased in both roots and shoots of Cd- and Pb-treated seedlings. The results suggest that metal toxicity was associated with oxidative stress. The decline in CAT activity may be the probable reason behind the Cd- and Pb-induced oxidative stress, since the alterations in SOD and POX activities showed different trends under these metal stresses.

Oxidative stress and antioxidant defense mechanism in mung bean seedlings after lead and cadmium treatments

“…Our results showed that the activity of APX was reduced under Pb and Cd stress, which could be due to its inhibition by these metals, as supported by Das et al (1997), who reported that Cd is a known inhibitor of enzymes. Our results also support the findings of Dey et al (2007), who reported almost complete loss of APX activity in pine roots. Low activity of the APX enzyme showed poor activity of the H 2 O 2 scavenging system, whereas increased activity of antioxidant enzymes is the reflection of metal tolerance.…”

“…Several researchers found increased protein synthesis under metal stress. Dey et al (2007) observed that under Pb and Cd stress, wheat seedlings had increased protein contents. The increase in protein under Pb stress observed in the present study is in agreement with the findings of Singh et al (2011), who reported an increase in protein in Brassica campestris roots under Pb stress.…”

The impacts of heavy metals on oxidative stress and growth of spring barley

“…The investigations of the heavy metal impact on different plant species showed that various metals, independently of their redox-activity, caused an increase in MDA level [10,18,[36][37][38]. In our study dosedependent increase in MDA content was detected in the leaves of spring barley treated with all investigated metals (Cu, Cd, Cr, Ni, Pb and Zn), however, the level of MDA increase was very different.…”

Response of Cucumis sativus L. seedlings to Pb exposure

“…This result corroborates with that presented by Mishra and Choudhari (1998) in Pbexposed rice. In fact, Pb toxicity is reported to inhibit growth of several plants (Singh et al, 1997;Mishra et al, 2006;Romeiro et al, 2006;Dey et al, 2007). However, among the different metals tested in cucumber (Cd, Cu, Pb) and in radish (Raphanus sativus) (Cd, Hg, Zn, Pb), Pb was the least toxic to growth of seedlings (Morsch et al, 2002;An et al, 2004).…”