Effect of aluminium on peroxidase activity in roots of Al-sensitive and Al-resistant barley cultivars

Abstract

The effect of Al stress on peroxidase activity and peroxidase isozymes was studied in roots of two barley cultivars with contrasting sensitivity to Al. Al treatment induced a tremendous enhancement of guaiacol peroxidase activity especially in roots of Al-sensitive barley cv. Alfor. After 48 h of Al treatment activity of peroxidase in roots of cv. Alfor was up to 5.5 times higher than the control roots. In contrast, activity of peroxidase in the roots of Al-resistant cv. Bavaria was about one half than that in roots of Al-sensitive Alfor. SDS-PAGE analysis revealed that at least five peroxidase isozymes are activated by Al treatment. Using IEF we determined that three of Al-induced peroxidase isozymes are cationic with pI about 8.2, 8.4 and 8.6, while two other are anionic isoperoxidases with pI about 4.0 and 4.5. Al induced increase in the activity of root peroxidases correlated with the extent of Al induced root growth inhibition. The inhibition of root growth in Al-sensitive Alfor represented 44% but in Al-resistant Bavaria only 21% in comparison with control plants. Higher peroxidase activity, as well, as higher inhibition of root growth in Al-sensitive Alfor suggest that enhanced oxidative stress generated by Al treatment is significantly more stressful in Alfor than in the Al-resistant Bavaria.

Plant peroxidases: biomarkers of metallic stress

“…Several papers have discussed the relationship between the magnitude of peroxidase activity under metallic stress conditions and the degree of plant tolerance to this stress. In this context, numerous studies have shown that there are intraspecific differences on the peroxidase responses of some cultivars contaminated by a toxic amount of any metal (Tamás et al 2002;Haji Hosseini et al 2007). In fact, it was found that the most sensitive species have the higher induction rate of peroxidase activity than tolerant species which generally show a discreet increase on their peroxidase activity.…”

“…Thus, the work of Smeets et al (2005) showed the stimulation of several isoforms and the induction of others in bean leaves. In the case of aluminum, Tamás et al (2002) have shown that a toxic amount of this metal caused the stimulation of two anionic isoperoxidases in Hordeum vulgare. The qualitative and quantitative variations of isoperoxidases are generally due to a direct action of metals on the expression of genes encoding peroxidases.…”

Protein and Peroxidase Modulations in Sunflower Seedlings (Helianthus annuus L.) Treated with a Toxic Amount of Aluminium

“…This stimulation is noted on soluble fraction. Such an increase in guaiacol peroxidase activity in response to aluminium treatment was already reported in barley roots [14]. In fact, these peroxidases may play several roles in stress response to aluminium treatment [14,26] like antioxidant defence and cell wall reinforcement.…”

“…Such an increase in guaiacol peroxidase activity in response to aluminium treatment was already reported in barley roots [14]. In fact, these peroxidases may play several roles in stress response to aluminium treatment [14,26] like antioxidant defence and cell wall reinforcement. Richards et al [28] have suggested that aluminium induces expression of genes encoding peroxidase within 1 h of exposure of Arabidopsis thaliana roots to aluminium stress and this expression increases over 48 h of aluminium treatment (Figs.…”

“…In fact, it has been reported that peroxidase induction is a general response of higher plant to metallic stress conditions [7]. This enhanced activity was observed in several plant species treated with toxic amounts of cadmium [8], zinc [9], nickel [10], copper [11], lead, [12] iron [13] and aluminium [14]. It also appears that toxic metals were able to change peroxidase activity both quantitatively and qualitatively [15].…”