Differential biochemical responses of wheat shoots and roots to nickel stress: antioxidative reactions and proline accumulation
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Wheat (Triticum aestivum L. cv. ‘Zyta’) seedlings were treated with 10, 100 and 200 μM Ni. Tissue Ni accumulation, length, relative water content (RWC), proline and H2O2 concentrations as well as the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POD) and glutathione S-transferase (GST) were studied in the shoots and roots after 6 days of Ni exposure. Treatment with Ni, except for its lowest concentration, resulted in a significant reduction in wheat growth. In comparison to the shoots, the roots showed greater inhibition of elongation, which corresponded with higher accumulation of Ni in these organs. Both shoots and roots responded to Ni application with a decrease in RWC and enhancement in proline concentration. Greater dehydration of the shoot tissue was accompanied by more intense accumulation of proline. Treatment of the wheat seedlings with the highest concentration of Ni led to about 60% increase in H2O2 concentration in both studied organs. Apart from CAT, constitutive activities of antioxidative enzymes were much higher in the roots than in the shoots. Exposure of the seedlings to Ni resulted in SOD activity decline, which was more marked in the roots. While the shoots showed a substantial decrease (up to 30%) in CAT activity, in the roots the activity of this enzyme remained unchanged. After Ni application APX, POD and GST activities increased several-fold in the shoots, whereas in the roots they were not significantly altered. The results suggest that differential antioxidative responses of the shoots and roots of wheat seedlings to Ni stress might be related to diverse constitutive levels of antioxidant enzyme activities in both organs.
KeywordsAntioxidative enzymes Glutathione S-transferase Hydrogen peroxide Nickel Proline Triticum aestivum L.
Nitro blue tetrazolium
Reactive oxygen species
Relative water content
This work was partly supported by University of Łódź Grant No 505/402. The authors are grateful to Dr. Z. Nita (Hodowla Roślin Strzelce Sp. z o.o., Poland) for supplying the wheat seeds.
- Chen L-M, Lin CC, Kao CH (2000) Copper toxicity in rice seedlings: changes in antioxidative enzyme activities, H2O2 level, and cell wall peroxidase activity in roots. Bot Bull Acad Sin 41:99–103Google Scholar
- Edwards R, Dixon DD (2004) Metabolism of natural and xenobiotic substrates by the plant glutathione S-transferase superfamily. In: Sandermann H (eds) Molecular ecotoxicology of plants. Ecological studies, vol 170, Springer-Verlag Berlin, Heidelberg, pp 17–50Google Scholar
- Gabbrielli R, Pandolfini T, Espen L, Palandri MR (1999) Growth, peroxidase activity and cytological modifications in Pisum sativum seedlings exposed to Ni2+ toxicity. J Plant Physiol 155:639–645Google Scholar
- Gaspar T, Penel C, Hagege D, Greppin H (1991) Peroxidases in plant growth, differentiation, and development processes. In: Łobarzewski J, Greppin H, Penel C, Gaspar T (eds) Biochemical, molecular and physiological aspects of plant peroxidases. University M. Curie-Skłodowska, Lublin, pp. 249–280Google Scholar
- Habig WH, Pabst MJ, Jakoby WB (1974) Glutathione S-transferases. The first enzymatic step in mercapturic acid formation. J Biol Chem 246:7130–7139Google Scholar
- Kavi Kishor PB, Sangam S, Amrutha RN, Sri Laxmi P, Naidu KR, Rao KRSS, Rao S, Reddy KJ, Theriappan P, Sreenivasulu N (2005) Regulation of proline biosynthesis, degradation, uptake and transport in higher plants: its implications in plant growth and abiotic stress tolerance. Curr Sci 88:424–438Google Scholar
- Matysik J, Alia, Bhalu B, Mohanty P (2002) Molecular mechanisms of quenching of reactive oxygen species by proline under stress in plants. Curr Sci 82:525–532Google Scholar
- Nakano Y, Asada K (1981) Hydrogen peroxide is scavenged by ascorbate-specific peroxidase in spinach chloroplasts. Plant Cell Physiol 22:867–880Google Scholar
- Pandolfini T, Gabbrielli R, Ciscato M (1996) Nickel toxicity in two durum wheat cultivars differing in drought sensitivity. J Plant Nutr 19:1611–1627Google Scholar