Nickel-induced changes in carbon metabolism in wheat shoots

• Published in: Journal of plant physiology 2013-03, Vol.170 (4), p.369-377
• Main Authors: Gajewska, Ewa, Niewiadomska, Ewa, Tokarz, Krzysztof, Słaba, Mirosława, Skłodowska, Maria
• Format: Article
• Language: English
• Subjects: adverse effects; amino acids; Carbon; Carbon - metabolism; Carbon metabolism enzymes; citric acid; defense mechanisms; Enzyme Activation - drug effects; Enzymes; glucose; glucose-6-phosphate 1-dehydrogenase; isocitrate dehydrogenase; Malate; malate dehydrogenase; Metabolism; Nickel; Nickel - toxicity; oxidative stress; phosphoenolpyruvate carboxylase; Phosphoenolpyruvate Carboxylase - metabolism; phosphogluconate dehydrogenase; Photosynthesis; Photosynthesis - drug effects; Physiology; Plant Shoots - growth & development; Plant Stomata - drug effects; ribulose-bisphosphate carboxylase; Ribulose-Bisphosphate Carboxylase - metabolism; seedlings; shoots; stomatal conductance; Stress concentration; Stresses; sucrose; toxicity; Triticum - drug effects; Triticum - metabolism; Triticum aestivum; Wheat
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2012.10.012

In this study, we analyzed the toxic effect of Ni during the development of wheat shoots. Typical developmental alterations in carbon metabolism-related parameters reflecting changes associated with the transition of the seedlings from heterotrophic to autotrophic metabolism were observed in the control shoots between the 1st and the 4th days. Adverse effects of 50 and 100μM Ni became evident starting from the 4th day of growth on the metal-containing media. We found that Ni-induced stimulation of phosphoenolpyruvate carboxylase (PEPC) activity coincided with decrease in the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) level and with declines in net photosynthetic rate (PN) and stomatal conductance (gs). Application of Ni resulted in increased activities of several dehydrogenases: glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), isocitrate dehydrogenase (NADP-ICDH) and malate dehydrogenase (NADH-MDH). In contrast, the activities of malic enzymes (NADP-ME and NAD-ME) decreased due to Ni stress. Treatment with Ni led to accumulation of glucose and declined concentration of sucrose as well as considerable increases in concentrations of malic and citric acids. Our results indicate that Ni stress redirects the carbon metabolism of developing wheat shoots to provide carbon skeletons for synthesis of amino acids and organic acids as well as to supply reducing power to sustain normal metabolic processes and to support defense mechanisms against oxidative stress.