Effect of Copper on Antioxidant Enzyme Activities and Mineral Nutrition of White Lupin Plants Grown in Nutrient Solution

ABSTRACT

We analyzed the effect of different copper (Cu) concentrations (0.10, 0.15, 0.20 and 0.35 mM) and time (1 day to 9 days) on several growth and biochemical parameters of roots and shoots of white lupin plants (Lupinus albus cv Estoril) grown in nutrient solution. A significant decrease in leaf fresh weight and leaf area was detected. Copper accumulated in the roots, and an impairment of nutrient translocation was only observed after six days at the highest Cu concentrations applied. A transient increase in the activity of polyphenoloxidase (EC 1.10.3.1) enforces a role for lignification as a defense strategy under enhanced Cu levels. The activities of several antioxidative enzymes were enhanced after Cu application. Our results indicate that Lupinus albus cv ‘Estoril’ is a rather resistant plant that can cope with moderate concentrations of copper, mostly by controlling up to a certain point, the uptake of excessive amounts of this metal.

Keywords:

• white lupin
• copper
• oxidative stress

ACKNOWLEDGMENTS

This work has been financially supported by Fundação para a Ciência e Tecnologia (project POCTI/AGG/33485/2002). We would like to thank Inês Gomes for the help in some of the experimental work and Marta Carneiro for assistance in leaf area determination.