Oxidative stress response in spinach plants induced by cadmium

ABSTRACT

In this work we studied the effect of cadmium (Cd) (25 μM), in spinach plants (Spinacea oleracea) growing in nutrient solution, for 1, 2 and 7 days. Spinach growing in the contaminated solution showed a decrease in biomass, chlorophyll content and an increase in malondialdehyde (MDA) content, showing that photosynthetic apparatus was affected and lipid peroxidation occurred. The main defence mechanisms against the induced oxidative stress were the activation of catalase, glutathione reductase and guaiacol peroxidase. Glutathione reductase activity suggests that glutathione is involved in the response against Cd toxicity. The uptake of zinc (Zn), potassium (K), iron (Fe) and copper (Cu) was affected, mainly at the higher exposition times. Spinach leaves showed no signs of toxicity and looked healthy although containing up to 35 mg kg⁻¹ dry weight (DW) of Cd. This can present a food security issue as there is no visible indication of the high amounts of Cd in the edible parts of the plant.

KEYWORDS:

• Antioxidative enzymes
• cadmium
• lipid peroxidation
• oxidative stress
• spinach

Funding

Author Filipa R. Pinto acknowledges funding from the FCT (Lisboa, Portugal) in the form of grant SFRH/BD/81080/2011. This work was funded by FCT Research Project PTDC/AGR-AAM/102821/2008 and by the FCT-funded research unit UIQA - Research Unit Environmental Chemistry (PEst-OE/AGR/UI0528/2011).