Journal of Hazardous Materials 178 (2010) 1128–1131 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Short communication Membrane damage and solute leakage from germinating pea seed under cadmium stress Sondès Rahoui, Abdelilah Chaoui, Ezzeddine El Ferjani ∗ Bio-Physiologie Cellulaires, Département des Sciences de la Vie, Faculté des Sciences de Bizerte, 7021 Zarzouna, Tunisia article info Article history: Received 4 August 2009 Received in revised form 30 December 2009 Accepted 25 January 2010 Available online 1 February 2010 Keywords: Cadmium Germination Lipid peroxidation Pisum sativum L. abstract Seed germination represents a limiting stage of plant life cycle under heavy metal stress situation. Delay in germination can be associated with disorders in the event chain of germinative metabolism which is a highly complex multistage process, but one of underlying metabolic activities following imbibition of seed is the storage mobilization. The influence of cadmium on carbohydrates and aminoacids export from cotyledon to embryonic axis during germination of pea seed was investigated. Compared to the control, Cd caused a restriction in reserve mobilization as evidenced by the pronounced increase in cotyledon/embryo ratios of total soluble sugars, glucose, fructose and aminoacids. Moreover, the nutrient concentrations, as well as the electrical conductivity of germination medium were determined to quantify the extent of solute leakage. Such nutrients were lost into the imbibition medium at the expense of suitable mobilization to the growing embryonic axis. This was concomitant with an over-accumulation of lipid peroxidation products in Cd-poisoned embryonic tissues. However, the impairment of membrane integrity cannot be due to a stimulation in lipoxygenase activity, since the later was markedly inhibited after Cd exposure. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Cadmium is a highly toxic element that is widespread in the environment from several contamination sources. Consequently, its bioaccumulation through the food chain represents a risk for animal and human health [1,2]. The interactions of Cd with crucial physiological functions in adult plants have been widely investigated [3–7] and drastic diminutions of biomass production and nutritional quality have been observed in crops grown on soils contaminated with this non-essential element [8,9]. Espe- cially, seed germination and subsequent embryo growth are (i) important stages of the plant life and (ii) highly sensitive to sur- rounding medium fluctuations, because the germinating seed is the first interface of material exchange between plant develop- ment cycle and environment [9]. Delay in germination has been often observed after heavy metals exposure [10–15]. This can be associated with disorders in the event chain of germinative metabolism which is a highly complex multistage process, itself co- ordinated by physiological, biochemical and molecular programs [16]. ∗ Corresponding author. Tel.: +216 72 591906; fax: +216 72 590566. E-mail addresses: rahoui.sondes@yahoo.fr (S. Rahoui), cabdelilah1@yahoo.fr (A. Chaoui), ezzferjani2002@yahoo.fr (E. El Ferjani). In the present study, we looked at the ecotoxicological effects of Cd in small scale toxicity tests using seed germination assay of pea (Pisum sativum L.) as a model crop. Pea is also among the most important food crop. It is easily cultured and maintained in the lab- oratory conditions and has been used in toxicity tests to examine the effects of cadmium, especially on the germination of seeds and the growth of early seedlings which are more sensitive to heavy metals [13,15]. This work aimed to explore the effect of cadmium on the aminoacids freeing, as well as the availability of carbohy- drates (soluble sugars, glucose and fructose). The impact of the pollutant on the structural integrity of cell membranes was exam- ined with respect to lipoxygenase activity and malondialdehyde content, major lipid peroxidation product. The electrolyte leakage, estimated through electrical conductivity of germination medium, was investigated to achieve a better understanding of the Cd toxi- city. 2. Material and methods 2.1. Seed germination experiment Seeds of P. sativum L. (cv. douce province) were disinfected in 2% of sodium hypochlorite for 10 min and rinsed thoroughly in distilled water. For one replicate 85 seeds were germinated in the dark at 25 ◦ C over two sheets of filter paper moistened with 60 ml of H 2 O or 5 mM CdCl 2 . The germinating seeds were sampled for the bioassays 0304-3894/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2010.01.115