Plant Science 167 (2004) 1171–1181 Genotypic variation in phytoremediation potential of Brassica juncea cultivars exposed to Cd stress S. Qadir a , M.I. Qureshi a , S. Javed b , M.Z. Abdin a,∗ a Centre for Biotechnology Jamia Hamdard, New Delhi 110062, India b Department of Biochemistry, Jamia Hamdard, New Delhi 110062, India Received 31 July 2003; accepted 18 June 2004 Available online 14 July 2004 Abstract Problem of heavy metal contamination in agricultural lands, in part, is responsible for limiting the crop productivity. In India, Brassica juncea is cultivated as a major oilseed crop. This crop may further be useful in soil reclamation through the process of phytoremediation including phytoextraction of toxic heavy metals such as Zn, Pb, Cd, etc. from the soil. However, selection of B. juncea cultivar (cv.) with high Cd-extraction potential amongst the higher yielding cultivars would be of great importance to reclaim the soil with lesser impact on plant metabolism and hence the yield. Ten such B. juncea cultivars (V 1 –V 10 ) commonly grown in India were selected for the present study to determine their Cd extraction potential and degree of resistance to Cd stress. Ten-day-old seedlings of B. juncea cultivars were exposed to various levels of cadmium chloride (0.0–2.0 mM) for 72 h in hydroponics culture and leaf samples were analyzed at 24, 48 and 72 h after treatment (HAT) for the changes in the rate of lipid peroxidation, plant length, biomass accumulation, cadmium accumulation and activities of catalase (CAT, 1.11.1.6), superoxide dismutase (SOD, 1.15.1.1), ascorbate peroxidase (APX, 1.11.1.11) and glutathione reductase (GR, 1.6.4.2) along with ascorbate (Asc) and glutathione contents. A reduction in the plant length, biomass accumulation, CAT activity and ascorbate content was noted in all the cultivars, however, a significant increase in lipid peroxidation rate, Cd accumulation, activities of APX, GR, SOD and glutathione content was observed. B. juncea cv. Pusa Jai Kisan (V 5 ) showed the least increase in the rate of lipid peroxidation but accumulated highest levels of biomass, Cd and glutathione contents among the cultivars studied. These results indicate that cv. Pusa Jai Kisan possesses a better Cd-sequestering and antioxidant system. High increase in the levels of glutathione suggests its possible incorporation in synthesis of the phytochelatins and metallothioneins to sequester Cd and combat Cd-stress. © 2004 Elsevier Ireland Ltd. All rights reserved. Keywords: Asc–Glu cycle; Cadmium; Oxidative stress; Phytoremediation 1. Introduction Cadmium (Cd) is the fifth most toxic metal to vertebrates and the fourth most toxic metal to vascular plants [1]. Even at low concentration, Cd may adversely affect the plant re- production by inhibiting pollen germination and tube growth [2]. Various authors reported and reviewed the toxic ef- Abbreviations: APX, ascorbate peroxidase; Asc, ascorbate; CAT, cata- lase; Cd, cadmium; DDW, double distilled water; DHAsc, dehydroascor- bate; GR, glutathione reductase; GSH, reduced glutathione; GSSG, oxidized glutathione; MDA, malondialdehyde; ROS, reactive oxygen species; SOD, superoxide dismutase; TBARS, thiobarbituric acid reactive substances ∗ Corresponding author. Tel.: +91-11-26059688x5583; fax: +91-11-26059663. E-mail address: mzabdin@rediffmail.com (M.Z. Abdin). fect of cadmium on biological systems [3–9]. In plants, the symptoms of cadmium-toxicity are easily identifiable rang- ing from slight injury to lethality or crop failure. The most general symptoms are stunting growth, chlorosis and alter- ation of anatomical, morphological, physiological and bio- chemical properties of leaf, stem and roots [10–15]. One of the major consequences of Cd toxicity is oxidative stress [16–19] mediated by increased levels of reactive oxy- gen species (ROS), but in contrast with other heavy metals, such as Cu, it does not seem to act directly on the production of ROS through Fenton-type reactions or Haber–Weiss reac- tions [20]. Evidence that Cd causes the production of ROS [21] in plants came from observations where new isozymes of peroxidases were detected in both root and leaves of Phaseolus vulgaris [22] treated by Cd. Further evidence of the Cd-induced oxidative stress was obtained from the 0168-9452/$ – see front matter © 2004 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.plantsci.2004.06.018