Arsenic toxicity in garden cress ( Lepidium sativum Linn.): significance of potassium nutrition
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RESEARCH ARTICLE
Arsenic toxicity in garden cress (Lepidium sativum Linn.): significance of potassium nutrition Shahid Umar & Nidhi Gauba & Naser A. Anjum & Tariq O. Siddiqi
Received: 11 December 2012 / Accepted: 11 March 2013 / Published online: 26 March 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract In a hydroponic culture, experiments were performed to study the influence of potassium (K) supplementation (0, 20, 40, 60, 80, and 100 mg L−1) on the arsenic (As; 0, 8, and 10 mg L−1)-accrued changes in growth traits (plant biomass, root–shoot length) and the contents of lepidine, As and K, in garden cress (Lepidium sativum Linn.) at 10 days after treatment. The changes in these traits were correlated with shoot proline content, protein profile, and the activities of antioxidant enzymes namely superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione reductase (GR, EC 1.8.1.7), and ascorbate peroxidase (APX, EC 1.11.1. 11). In general, As-alone treatments significantly decreased the growth traits but lead to significant enhancements in shoot proline and enzyme activities. K-supplementation to Astreated L. sativum seedlings decreased shoot-As content, reduced As-induced decreases in growth traits but enhanced the content of shoot proline, and the activities of the studied enzymes maximally with K100 + As8 and As10 mg L−1. Both 8 and 10 mg L−1 of As drastically downregulated the shoot proteins ranging from 43–65 kDa. With As10 mg L−1, there was a total depletion of protein bands below 23 kDa; however, K80 mg L−1 maximally recovered and upregulated the protein bands. Additionally, protein bands were downregulated (at par Responsible editor: Elena Maestri S. Umar (*) : N. Gauba : N. A. Anjum : T. O. Siddiqi Department of Botany, Faculty of Science, Hamdard University, New Delhi 110062, India e-mail: [email protected] N. Gauba Amity School of Engineering and Technology, Amity University Uttar Pradesh (AUUP), Noida, Uttar Pradesh 201301, India N. A. Anjum (*) CESAM-Centre for Environmental and Marine Studies and Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal e-mail: [email protected]
with As-alone treatment) above K80 mg L−1 level. Interestingly, As-stress increased lepidine content in a dose-dependent manner which was further augmented with the K-supplementation. It is suggested that K protects L. sativum against As-toxicity by decreasing its accumulation and strengthening antioxidant defense system and protein stability. Keywords Arsenic . Toxicity . Lepidiumsativum . Lepidine . Amelioration . Potassium
Introduction Arsenic (As) is a naturally occurring metalloid, 20th most abundant element in the earth's crust, and a component of more than 245 minerals. However, human activities have increased the soil concentration of As to levels that exceed hazard thresholds. Soils may contain As-concentrations as low as 0.2 mg kg−1 or as high as 41 mg kg−1 (KabataPendias and Pendias 2001; Moreno-Jiménez et al. 2012). Although at very low concentrations, As can be beneficial fo
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