American Journal of Plant Sciences, 2015, 6, 2906-2923 Published Online November 2015 in SciRes. http://www.scirp.org/journal/ajps http://dx.doi.org/10.4236/ajps.2015.618287 How to cite this paper: Kanwal, S., Bano, A. and Malik, R.N. (2015) Effects of Arbuscular Mycorrhizal Fungi on Metals Up- take, Physiological and Biochemical Response of Medicago Sativa L. with Increasing Zn and Cd Concentrations in Soil. American Journal of Plant Sciences, 6, 2906-2923. http://dx.doi.org/10.4236/ajps.2015.618287 Effects of Arbuscular Mycorrhizal Fungi on Metals Uptake, Physiological and Biochemical Response of Medicago Sativa L. with Increasing Zn and Cd Concentrations in Soil Sadia Kanwal * , Asma Bano, Riffat Naseem Malik Environmental Biology and Ecotoxicology Laboratory, Department of Environmental Sciences, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan Email: * skkanwal7@gmail.com Received 29 September 2015; accepted 20 November 2015; published 24 November 2015 Copyright © 2015 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract The effect of mycorrhizal symbiosis on metal accumulation and plant tolerance are not commonly studied in medicinal plants under metal stress. The objective of this study was to assess the impact of mycorrhiza on alfalfa plants with the increase of Zn and Cd toxicity. The experiment was con- ducted under controlled laboratory conditions. Zinc (Zn) and cadmium (Cd) uptake, some bio- chemical and physiological parameters were studied in eight-week-old alfalfa plants in response to inoculation or not with arbuscular mycorrhizal fungi (AMF) and with the increase of Zn (0, 100, 300, 900 mg∙kg −1 ) and Cd concentrations (0, 100, 300, 600 mg∙kg −1 ) in soil. The results showed that mycorrhizal (M) plants exhibited tolerance to Zn and Cd up to 300 mg∙kg −1 in comparison to non-mycorrhizal (NM) plants which exhibited a significant growth reduction at the same soil Zn and Cd level. M inoculation reduced the Zn and Cd accumulation in shoot and showed higher Zn and Cd contents in roots which showed a different Zn and Cd distribution in AMF associated or non-associated plants. Mycorrhizal plants increased phosphorus (P) contents at all Zn and Cd concentrations except the highest (600 and 900 mg∙kg −1 ) leading significant alterations in bio- chemical contents such as proline, antioxidant enzymes in leaves and also in nutrients (N, P, K, Cu, Ni, Fe, Mn). Zn and cadmium toxicity cause to increase the proline content in shoot of NM plants, however, proline contents are lower in M plants. Results confirmed that AMF protected alfalfa plants against Zn and Cd toxicity. Mycorrhizal colonization was able to form an efficient symbiosis with alfalfa plants in moderately contaminated Zn and Cd soils (300 mg∙kg −1 ) and play an impor- tant role in food quality and safety. * Corresponding author.