title: Citric acid assisted phytoremediation of copper by Brassica napus L.
abstract: Use of organic acids for promoting heavy metals phytoextraction is gaining worldwide attention. The present study investigated the influence of citric acid (CA) in enhancing copper (Cu) uptake by Brassica napus L. seedlings. 6 Weeks old B. napus seedlings were exposed to different levels of copper (Cu, 0, 50 and 100µM) alone or with CA (2.5mM) in a nutrient medium for 40 days. Exposure to elevated Cu levels (50 and 100µM) significantly reduced the growth, biomass production, chlorophyll content, gas exchange attributes and soluble proteins of B. napus seedlings. In addition, Cu toxicity increased the production of hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) in leaf and root tissues of B. napus. Activities of antioxidant enzymes such as guaiacol peroxidase (POD), superoxide dismutase (SOD), catalases (CAT), ascorbate peroxidase (APX) in root and shoot tissues of B. napus were increased in response to lower Cu concentration (50µM) but increased under higher Cu concentration (100µM). Addition of CA into nutrient medium significantly alleviated Cu toxicity effects on B. napus seedlings by improving photosynthetic capacity and ultimately plant growth. Increased activities of antioxidant enzymes in CA-treated plants seems to play a role in capturing of stress-induced reactive oxygen species as was evident from lower level of H2O2, MDA and EL in CA-treated plants. Increasing Cu concentration in the nutrient medium significantly increased Cu concentration in in B. napus tissues. Cu uptake was further increased by CA application. These results suggested that CA might be a useful strategy for increasing phytoextraction of Cu from contaminated soils.
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Ihsan Elahi
authors.initials: IE
authors.lastname: Zaheer
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University Allama Iqbal Road, 38000 Faisalabad, Pakistan. Electronic address: shafaqataligill@yahoo.com.
authors.forename: Shafaqat
authors.initials: S
authors.lastname: Ali
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Rizwan
authors.affiliation: Department of Environmental Sciences, University of Gujrat, Hafiz Hayat Campus, Jalal Put Jattan Road, Gujrat, Pakistan.
authors.forename: Mujahid
authors.initials: M
authors.lastname: Farid
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Muhammad Bilal
authors.initials: MB
authors.lastname: Shakoor
authors.affiliation: Institute of Crop Science and Zhejiang Key Laboratory of Crop Germplasm, Zhejiang University, Hangzhou 310058, China.
authors.forename: Rafaqa Ali
authors.initials: RA
authors.lastname: Gill
authors.affiliation: Department of Plant and Food Sciences, Faculty of Agriculture and Environment, The University of Sydney, Eveleigh, NSW 2015, Australia.
authors.forename: Ullah
authors.initials: U
authors.lastname: Najeeb
authors.affiliation: Department of Botany, Government College University Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Naeem
authors.initials: N
authors.lastname: Iqbal
authors.affiliation: Department of Environmental Sciences and Engineering, Government College University Allama Iqbal Road, 38000 Faisalabad, Pakistan.
authors.forename: Rehan
authors.initials: R
authors.lastname: Ahmad
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism; D001673:Biodegradation, Environmental; D029688:Brassica napus / Q000737:chemistry*; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000032:analysis; D019343:Citric Acid / Q000494:pharmacology*; D003300:Copper / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000737:chemistry / Q000187:drug effects; D018517:Plant Roots / Q000737:chemistry / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D002734:Chlorophyll; D019343:Citric Acid; D008315:Malondialdehyde; D003300:Copper; D006861:Hydrogen Peroxide; C121048:guaiacol peroxidase; D060387:Ascorbate Peroxidases; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase
keywords: Antioxidant enzymes; Brassica napus L.; Citric acid; Copper; Oxidative stress; Phytoextraction