Contents lists available at ScienceDirect Ecotoxicology and Environmental Safety journal homepage: www.elsevier.com/locate/ecoenv Effect of cadmium on morphometric traits, antioxidant enzyme activity and phytochelatin synthase gene expression (SoPCS) of Saccharum officinarum var. cp48-103 in vitro Z. Yousefi a , M. Kolahi b, ⁎ , A. Majd a , P. Jonoubi a a Department of Plant Sciences, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran b Department of Biology, Faculty of Science, Shahid Chamram University of Ahvaz, Ahvaz, Iran ARTICLE INFO Keywords: Antioxidant enzymes Cadmium SoPCS gene expression Saccharum officinarum ABSTRACT Cadmium is an important environmental pollutant which genetically, physiologically and biochemically affects the cell. Phytochelatins (PC) are involved in one of the phytoremediation mechanisms, in which they are able to bind heavy metals, such as cadmium. The objective of this study was to evaluate morphometric, antioxidant enzyme activity, and SoPCS gene expression in sugarcane growing under cadmium stress. After propagation, samples were cultured in triplicate for 14 days in modified MS medium containing CdCl 2 (100, 250, 500 μmol). The morphometric traits, pigments, quantity and antioxidant enzyme activity were studied in treated plantlets. SoPCS gene expression was analyzed by qRT-PCR. Growth traits decreased following cadmium treatment. The amount of Chl a , Chl b and ChlT decreased in treated samples, whereas carotenoids increased significantly. A rapid increase in antioxidant enzyme activity was detected. Enhanced SoPCS gene expression was observed in treated roots, whereas gene expression pattern in leaves was irregular. In conclusion, cadmium decreases the photo- synthetic mechanism and growth rate in sugarcane. Antioxidative enzymes and SoPCS gene expression were significantly unregulated in sugarcane roots compared to the leaves. Cadmium concentration in shoots and roots of sugarcane significantly increased. The management of cadmium bioaccumulation in non-edible tissues of sugarcane such as leaves and roots that are sometimes burned after harvest can be applied for environmental protection. 1. Introduction Heavy metal pollution has resulted from industrial and technolo- gical activities. Due to their toxicity, nonbiodegradability and inability to biodisintegrate the bio-accumulation of heavy metals poses a serious threat to the environment. The global level of pollution in the past 150 years has increased more than 4000 times. Cadmium as a heavy metal is one of the three most abundant metal pollutants in soil, water, and air. Cadmium is toxic to plants, animals and microorganisms. It can enter the food chain by natural and industrial sources and can accumulate in the kidney or liver of vertebrates. Scientific research has shown that exposure to cadmium over a long time can lead to lung cancer. EPA has categorized cadmium in the B1 Group, which is associated with human carcinogens. According to the FAO and WHO's data, in most countries, the average cadmium intake is 0.7–2.8 μg/kg body weight, weekly (FAO/WHO, 2006). The main sources of cadmium in the environment are smelting, mining, burning of fossil fuels (coal or oil), municipal waste incineration and cigarette smoking. Besides natural cadmium sources, the steel industry and waste incineration as anthropogenic activity release the greatest amount of cadmium. Different physico- chemical strategies for removal of heavy metals from the environment has some disadvantages, such as the need for technical equipment and system refinement, high consumption of energy, lack of economic jus- tification, low performance, incomplete separation of metals and stay of contaminating residues (Guo et al., 2010). Phytoremediation is one of the most secure methods to reduce industrial pollutants in con- taminated soil. The amount of cadmium uptake from the soil by plants is influenced by soil pH, salinity, humus content, crop species and varieties. The cadmium regulatory limit in agricultural soil is 100 mg/ kg soil (Salt et al., 1995). Plants grown in soil having more than 100 mg/kg cadmium show some signs of damage such as chlorosis, growth inhibition, root tip browning and finally death (Sanita di Toppi and Gabbrielli, 1999; Guo et al., 2004; Wojcik and Tukiendorf, 2005). Cadmium can also be interchanged easily through the soil by plant roots, leafy vegetables, root crops, cereals and grains thereby entering the food chain (ATSDR, 1999). https://doi.org/10.1016/j.ecoenv.2018.03.076 Received 2 December 2017; Received in revised form 25 March 2018; Accepted 27 March 2018 ⁎ Corresponding author. E-mail address: m.kolahi@scu.ac.ir (M. Kolahi). Ecotoxicology and Environmental Safety 157 (2018) 472–481 0147-6513/ © 2018 Published by Elsevier Inc. T