Abstract
ABSTRACTIn this study, the effects of calcium (Ca2+) application on acquired systemic tolerance mechanism to cadmium (Cd) stress in sesame (Sesamum indicum L.) were studied. The Cd stress reduced the root and shoot growth of sesame, and plant contents of photosynthetic pigments; however, the application of Ca2+ improved these parameters under Cd stress condition. The hydrogen peroxide, malondialdehyde and soluble sugar contents were higher under Cd stress, and were reduced by Ca2+ treatment. The antioxidant enzyme activities in the leaves of sesame, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) were higher under Cd stress, whereas reduced concentration was observed in Ca2+-treated plants. Cd stress increased the contents of diacylglycerol and sterol ester; however Ca2+ treatment resulted in a significant increase in phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylserine. Our results indicated that application of calcium enables sesame plants to withstand the deleterious impact of cadmium through upregulating acquired systemic tolerance system as lipid fractions (galactolipids, phospholipids, neutral lipids), antioxidant enzymes (SOD, POD, CAT, APX, GR) hence protect membrane functions.
Highlights
Cadmium stress is among the important abiotic factors that restrict plant growth
The response of sesame to cadmium stress was studied in pot experiments
The results showed that cadmium stress reduced the length of the root and shoot of sesame by
Summary
Cadmium stress is among the important abiotic factors that restrict plant growth. Its uptake by plants is rather quick because of its high mobility, which is, in turn, responsible for its rapid transportation to above-ground plant parts (Asgher et al 2014). The uptake and subsequent accumulation of Cd in plant tissues result in the production of excess reactive oxygen species (ROS), which can obstruct the absorption of essential elements such as zinc, calcium and iron from proteins and inhibit the chloroplast and mitochondrial electron transport chain (Gallego et al 2012). Cadmium induces cell death by exerting oxidative damage on membranes, proteins and nucleic acids, thereby restricting the growth and yield of plants (Nazar et al 2012). It has negative effects on membranes by inducing alterations in the lipid composition. It has been observed that stress-induced alterations in membrane compositions might have both adaptive and deleterious effects on the overall physiological performance of a plant (Mansour & Salama 2004)
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