A stress-associated protein, LmSAP, from the halophyte Lobularia maritima provides tolerance to heavy metals in tobacco through increased ROS scavenging and metal detoxification processes

• Published in: Journal of plant physiology 2018-12, Vol.231, p.234-243
• Main Authors: Saad, Rania Ben, Hsouna, Anis Ben, Saibi, Walid, Hamed, Karim Ben, Brini, Faical, Ghneim-Herrera, Thaura
• Format: Article
• Language: English
• Subjects: Agricultural land; Agricultural pollution; Antioxidants; Brassicaceae - genetics; Brassicaceae - metabolism; Brassicaceae - physiology; Cadmium; Catalase; Copper; Cytosol; Detoxification; Genes, Plant - genetics; Halophytes; Heavy metal tolerance; Heavy metals; Hydrogen peroxide; Lipid peroxidation; Lipids; LmSAP gene; Lobularia maritima; Manganese; Metal accumulation; Metal concentrations; Metallothioneins; Metals; Metals, Heavy - toxicity; Nicotiana - genetics; Nicotiana - metabolism; Nicotiana - physiology; Oxidative Stress; Peroxidase; Peroxidation; Plant cells; Plant protection; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Proteins - physiology; Plants, Genetically Modified; Protein transport; Proteins; Reactive oxygen species; Reactive Oxygen Species - metabolism; Real-Time Polymerase Chain Reaction; Salt-Tolerant Plants - genetics; Salt-Tolerant Plants - metabolism; Scavenging; Seedlings; Soil Pollutants - toxicity; Soil pollution; Superoxide dismutase; Survival; Tobacco; Transcription; Transgenic plants; Ubiquitin; Zinc
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2018.09.019

Agricultural soil pollution by heavy metals is a severe global ecological problem. We recently showed that overexpression of LmSAP, a member of the stress-associated protein (SAP) gene family isolated from Lobularia maritima, in transgenic tobacco led to enhanced tolerance to abiotic stress. In this study, we characterised the response of LmSAP transgenic tobacco plants to metal stresses (cadmium (Cd), copper (Cu), manganese (Mn), and zinc (Zn)). In L. maritima, LmSAP expression increased after 12 h of treatment with these metals, suggesting its involvement in the plant response to heavy metal stress. LmSAP transgenic tobacco plants subjected to these stress conditions were healthy, experienced higher seedling survival rates, and had longer roots than non-transgenic plants (NT). However, they exhibited higher tolerance towards cadmium and manganese than towards copper and zinc. LmSAP-overexpressing tobacco seedlings accumulated more cadmium, copper, and manganese compared with NT plants, but displayed markedly decreased hydrogen peroxide (H2O2) and lipid peroxidation levels after metal treatment. Activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were significantly higher in transgenic plants than in NT plants after exposure to metal stress. LmSAP overexpression also enhanced the transcription of several genes encoding metallothioneins (Met1, Met2, Met3, Met4, and Met5), a copper transport protein CCH, a Cys and His-rich domain-containing protein RAR1 (Rar1), and a ubiquitin-like protein 5 (PUB1), which are involved in metal tolerance in tobacco. Our findings indicate that LmSAP overexpression in tobacco enhanced tolerance to heavy metal stress by protecting the plant cells against oxidative stress, scavenging reactive oxygen species (ROS), and decreasing the intracellular concentration of free heavy metals through its effect on metal-binding proteins in the cytosol.