Lead (Pb) bioaccumulation and antioxidative responses in Tetraena qataranse

• Published in: Scientific reports 2020-10, Vol.10 (1), p.17070, Article 17070
• Main Authors: Usman, Kamal, Abu-Dieyeh, Mohammed H., Zouari, Nabil, Al-Ghouti, Mohammad A.
• Format: Article
• Language: English
• Subjects: 631/449/2661/2665; 704/158/2455; Antioxidants - metabolism; Ascorbate Peroxidases - metabolism; Bioaccumulation; Biodegradation, Environmental; Catalase - metabolism; Glutathione Reductase - metabolism; Humanities and Social Sciences; Humans; Lead - pharmacokinetics; Lead - toxicity; multidisciplinary; Peroxidase - metabolism; Plant Proteins - metabolism; Qatar; Science; Science (multidisciplinary); Soil Pollutants - pharmacokinetics; Soil Pollutants - toxicity; Superoxide Dismutase - metabolism; Zygophyllaceae - drug effects; Zygophyllaceae - growth & development; Zygophyllaceae - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-73621-z

Lead (Pb) is the second most toxic metal on Earth and is toxic to humans and other living things. In plants, Pb commonly inhibits growth when it is at a concentration in the soil of 30 mg/kg or more but several Pb tolerant plants have been reported. However, few studies have focused on plant response to Pb exposure, particularly at concentrations higher than 30 mg/kg. The assessment and evaluation of metal dose-dependent plant responses will assist in future phytoremediation studies. Therefore, this work documents the Pb concentration-dependent antioxidative response in Tetraena qataranse. Young seedlings were irrigated with 0, 25, 50, and 100 mg/L Pb every 48 h for seven weeks under greenhouse conditions. A phytotoxicity test showed that at the lowest treatment concentration, Pb stimulates growth. However, at 100 mg/L (1600 mg/kg Pb in the growth medium at harvest), the metal disrupted healthy growth in T. qataranse , particularly root development. Metal accumulation in the root was higher (up to 2784 mg/kg) than that of the shoot (1141.6 mg/kg). Activity assays of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and glutathione reductase (GR) showed a progressive increase in enzymatic activities due to Pb treatment. Together, the results of this study suggest that T. qataranse is a Pb hyperaccumulator. Increased antioxidant enzyme activity was essential to maintaining cellular homeostasis and assisted in the arid plant’s tolerance to Pb stress.