Phenotypical, physiological and biochemical analyses provide insight into selenium-induced phytotoxicity in rice plants.
The present study investigated the phenotypical, physiological and biochemical changes of rice plants exposed to high selenium (Se) concentrations to gain an insight into Se-induced phytotoxicity. Results showed that exposure of rice plants to excessive Se resulted in growth retardation and biomass reduction in connection with the decreased levels of chlorophyll, carotenoids and soluble proteins. The reduced water status and an associated increase in sugar and proline levels indicated Se-induced osmotic stress in rice plants. Measurements of Se contents in roots, leaf sheaths and leaves revealed that Se was highly accumulated in leaves followed by leaf sheaths and roots. Se also potentiated its toxicity by impairing oxidative metabolism, as evidenced by enhanced accumulation of hydrogen peroxide, superoxide and lipid peroxidation product. Se toxicity also displayed a desynchronized antioxidant system by elevating the level of glutathione and the activities of superoxide dismutase, glutathione-S-transferase and glutathione peroxidase, whereas decreasing the level of ascorbic acid and the activities of catalase, glutathione reductase and dehydroascorbate reductase. Furthermore, Se triggered methylglyoxal toxicity by inhibiting the activities of glyoxalases I and II, particularly at higher concentrations of Se. Collectively, our results suggest that excessive Se caused phytotoxic effects on rice plants by inducing chlorosis, reducing sugar, protein and antioxidant contents, and exacerbating oxidative stress and methylglyoxal toxicity. Accumulation levels of Se, proline and glutathione could be considered as efficient biomarkers to indicate degrees of Se-induced phytotoxicity in rice, and perhaps in other crops.
Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan; Department of Biochemistry and Molecular Biology, Bangabandhu Shiekh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh.
Mohammad Golam
MG
Mostofa
Department of Genetics and Plant Breeding, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh.
Mohammad Anwar
MA
Hossain
Department of Biochemistry and Molecular Biology, Bangabandhu Shiekh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh.
Md Nurealam
MN
Siddiqui
Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan. Electronic address: fujita@ag.kagawa-u.ac.jp.
Masayuki
M
Fujita
Plant Abiotic Stress Research Group & Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Viet Nam; Signaling Pathway Research Unit, RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan. Electronic address: sontran@tdt.edu.vn.
Lam-Son
LS
Tran
D000975:Antioxidants / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D018533:Biomass; D005978:Glutathione / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D012275:Oryza / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D009997:Osmotic Pressure / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D018514:Plant Structures / Q000737:chemistry; D011392:Proline / Q000378:metabolism; D012643:Selenium / Q000032:analysis / Q000633:toxicity*
D000975:Antioxidants; D015415:Biomarkers; D011392:Proline; D005978:Glutathione; D012643:Selenium
Oxidative metabolism; Physiological and biochemical mechanisms; Phytotoxic effects; Selenium homeostasis