Mostofa Mohammad Golam, Hossain Mohammad Anwar, Siddiqui Md Nurealam, Fujita Masayuki, Tran Lam-Son
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.
Department of Genetics and Plant Breeding, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh.
Chemosphere. 2017 Jul;178:212-223. doi: 10.1016/j.chemosphere.2017.03.046. Epub 2017 Mar 11.
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.
本研究调查了暴露于高硒（Se）浓度下水稻植株的表型、生理和生化变化，以深入了解硒诱导的植物毒性。结果表明，水稻植株暴露于过量硒会导致生长迟缓、生物量减少，同时叶绿素、类胡萝卜素和可溶性蛋白质水平降低。水分状况降低以及糖和脯氨酸水平相应增加表明硒诱导了水稻植株的渗透胁迫。对根、叶鞘和叶片中硒含量的测量表明，硒在叶片中高度积累，其次是叶鞘和根。硒还通过损害氧化代谢增强其毒性，过氧化氢、超氧化物和脂质过氧化产物积累增加证明了这一点。硒毒性还通过提高谷胱甘肽水平以及超氧化物歧化酶、谷胱甘肽-S-转移酶和谷胱甘肽过氧化物酶的活性，使抗氧化系统失调，而抗坏血酸水平以及过氧化氢酶、谷胱甘肽还原酶和脱氢抗坏血酸还原酶的活性降低。此外，硒通过抑制乙二醛酶I和II的活性引发甲基乙二醛毒性，尤其是在较高硒浓度下。总体而言，我们的结果表明，过量硒通过诱导黄化、降低糖、蛋白质和抗氧化剂含量以及加剧氧化应激和甲基乙二醛毒性，对水稻植株产生了植物毒性作用。硒、脯氨酸和谷胱甘肽的积累水平可被视为指示水稻以及可能其他作物中硒诱导的植物毒性程度的有效生物标志物。
