Hasanuzzaman Mirza, Alam Md Mahabub, Nahar Kamrun, Mohsin Sayed Mohammad, Bhuyan M H M Borhannuddin, Parvin Khursheda, Hawrylak-Nowak Barbara, Fujita Masayuki
Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, 1207, Bangladesh.
Department of Agriculture, Faculty of Science, Noakhali Science and Technology University, Noakhali, 3814, Bangladesh.
Ecotoxicology. 2019 Apr;28(3):261-276. doi: 10.1007/s10646-019-02019-z. Epub 2019 Feb 13.
Nickel (Ni), an essential nutrient of plant but very toxic to plant at supra-optimal concentration that causes inhibition of seed germination emergence and growth of plants as a consequence of physiological disorders. Hence, the present study investigates the possible mechanisms of Ni tolerance in rice seedlings by exogenous application of silicon (Si). Thirteen-day-old hydroponically grown rice (Oryza sativa L. cv. BRRI dhan54) were treated with Ni (NiSO.7HO, 0.25 and 0.5 mM) sole or in combination with 0.50 mM NaSiO for a period of 3 days to investigate the effect of Si supply for revoking the Ni stress. Nickel toxicity gave rise to reactive oxygen species (ROS) and cytotoxic methylglyoxal (MG), accordingly, initiated oxidative stress in rice leaves, and accelerated peroxidation of lipids and consequent damage to membranes. Reduced growth, biomass accumulation, chlorophyll (chl) content, and water balance under Ni-stress were also found. However, free proline (Pro) content increased in Ni-exposed plants. In contrast, the Ni-stressed seedlings fed with supplemental Si reclaimed the seedlings from chlorosis, water retrenchment, growth inhibition, and oxidative stress. Silicon up-regulated most of the antioxidant defense components as well as glyoxalase systems, which helped to improve ROS scavenging and MG detoxification. Hence, these results suggest that the exogenous Si application can improve rice seedlings' tolerance to Ni-toxicity.
镍（Ni）是植物的一种必需营养素，但在超最佳浓度时对植物具有剧毒，由于生理紊乱，会导致种子发芽、出苗和植物生长受到抑制。因此，本研究通过外源施用硅（Si）来探究水稻幼苗耐镍的可能机制。对水培生长13天的水稻（Oryza sativa L. cv. BRRI dhan54）单独用镍（NiSO₄·7H₂O，0.25和0.5 mM）处理，或与0.50 mM的Na₂SiO₃联合处理3天，以研究硅供应对缓解镍胁迫的影响。镍毒性会产生活性氧（ROS）和细胞毒性甲基乙二醛（MG），相应地，会引发水稻叶片的氧化应激，并加速脂质过氧化以及随之而来的膜损伤。还发现镍胁迫下生长、生物量积累、叶绿素（chl）含量和水分平衡降低。然而，镍处理植株中游离脯氨酸（Pro）含量增加。相比之下，补充硅的镍胁迫幼苗从黄化、水分减少、生长抑制和氧化应激中恢复过来。硅上调了大多数抗氧化防御成分以及乙二醛酶系统，这有助于改善ROS清除和MG解毒。因此，这些结果表明外源施用硅可以提高水稻幼苗对镍毒性的耐受性。
