Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
Key Laboratory of Tropical Agro-Environment, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China.
Int J Environ Res Public Health. 2018 Oct 8;15(10):2193. doi: 10.3390/ijerph15102193.
Silicon (Si) plays important roles in alleviating heavy metal stress in rice plants. Here we investigated the physiological response of rice at different growth stages under the silicon-induced mitigation of cadmium (Cd) and zinc (Zn) toxicity. Si treatment increased the dry weight of shoots and roots and reduced the Cd and Zn concentrations in roots, stems, leaves and grains. Under the stress of exposure to Cd and Zn, photosynthetic parameters including the chlorophyll content and chlorophyll fluorescence decreased, while the membrane permeability and malondialdehyde (MDA) increased. Catalase (CAT) and peroxidase (POD) activities increased under heavy metals stress, but superoxide dismutase (SOD) activities decreased. The magnitude of these Cd- and Zn-induced changes was mitigated by Si-addition at different growth stages. The available Cd concentration increased in the soil but significantly decreased in the shoots, which suggested that Si treatment prevents Cd accumulation through internal mechanisms by limiting Cd uptake by the roots. Overall, the phenomena of Si-mediated alleviation of Cd and excess Zn toxicity in two rice cultivars could be due to the limitation of metal uptake and transport, resulting in an improvement in cell membrane integrity, photosynthetic performance and anti-oxidative enzyme activities after Si treatment.
硅（Si）在缓解水稻植物中重金属胁迫方面起着重要作用。在这里，我们研究了在硅缓解镉（Cd）和锌（Zn）毒性的作用下，不同生长阶段的水稻的生理响应。Si 处理增加了地上部和根部的干重，降低了根部、茎部、叶片和籽粒中的 Cd 和 Zn 浓度。在暴露于 Cd 和 Zn 胁迫下，包括叶绿素含量和叶绿素荧光在内的光合作用参数下降，而膜通透性和丙二醛（MDA）增加。在重金属胁迫下，过氧化氢酶（CAT）和过氧化物酶（POD）活性增加，而过氧化物歧化酶（SOD）活性降低。在不同的生长阶段添加 Si 可以减轻这些 Cd 和 Zn 引起的变化。土壤中的有效 Cd 浓度增加，但地上部的 Cd 浓度显著降低，这表明 Si 处理通过限制根对 Cd 的吸收，通过内部机制防止 Cd 积累。总的来说，两种水稻品种中 Si 介导的 Cd 和过量 Zn 毒性缓解现象可能是由于金属吸收和转运的限制，导致 Si 处理后细胞膜完整性、光合作用性能和抗氧化酶活性得到改善。
