Exogenous silicon alleviates cadmium toxicity in rice seedlings in relation to Cd distribution and ultrastructure changes
Exogenous silicon alleviates cadmium toxicity in rice seedlings in relation to Cd distribution and ultrastructure changes
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外源硅减轻水稻幼苗镉毒性与镉分布和超微结构变化的关系
DOI：
10.1007/s11368-017-1902-2
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发表时间：
2018-04-01
影响因子：
3.6
通讯作者：
Liu, Mingda
中科院分区：
文献类型：
--
作者：
Guo, Lei;Chen, Aiting;Liu, Mingda
目的硅对水稻镉毒害具有抑制作用，但含硅材料对水培基质化学性质的影响一直被忽视。当使用碱性试剂时，增加的pH值和过量阳离子的引入可能掩盖Si的真实功能。因此，本研究调查硅缓解镉毒害水稻幼苗，通过消除上述interference.Materials和方法的水培水稻幼苗进行，以证明外源硅对镉积累和分配的抑制作用。测定了镉胁迫下叶片细胞叶绿素和类胡萝卜素含量。利用透射电镜研究了不同镉胁迫和硅处理条件下水稻叶肉细胞、叶绿体和线粒体的超微结构变化。用硝酸中和Si源的碱度，并通过添加硝酸钠消除Na+水平的差异，以不同的treatment.Results和discussionToxicitySymptoms下的水稻幼苗镉（5毫克L-1）处理后35天，观察到毒性症状，生物量，叶绿素和类胡萝卜素含量降低。添加120 mg L-1 Si后，这些指数的水平有所增加。生物富集系数和转运系数表明，Si降低了Cd在水稻体内的积累量，降低了Cd从根向地上部的转运率，有效地缓解了Cd的毒害。硅的积极作用主要体现在恢复基粒片层和叶绿体膜结构，恢复膜形态和线粒体嵴的数量增加。结论外源硅降低了水稻幼苗特别是地上部对Cd的吸收，抑制了Cd向地上部的转运。此外，硅恢复叶绿体的功能，由于减少脂质过氧化作用。施硅后，镉毒害减轻的部分原因是叶绿体生物合成的改善和镉生物有效性的降低。
PurposeSilicon (Si) has inhibitory effects on cadmium (Cd) toxicity in rice, but the effects of Si-containing materials on the chemical properties of hydroponic media have been ignored. The increased pH value and introduction of excess cations when utilizing alkaline reagents may disguise the true function of the Si. Thus, the present study investigated Si-alleviated effect on Cd toxicity in rice seedlings by eliminating the aforementioned interferences.Materials and methodsThe hydroponic cultivation of rice seedlings was carried out to demonstrate the inhibiting effects of exogenous Si on Cd accumulation and distribution. The chlorophyll and carotenoid contents in leaf cells under Cd stress were also measured. Transmission electron microscopy was used to investigate ultrastructural changes in rice mesophyll cells, chloroplasts, and mitochondria under different Cd-stressed and Si-amended conditions. The alkalinity of the Si source was neutralized with nitric acid, and discrepancies in Na+levels was eliminated by the addition of sodium nitrate to different treatments.Results and discussionToxicity symptoms were observed in rice seedlings under Cd (5 mg L−1) treatment after 35 days, and the biomass, and chlorophyll and carotenoid contents, were lowered. The levels of these indices increased after adding 120 mg L−1Si. The bioconcentration and translocation factor values indicated that Si reduced Cd accumulation in rice plants and also decreased the ratio of Cd translocation from roots to shoots, which effectively alleviated the Cd toxicity. The positive effects of Si were mainly reflected in the recovery of grana lamellae and membrane structures in chloroplasts, and restored membrane morphology and increased numbers of cristae in mitochondria.ConclusionsExogenous Si reduced Cd uptake in rice seedlings, especially in shoots, and inhibited Cd transport into aboveground parts. In addition, Si restored the functions of chloroplasts owing to a decrease in lipid peroxidation. The application of Si indicated that Cd toxicity is alleviated partly because of the improvement in chloroplast biosynthesis and the diminution of Cd bioavailability.