Resources and Environment College, Henan Agricultural University, No. 63, Nongye Road, Jinshui District, Zhengzhou, 450002, Henan Province, China.
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409, USA.
BMC Plant Biol. 2020 Dec 7;20(1):550. doi: 10.1186/s12870-020-02763-z.
Cadmium (Cd) accumulation in crops affects the yield and quality of crops and harms human health. The application of selenium (Se) can reduce the absorption and transport of Cd in winter wheat.
The results showed that increasing Se supply significantly decreased Cd concentration and accumulation in the shoot and root of winter wheat and the root-to-shoot translocation of Cd. Se application increased the root length, surface area and root volume but decreased the average root diameter. Increasing Se supply significantly decreased Cd concentration in the cell wall, soluble fraction and cell organelles in root and shoot. An increase in Se supply inhibited Cd distribution in the organelles of shoot and root but enhanced Cd distribution in the soluble fraction of shoot and the cell wall of root. The Se supply also decreased the proportion of active Cd (ethanol-extractable (FE) Cd and deionized water-extractable (FW) Cd) in root. In addition, the expression of TaNramp5-a, TaNramp5-b, TaHMA3-a, TaHMA3-b and TaHMA2 significantly increased with increasing Cd concentration in root, and the expression of TaNramp5-a, TaNramp5-b and TaHMA2 in root was downregulated by increasing Se supply, regardless of Se supply or Cd stress. The expression of TaHMA3-b in root was significantly downregulated by 10 μM Se at both the 5 μM and 25 μM Cd level but upregulated by 5 μM Se at the 25 μM Cd level. The expression of TaNramp5-a, TaNramp5-b, TaHMA3-a, TaHMA3-b and TaHMA2 in shoot was downregulated by increasing Se supply at 5 μM Cd level, and 5 μM Se upregulated the expression of those genes in shoot at 25 μM Cd level.
The results confirm that Se application limits Cd accumulation in wheat by regulating the subcellular distribution and chemical forms of Cd in winter wheat tissues, as well as the expression of TaNramp5-a, TaNramp5-b and TaHMA2 in root.
镉（Cd）在作物中的积累会影响作物的产量和质量，危害人类健康。施用硒（Se）可以减少冬小麦对 Cd 的吸收和运输。
结果表明，增加 Se 供应显著降低了冬小麦地上部和根部 Cd 的浓度和积累，以及 Cd 的根-茎转运。Se 处理增加了根长、表面积和根体积，而降低了平均根直径。增加 Se 供应显著降低了根和地上部细胞壁、可溶部分和细胞器中 Cd 的浓度。增加 Se 供应抑制了 Cd 在地上部和根部细胞器中的分布，但增加了 Cd 在地上部可溶部分和根部细胞壁中的分布。Se 供应还降低了根中活性 Cd（乙醇提取（FE）Cd 和去离子水提取（FW）Cd）的比例。此外，随着根中 Cd 浓度的增加，TaNramp5-a、TaNramp5-b、TaHMA3-a、TaHMA3-b 和 TaHMA2 的表达显著增加，而无论 Se 供应或 Cd 胁迫如何，根中 TaNramp5-a、TaNramp5-b 和 TaHMA2 的表达均受 Se 供应的下调。在 5 μM 和 25 μM Cd 水平下，10 μM Se 显著下调了根中 TaHMA3-b 的表达，但在 25 μM Cd 水平下，5 μM Se 上调了根中 TaHMA3-b 的表达。在 5 μM Cd 水平下，增加 Se 供应下调了地上部 TaNramp5-a、TaNramp5-b、TaHMA3-a、TaHMA3-b 和 TaHMA2 的表达，而在 25 μM Cd 水平下，5 μM Se 上调了地上部这些基因的表达。
结果证实，Se 处理通过调节冬小麦组织中 Cd 的亚细胞分布和化学形态，以及根中 TaNramp5-a、TaNramp5-b 和 TaHMA2 的表达，限制了小麦对 Cd 的积累。
