The National Engineering Research Center for Wheat, Henan Agricultural University, Zhengzhou, 450046, China.
The National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, 450046, China.
Environ Sci Pollut Res Int. 2022 Sep;29(45):68191-68201. doi: 10.1007/s11356-022-20672-6. Epub 2022 May 10.
Cadmium (Cd) is a toxic heavy metal to plants and human health. Ascorbate (ASA)-glutathione (GSH) synthesis pathway plays key roles in Cd detoxification, while its molecular regulatory mechanism remains largely unknown, especially in wheat. Here, we found a WRKY transcription factor-TaWRKY74, and its function in wheat Cd stress is not clear in previous studies. The expression levels of TaWRKY74 were significantly induced by Cd stress. Compared to control, the activities of GST, GR, or APX were significantly increased by 1.55-, 1.43-, or 1.75-fold and 1.63-, 2.65-, or 2.30-fold in shoots and roots of transiently TaWRKY74-silenced wheat plants under Cd stress. Similarly, the contents of hydrogen peroxide (HO), malondialdehyde (MDA), GSH, or Cd were also significantly increased by 2.39- or 1.25-fold, 1.54- or 1.20-fold, and 1.34- or 5.94-fold in shoots or roots in transiently TaWRKY74-silenced wheat plants, while ASA content was decreased by 47.4 or 43.3% in shoots, 10.7 or 6.5% in roots in these silenced wheat plants, respectively. Moreover, the expression levels of GSH, GPX, GR, DHAR, MDHAR, and APX genes, which are involved in ASA-GSH synthesis, were separately induced by 2.42-, 2.16-, 3.28-, 2.08-, 1.92-, and 2.23-fold in shoots, or by 10.69-, 3.33-, 3.26-, 1.81-, 16.53-, and 3.57-fold in roots of the BSMV-VIGS-TaWRKY74-inoculated wheat plants, respectively. However, the expression levels of TaNramp1, TaNramp5, TaHMA2, TaHMA3, TaLCT1, and TaIRT1 metal transporters genes were decreased by 21.2-76.3% (56.6%, 59.2%, 76.3%, 53.6%, 35.8%, and 21.2%) in roots of the BSMV-VIGS-TaWRKY74-inoculated wheat plants. Taken together, our results suggested that TaWRKY74 alleviated Cd toxicity in wheat by affecting the expression of ASA-GSH synthesis genes and suppressing the expression of Cd transporter genes, and further affecting Cd uptake and translocation in wheat plants.
镉（Cd）是一种对植物和人类健康有毒的重金属。抗坏血酸（ASA）-谷胱甘肽（GSH）合成途径在 Cd 解毒中起着关键作用，但其分子调控机制在很大程度上仍然未知，特别是在小麦中。在这里，我们发现了一个 WRKY 转录因子-TaWRKY74，其在小麦 Cd 胁迫下的功能在以前的研究中并不清楚。TaWRKY74 的表达水平在 Cd 胁迫下显著诱导。与对照相比，在 Cd 胁迫下，瞬时沉默 TaWRKY74 的小麦植株的地上部和根部 GST、GR 或 APX 的活性分别增加了 1.55、1.43 或 1.75 倍和 1.63、2.65 或 2.30 倍。同样，在瞬时沉默 TaWRKY74 的小麦植株的地上部或根部，H2O2（HO）、丙二醛（MDA）、GSH 或 Cd 的含量也分别增加了 2.39 或 1.25 倍、1.54 或 1.20 倍和 1.34 或 5.94 倍，而 ASA 含量则分别降低了 47.4 或 43.3%在地上部，10.7 或 6.5%在根部。此外，参与 ASA-GSH 合成的 GSH、GPX、GR、DHAR、MDHAR 和 APX 基因的表达水平分别在瞬时沉默 TaWRKY74 的小麦植株的地上部增加了 2.42、2.16、3.28、2.08、1.92 和 2.23 倍，或在 BSMV-VIGS-TaWRKY74 接种的小麦植株的根部增加了 10.69、3.33、3.26、1.81、16.53 和 3.57 倍。然而，TaNramp1、TaNramp5、TaHMA2、TaHMA3、TaLCT1 和 TaIRT1 金属转运蛋白基因的表达水平在 BSMV-VIGS-TaWRKY74 接种的小麦植株的根部分别降低了 21.2-76.3%（56.6%、59.2%、76.3%、53.6%、35.8%和 21.2%）。综上所述，我们的结果表明，TaWRKY74 通过影响 ASA-GSH 合成基因的表达和抑制 Cd 转运蛋白基因的表达，进而影响小麦植株对 Cd 的吸收和转运，从而减轻 Cd 对小麦的毒性。
