Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China.
Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China.
Environ Pollut. 2023 Sep 15;333:122046. doi: 10.1016/j.envpol.2023.122046. Epub 2023 Jun 18.
Cadmium (Cd) pollution endangers the safe utilization of paddy soils, and foliar zinc (Zn) can reduce the toxic effects of Cd. However, little is known about the effects of foliar Zn application on the transport and immobilization of Cd in key rice tissues and the physiological state of rice plants. A pot experiment was conducted to explore the effects of spraying 0.2% and 0.4% Zn (ZnSO) during the early grain-filling stage on Cd transport in rice, photosynthesis, glutathione (GSH) levels, Cd concentrations in xylem sap, and the expression of Zn transporter genes. The results showed that grain Cd concentrations in the 0.2% Zn and 0.4% Zn treatments were 24% and 31% lower, respectively, than those of the control treatments at maturity. Compared with the control treatments, the 0.4% Zn treatment increased Cd by 60%, 69%, 23%, and 22% in husks, rachises, first internodes, and roots, respectively. Application of Zn reduced xylem Cd content by up to 26% and downregulated transporter genes (OSZIP12, OSZIP4, and OSZIP7a) in flag leaves. Foliar Zn increased Cd bioaccumulation in roots while decreasing Cd bioaccumulation in grains. Zn reduced GSH concentration in flag leaves and stems, inhibiting photosynthesis (intercellular CO concentration, transpiration rate). Taken together, foliar Zn can reduce the expression of Zn transporter genes and the mobility of Cd in the xylem, promoting the fixation of Cd in husks, rachises, first internodes, and roots, ultimately reducing Cd concentration in rice grains.
镉（Cd）污染危及稻田的安全利用，叶面锌（Zn）可以减轻 Cd 的毒性。然而，人们对叶面 Zn 喷施在关键水稻组织中 Cd 迁移和固定以及水稻植株生理状态的影响知之甚少。本研究采用盆栽试验，探讨了在灌浆早期喷施 0.2%和 0.4% ZnSO4 对水稻 Cd 迁移、光合作用、谷胱甘肽（GSH）水平、木质部汁液中 Cd 浓度以及 Zn 转运体基因表达的影响。结果表明，在成熟时，0.2% Zn 和 0.4% Zn 处理的籽粒 Cd 浓度分别比对照处理低 24%和 31%。与对照处理相比，0.4% Zn 处理使稻壳、稻穗、第一节间和根中 Cd 含量分别增加了 60%、69%、23%和 22%。Zn 的施用可使木质部 Cd 含量降低 26%，并下调旗叶中的转运体基因（OSZIP12、OSZIP4 和 OSZIP7a）。叶面 Zn 增加了根部 Cd 的生物积累，同时减少了籽粒中的 Cd 生物积累。Zn 降低了旗叶和茎中的 GSH 浓度，抑制了光合作用（胞间 CO2 浓度、蒸腾速率）。总之，叶面 Zn 可以降低 Zn 转运体基因的表达和木质部 Cd 的迁移性，促进 Cd 在稻壳、稻穗、第一节间和根中的固定，最终降低稻米中 Cd 的浓度。
