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【目的】研究持续淹水对不同镉(Cadmium,Cd)积累水稻品种Cd含量的影响,通过分析持续淹水条件下土壤有效性Cd、植株Cd含量以及水稻根系Cd吸收转运关键基因表达,揭示持续淹水对水稻Cd积累的作用及其调控机制。【方法】采用水稻品种辐品36(FP36,Cd高积累品种)和中嘉早17(ZJZ17,Cd低积累品种),盆栽条件下(外源加入1.5 mg·kg-1 Cd Cl2)于水稻分蘖始期开始持续淹水处理,分蘖盛期取样分析植株Cd含量及Cd转运相关基因表达情况,测定土壤中有效性Cd、Fe、Mn含量和根膜Cd、Fe和Mn含量。相同处理继续培养至水稻完熟期,收获植株和稻米并测定Cd含量和产量。【结果】在Cd污染土壤条件下,与正常灌溉处理相比,持续淹水显著降低了分蘖盛期水稻FP36和ZJZ17的Cd含量,根部降幅分别为39.5%和33.9%,地上部降幅分别为62.1%和71.7%。在完熟期也表现相同作用效果,持续淹水显著降低完熟期水稻FP36和ZJZ17根部、地上部和稻米中Cd含量,FP36根部、地上部和稻米分别降低36.4%、43.7%和36.8%,ZJZ17分别降低62.5%、61.5%和55.4%。研究发现,持续淹水显著降低了两个水稻品种的土壤有效性Cd含量(降幅分别为12.1%和17.7%)和根膜中Cd的含量(降幅分别为52.2%和43.1%)。Cd胁迫下,持续淹水增加了土壤有效性Fe(增幅分别为23.7%和10.3%)和有效性Mn含量(增幅分别为24.5%和43.9%),也使根膜中Fe(增幅分别为83.1%和81.5%)和Mn含量(增幅分别为41.5%和27.7%)显著增加。更为重要的是,持续淹水显著下调了两个水稻品种根部Os Nramp1(58.3%和58.0%)和Os LCD(21.6%和17.8%)基因的相对表达量。【结论】持续淹水通过降低土壤有效性Cd含量和抑制Cd吸收基因表达(Os Nramp1和Os LCD)的双重调控作用,降低了水稻对Cd的吸收和积累。
【Objective】 The objective of this study was to investigate the effect of continuous flooding on the Cd accumulation in different rice cultivars with different cadmium (Cd) contents. By analyzing the Cd, Cd contents and Cd uptake and transport of key genes in soils under continuous flooding conditions, Effect of flooding on Cd accumulation in rice and its regulation mechanism. 【Method】 Under the condition of pot experiment (exogenous adding 1.5 mg · kg-1 Cd Cl2) to rice tillering (FP36, Cd high accumulation variety) and Zhongjiazao 17 (ZJZ17 low Cd accumulation variety) At the beginning of the period, continuous flooding treatment and tillering stage sampling were used to analyze the content of Cd and Cd transport related genes, and the available Cd, Fe and Mn contents and the contents of Cd, Fe and Mn in the root membrane were determined. The same treatment was continued until rice maturity, plants and rice were harvested and the Cd content and yield were determined. 【Result】 Under Cd-contaminated soil conditions, continuous flooding significantly reduced the Cd content of rice FP36 and ZJZ17 at tillering stage, with the root declines of 39.5% and 33.9%, respectively, and the declines of aboveground areas were 62.1 % And 71.7%. The same effect was also observed at the maturing stage. Continuous flooding significantly reduced the Cd content in roots, shoots and rice at the end of maturing stage, and decreased 36.4%, 43.7% and 36.8% in roots, shoots and rice at the end of maturity, respectively A decrease of 62.5%, 61.5% and 55.4% respectively. The study found that continuous flooding significantly reduced soil available Cd content (12.1% and 17.7%, respectively) and Cd content in root membrane (52.2% and 43.1%, respectively) for both rice varieties. Under Cd stress, continuous flooding increased soil available Fe (23.7% and 10.3% increase) and Mn (24.5% and 43.9% increase, respectively), and also increased Fe (83.1% % And 81.5%) and Mn content (increased by 41.5% and 27.7% respectively). More importantly, continued flooding significantly down-regulated the relative expression of Os Nramp1 (58.3% and 58.0%) and Os LCD (21.6% and 17.8%) genes in the roots of two rice cultivars. 【Conclusion】 Continuous flooding reduced Cd uptake and accumulation in rice by reducing the soil available Cd content and inhibiting the expression of Cd uptake genes (Os Nramp1 and Os LCD).