硒调控茶树氟吸收转运的作用及其机理

Tea plants are hyper-accumulators of fluoride, excessive intake over the long term may have a negative impact on health. Application of selenite can reduce harmful elements accumulation in plant. We discover application of Se can reduce the tea plant contents of fluoride, but the mechanism of selenite reduce fluoride absorption and accumulation are still not well-understood. XRF will be used to investigate the distribution of se and F in different root zone, combination of radioactive techniques was used to study transport characteristics of the fluoride in the xylem and phloem. Patch clamp technology and RT-qPCR were used to research the mode of transmembrane transport of fluoride, analyse this processes being influenced by the selenite. NanoSIMS was used to determine the subcellular localization of Se and F and the three-dimensional shape of cell. 19FNMR and XPS will be used to investigate the molecular morphology of Se and F in the plant’s cells and sub-cells. To explain the relationship between accumulation and vacuolar compartmentalization. Through the above research, the effect of Se on the regulation mechanism of fluorine absorption was clarified. The results of this experiment will provide a theoretical basis for reduce fluorine content of tea.

茶树是富氟植物，长期饮用高氟茶会带来健康隐患。硒能够与多种有害元素产生拮抗效应，降低植物中的有害元素含量，申请者前期研究发现硒可以抑制茶树对氟的吸收，但硒对茶树氟吸收的调控作用尚未探明。鉴此，本项目以茶树为研究材料，采用XRF等技术原位分析研究硒、氟在茶树不同根区、根截面的时空分布特征，运用膜片钳和RT-qPCR技术研究氟的跨膜转运模式与相关转运蛋白基因的表达，分析硒对氟跨膜转运的影响，阐明硒对茶树根系氟吸收的作用机理；结合同位素示踪技术研究氟的木质部与韧皮部运输特征及其与硒的关系；采用NanoSIMS和XPS等技术分析氟、硒的亚细胞定位及单细胞三维构象，鉴定细胞内氟、硒的赋存形态，明确两者在细胞与亚细胞水平上的区隔位点与赋存形态差异及其与氟积累的关系。通过上述研究，以期深入剖析茶树中硒在氟的吸收转运过程中的调控作用机理，为降低茶叶中氟积累提供理论依据。

茶树是富氟植物，对茶树降氟技术的深入研究，为饮茶安全提供了新的依据。前期研究发现氟的积累及解毒与硒之间存在密切的交互作用，但其内在机制仍不清楚。本项目首先创建并完善了利用放射性同位素示踪技术研究氟在茶树体内动态运输的技术体系。水培实验发现，硒处理可以减少茶树叶片氟含量，促进氟在根系的滞留，减少茶树叶片中水溶性氟含量的比例。低浓度氟可以促进硒在茶树体内的积累。硒通过降低丙二醛的含量，提高抗氧化酶（SOD、POD和CAT）活性来改善氟诱导的氧化损伤。硒可以明显减少茶树叶片和根系中镁、铅的含量。叶片喷施实验表明，喷施硒可以明显降低茶树叶片和茎中的水溶性氟含量，但对根系氟含量无显著影响。无机硒在茶树体内可以转化为有机硒，茶树叶片中有机硒含量占总硒含量80%以上。外源硒处理可以显著降低茶树叶片中重金属元素铬、镉、铅和铜的含量，而对茶树生长所需的钾、钙、铁、锌元素无显著影响。硒可以提高叶片中儿茶素和咖啡碱的含量，增强叶片的光合能力。