钾调控萝卜芽苗下胚轴中花青素积累的机理研究

To increase the anthocyanin content in fruits, vegetables and crops using safe and effective methods has been the focus of much recent attention due to numerous reports of its positive effects on human health. Potassium is one of the major mineral element that human body needs, and potassium shortage will result in myocardial injury, myasthenia, enteroplegia etc. Sprouts contain rich nutrition, but the potassium content in them is very low because of the traditional production technology. Our preliminary experiments showed that exogenous potassium addition could not only increase the content of potassium in radish sprouts, but also enhance the accumulation of anthocyanins in the hypocotyls. The related mechanisms is still unknown. This project will take advantage of radish sprouts as the materials and study: 1) the relationship between K+ distribution and anthocyanin biosynthesis; 2) the role of sugar metabolism in the K+-regulated anthocyanin biosynthesis with the treatments of inhibitors and analogues of sugar and inhibitors of potassium channels and transporters, and adopting the mutants of transporters hak5, akt and chx13; 3) the effects of K+ on the anthocyanin transport from endoplasmic reticulum to vacuole through analyzing the subcellular location of anthocyanins, the GST activity, the changes of vacuolar pH value and the activity of H+-PPase on tonoplast. The aim of the research is to disclose the mechanism of potassium in promoting anthocyanin accumulation，thus to improve the regulatory mechanism of anthocyanin biosynthesis. In addition, the results in this project will provide guidance for regulating the anthocyanin accumulation and increasing the nutrition of the vegetables in agricultural practice.

花青素对人体健康十分有益，提高水果、蔬菜及作物中花青素的含量是目前的研究热点。钾是人体必需的矿质元素，缺钾会引起心肌损伤，导致肌无力、肠麻痹等。芽苗类蔬菜营养丰富，但传统生产工艺导致其钾含量普遍偏低。我们前期研究发现，外源施钾不仅能提高萝卜芽苗中钾的含量，还能显著促进其下胚轴中花青素的积累，而相关机理尚不明确。本课题以萝卜芽苗为试验材料，重点研究内容为：1）探究内源K+浓度、分布与花青素合成和积累的关系；2）通过糖合成抑制剂、钾离子通道抑制剂等药理学试验与hak5、akt1和chx13等遗传学材料的结合研究，阐明糖代谢在K+调控的花青素合成中的作用；3）通过分析花青素转运蛋白GST活性、液泡中pH值、液泡膜H+-PPase活性等，揭示K+在花青素从内质网向液泡转运中的调控作用。预期研究结果将完善钾调控花青素积累的理论机制，为生产中通过施钾促进蔬菜花青素积累，提高营养品质提供科学依据。

钾是植物体内生长发育所必须的大量元素之一，通过调节酶活性、代谢物合成，信号转导、逆境胁迫以及渗透平衡等过程调控植物的生理生化过程。目前的研究表明钾素能够影响植物花青苷的积累，但是研究的结论不一致，并且并未有报道详细探究其中的分子机制。本文利用‘杨花萝卜’芽苗作为试验材料，通过探究钾对萝卜芽苗下胚轴花青苷和糖类物质含量的影响、对花青苷合成相关基因、糖代谢以及糖信号相关基因的表达水平的影响。取得的主要结论如下所示：.1、.KCl处理会抑制生长初期萝卜芽苗下胚轴花青苷的含量。.2、.糖代谢、激素信号转导途径参与钾对花青苷的调控。.3、.蔗糖能够作为底物和信号分子参与钾对萝卜芽苗下胚轴花青苷的调控。