马铃薯在低温条件下的糖信号调控研究

In addition to their roles as metabolic resources and structural constituents of cells in plants, sugars have important hormone-like functions as primary messengers in signal transduction. They regulate various processes associated with plant growth and development. Accumulation of soluble carbohydrates is one of the best-known responses of plants to cold,but the reglulatory mechanism of sugar signal is unclear. In the planning proposal, potato is used as material, we will analyze the low temperature tolerance and the expression level of cold induced genes and proteins after treatment with different hexoses and disaccharids. The sourse and sensing pathway of sugar signal will be illustrated, especially the role of sugar derived from StvacINV1 will be demonstrated. The sugar signal transduction and regulation proteins and phytohormones will be understanded by treatment with different inhibitors. The functions of regulation factors which greatly effect the sugar signaling will be elucidated by RNA interference technology, and then the role of sugar signaling under low temperature in potato will be clarified. The data will help to understand the mechanism of sugar signaling in the cold acclimation，which will play a significant role in breeding cold-induced sweetening resistance potato variety.

植物体中的糖不仅作为能量来源和结构物质，在信号传导中也具有类似激素的初级信使作用，调控其生长和发育。低温诱导糖的积累是一个普遍的现象，但糖在低温条件下的信号调控机理仍不清楚。本研究以淀粉植物马铃薯为材料，研究各种外源己糖和双糖处理对其低温耐受性的影响及其作用的靶分子，分析低温条件下糖信号的来源和感应途径，重点分析StvacINV1基因介导的糖信号的调节作用；通过各种抑制剂处理，阐明糖信号调节靶分子的方式，筛选出参与信号转导和调节的蛋白质元件和激素分子，并采用RNA干扰技术沉默关键调节因子的基因表达，揭示其调节功能、与其它调节因子的关系和信号转导通路，探讨糖信号在马铃薯低温条件下的调控作用。该研究有助于阐明糖信号在植物低温耐受中的作用机制，并对马铃薯耐低温糖化品种的培育策略提供指导。

植物体中的糖不仅作为能量来源和结构物质，还可以直接作为抗氧化剂淬灭氧化物质，此外，糖在信号传导中也具有类似激素的初级信使作用，调节相关基因的表达和酶活性，从而调控植物的生长发育和逆境响应。本项目主要研究了外源糖和液泡酸性转化酶对马铃薯低温耐受性的调控作用。结果表明，相对于葡萄糖、果糖，外源蔗糖处理明显提高了马铃薯离体叶片和幼苗的低温耐受性，其调控机理是蔗糖处理增强了马铃薯低温胁迫下抗氧化物酶活性和脯氨酸的含量，减少了活性氧的积累，从而降低了丙二醛的含量和细胞膜的损伤，使马铃薯低温耐受性提高。用RNA干扰技术获得的液泡酸性转化酶基因（vacINV1）下调表达的转基因马铃薯（vacINV1-RNAi），其低温耐受性明显低于非转基因植株，其调控机制是vacINV1调节了低温胁迫下蔗糖代谢的相关酶活性和代谢产物的含量，而影响了低温诱导的脯氨酸的积累，导致细胞膜受损严重，从而降低了马铃薯的低温耐受性。此外，我们构建了马铃薯蔗糖转运蛋白2基因（StSUT2）的RNA干扰载体，并获得了马铃薯转基因株系（StSUT2-RNAi），其组培苗生长状态与非转基因植株无明显差异，但试管薯的诱导率和产量明显低于非转基因植株；将组培苗移栽至蛭石中生长后，StSUT2-RNAi株系比非转基因植株生长迟缓，其低温耐受性也明显低于非转基因植株。该研究结果对蔗糖用于提高植物耐寒性调节和马铃薯耐低温品种的培育提供了重要的理论依据。