甘蔗花青素低温光保护生理分子机制及效应研究

The researches on the anthocyanins mainly focus on its extraction and purification process, physical and chemical properties, metabolism modulation and development and utilization in our country, and a few studies have concerned on its ecophysiological functions. Up to date, there have been very rare studies that have explored the photoprotective role of anthocyanin in plants in our country. Although the research on the ecophysiological characteristics of anthocyanins is hot outside of our country, most of them stay at the individual or the cell levels and very few studies have developed into cellular and molecular levels, and thus some hypotheses were growth and decline frequently. Based on our previous study on anthocyanins and the actual ecoenvironmental conditions in the main sugarcane growth region in Guangxi, from the point of scavenging of ROS and decreasing excitation pressure, several varieties with different chilling resistant bred by ourselves or introduced from abroad will be used, and the field and laboratory experiments will be carried out in this project. By means of chromatographic and mass spectrometry and molecular biological techniques, the project will study the antioxidant properties and the light use status of anthocyanins in sugarcane leaves under low temperature to explore its major phtoprotective mechanism from the physiological and molecular perspective. Besides, the project will study the influences of anthocyanins on the photosynthetic characteristics, the balance of pigments and resorption of nitrogen in sugarcane leaves under cold environment and will reveal the regulation mechanism of these properties. The implementation of this project will provide new idea for researches on sugarcane photoprotection and provide new data for the question why leaves are sometimes are red that disturbs us for a long time. In addition, the implementation of this project will promote the fundament changes of the hypothesis on the functions of anthocyanins to the level of theory.

国内花青素相关研究以提取纯化、理化性质、代谢调控和开发利用等居多，而生理生态相关研究较少，从光保护角度研究花青素生物学功能的报道就更少。国际上花青素光保护研究虽是热点，但多数研究都停留在个体或器官水平，很少有报道阐述其分子机制，于是出现各种假说此消彼长的复杂局面。项目立足于广西主要蔗区特定生态环境，在我们近年花青素相关研究的基础上，以清除活性氧和降低自由能这两种根本光保护机制为切入点，以自育及国外引进抗寒能力有显著差异的甘蔗品种为材料，设置大田及室内试验，借助现代质谱、色谱和分子生物学技术，研究花青素低温抗氧化状况及光能利用特性，揭示其光保护实现的关键生理分子机制；研究花青素合成对甘蔗光合特性、色素调配及N素再利用的影响，揭示其调节机制。项目实施为甘蔗低温光保护研究提供新思路，为回答至今困惑人们的"叶片为什么变红"问题提供新资料，同时为花青素生物学功能假说向生理生态理论层面过渡奠定基础。

国内花青素相关研究以提取纯化、理化性质、代谢调控和开发利用等居多，而生理生态相关研究较少，从光保护角度研究花青素生物学功能的报道就更少，国际上花青素光保护研究虽是热点，但很少有报道阐述其分子机制。项目立足于广西主要蔗区特定生态环境，以花青素合成能力有明显差别的桂糖28号、桂糖21号 (强抗寒品种)、新台糖16号、桂糖97-69 (中度抗寒材料)、新台糖22号、拔地拉 (弱抗寒品种)为主要材料，以所内资源圃600余份甘蔗种质为辅助材料，设置了野外大田试验、温室处理和培养箱栽培实验，借助传统生理生化技术、现代液-质联用测定技术、转录组测序及代谢组分析等手段，从甘蔗叶片花青素合成和抗氧化系统相互关系、对甘蔗叶片光能收支的影响、光合特性、色素调配及老叶矿质元素回收利用的影响等角度阐述了低温条件下甘蔗合成花青素的光保护生理分子机制。项目取得的核心发现为：1）起源于热带地区的外来冷敏感品种相对于本地选育的强抗寒品种，低温条件下其抗氧化系统和叶黄素循环两个关键光保护机制运行较弱，但它们可以合成相对高得多的花青素，有效增强低温光保护能力；2）单独低温和单独强光下花青素合成有限，低温强光（红光比白光更有效）结合则大幅增加，部分品种在低温解除后恢复过程中才大量合成花青素；稀薄紫色花青素显著提高甘蔗叶片光合效率，而红色浓郁花青素则降低光合效率，颜色的变化源于pH和浓度的差异，而不是种类的差别；3）花青素不但促进老叶N素再回收利用，对P、K、Mg等矿质元素同样有效。总之，逆境下花青素随次生代谢信号，在结构脆弱、生理代谢运行薄弱或受抑的部位产生，起临时多种保护作用，同时预警和加速养分回收利用。这些结果为甘蔗低温光保护研究提供了新思路，为花青素生物学功能假说向生理生态理论层面过渡奠定了基础，拓展了花青素生物学功能的内涵，同时为回答经典令人困惑的"叶片为什么变红"问题提供了新资料和新认识。