金属型植物生物量分配对重金属胁迫的响应及其调控机制研究

To reveal the ecological differentiation of plant under long-term contaminated conditions, comparative study between tolerant population and non-tolerant population of metallophyte is the hotspot and front in pollution ecology. Preliminary study confirmed that there were differences in biomass allocation between tolerant population and non-tolerant population under heavy metal stress, and there were significantly correlations between biomass allocation and acid invertase activities. To further understand the reasons why there were differences in acid invertase activities between tolerant population and non-tolerant population under heavy metal stress, we plan to comparatively study biomass allocation, acid invertase activities, content and subcellular localization of copper, active oxygen content, antioxidant enzymes activities, gene structure of acid invertase, and transcript level of acid invertase genes in tolerant population and non-tolerant population of Rumes dentatus L. and Rumex japonicus under copper stress by UV-VIS spectrum analysis, high performance liquid chromatographic analysis, atomic absorption spectrometric analysis, RT-PCR, 3' and 5'RACE, DNA sequencing, real-time quantitative PCR, and southern hybridization. The results will not only have important theory value in understanding the effect of biomass allocation on the adaptation of plant to polluted environment, but also have important realistic significance in phytoremediation by genetic modification of metallophyte.

通过对金属型植物的抗性与非抗性种群进行对比研究，探讨长期污染条件下植物的生态分化及其机理是污染生态学研究的前沿热点问题。前期研究证实重金属胁迫下金属型植物的抗性种群与非抗性种群在生物量分配方式上存在差异，并且生物量分配方式与酸性转化酶活性具有显著相关性。为进一步揭示重金属胁迫下种群间酸性转化酶活性差异产生的原因，本项目以金属型植物齿果酸模和羊蹄为试验材料，采用可见-紫外光谱分析、高效液相色谱分析、原子吸收光谱分析、RT-PCR、3'和5'RACE、DNA测序、实时荧光定量PCR、Southern杂交等技术，对铜胁迫下两个种群的生物量分配方式、酸性转化酶活性、铜亚细胞分布、活性氧含量、抗氧化酶活性、酸性转化酶基因结构以及酸性转化酶基因转录水平进行对比研究。研究结果对揭示生物量分配在植物抗污染进化中的作用具有重要的理论意义，对遗传改良金属型植物用于重金属污染土壤的植物修复也有潜在应用价值。

前期研究证实重金属胁迫下金属型植物的抗性种群与非抗性种群在生物量分配方式上存在差异，并且生物量分配方式与根中酸性转化酶活性具有显著相关性。为进一步揭示重金属胁迫下种群间酸性转化酶活性差异产生的原因，本项目以抗性与非抗性种群金属型植物根器官为研究对象，对重金属胁迫下两个种群的生物量分配方式、酸性转化酶活性、重金属亚细胞分布、活性氧含量、抗氧化酶活性、酸性转化酶基因结构以及酸性转化酶基因转录表达量进行对比研究。结果发现：①抗性种群具有更强的活性氧清除能力可能使其酸性转化酶蛋白避免遭受高浓度活性氧损伤而活性较高；②抗性种群细胞壁和液泡重金属含量不低于非抗性种群，然而抗性种群酸性转化酶活性显著高于非抗性种群，这说明种群间酸性转化酶活性差异并不是重金属亚细胞分布差异造成的；③推测的蛋白构象显示抗性种群酸性转化酶蛋白与底物的亲和性高于非抗性种群，这说明种群间酸性转化酶活性差异可能部分来自于基因结构差异；④种群间酸性转化酶基因转录表达量的差异可能是产生酶活性差异的一个直接原因。此研究对阐明长期污染条件下生物的适应性进化具有理论价值，同时也是进行生态修复和环境重建的基础性工作。