不同玉米品种对Pb响应的根细胞壁多糖差异及机理

The lead (Pb) pollution in soils is a very serious problem in China, which cannot be removed completely in a short time. Therefore, it is an important and effective way to ensure food safety by screening and utilization of Pb tolerant and low accumulative crop varieties. In the present research, two maize varieties with different tolerance and accumulative abilities of soil Pb were selected as the studying material. (1) To understand the response of polysaccharide components and contents in root cell wall of the two maize varieties to Pb stress by a hydroponics experiment. (2) To explore the role of polysaccharide components in the Pb adsorption by root cell wall by the root cell wall modification and Pb adsorption experiments. (3) To find the key metabolic pathways for the root cell wall polysaccharides of the tolerant maize variety adapting to Pb stress by a metabonomics experiment on maize root cells using the gas chromatography-mass spectrometry (GC-MS). (4) To study the differential expression of the root cell proteins of the two maize varieties responding to Pb stress, identify its functions and analysis its role in cell wall polysaccharide metabolism and modification process by using the iTRAQ marker combined with LC-ESI-MS/MS proteomics technology. Finally to explain the physiological and molecular mechanisms of the polysaccharide in root cell wall of the two maize varieties responding to Pb stress. Results will provide a theory evidence for improving the Pb tolerant ability of maize by genetic modification and developing the Pb low accumulative maize varieties.

我国农田土壤Pb污染十分严重，短时间内又不能将其去除，因此，筛选和利用对Pb具有耐性且低累积作物品种，对于保障食品安全具有重要意义和应用价值。本项目拟以筛选到的对土壤Pb具有不同耐性和累积能力的2个玉米品种为供试材料，通过水培试验，研究2个玉米品种根细胞壁多糖的组成和含量对Pb胁迫的响应；通过对玉米根细胞壁改性及吸附试验，明确玉米根细胞壁多糖组分在Pb吸附过程中发挥的作用；用GC-MS技术对2个玉米品种根细胞进行代谢组学研究，寻找耐性玉米品种适应Pb胁迫的根细胞壁多糖关键代谢途径；用iTRAQ标记结合LC-ESI-MS/MS蛋白质组学技术，从蛋白质组学角度研究2个玉米品种根细胞蛋白对Pb响应的差异表达，鉴定其功能，分析其在细胞壁多糖代谢与修饰过程中的作用。揭示不同玉米品种根细胞壁多糖对Pb响应的生理和分子机制。为通过遗传改良玉米的Pb耐受能力，培育Pb低累积玉米品种提供理论依据。

我国农田土壤Pb污染十分严重，短时间内又不能将其去除，因此，筛选和利用对Pb具有耐性且低累积作物品种，对于保障食品安全具有重要意义和应用价值。本项目以所筛选到的对Pb具有不同耐性的2个玉米品种为研究材料，在不同Pb浓度处理下，开展盆栽和水培试验，运用植物生理学的理论和技术，分析了Pb胁迫下2个玉米品种根细胞壁多糖组分和含量变化及与Pb吸附量的关系、玉米根细胞壁对Pb的吸附动力学研究，揭示了不同玉米品种根细胞壁多糖组分对Pb胁迫响应差异的生理机制；用气相色谱-质谱联用(GC-MS)技术，对Pb胁迫下2个玉米品种根细胞进行代谢组学研究，探讨了不同玉米品种根细胞壁多糖代谢过程的差异，从细胞代谢水平分析了玉米根细胞壁多糖对Pb胁迫响应的生化机制；用iTRAQ标记结合LC-ESI-MS/MS这种先进的蛋白质组学研究技术，对Pb胁迫条件下2个玉米品种根细胞蛋白表达的变化进行分析，鉴定其蛋白功能，并分析相关蛋白在细胞壁多糖代谢过程中的作用，从蛋白质组学的角度解析不同玉米品种在Pb胁迫下根细胞壁多糖的响应差异，初步揭示了不同玉米品种根细胞壁多糖对Pb响应的分子机制。从而为通过遗传改良玉米的Pb耐受能力，培育Pb低累积玉米品种提供理论依据。

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