IaPMEI17调控蕹菜品种间根细胞壁果胶吸附镉差异的分子机理

我国土壤镉污染严重，选育作物镉污染预防品种有利于保障农产品安全。申请人发现蕹菜根系果胶甲酯酶抑制因子IaPMEI17品种间表达差异显著，可能与品种间镉含量差异有关。由此假设，蕹菜IaPMEI17通过调控果胶甲酯酶（PME）活性影响果胶的去甲酯化，进而改变其镉吸附能力，控制镉吸收转运。本项目拟以蕹菜镉污染预防品种和高镉品种为对象，探明IaPMEI17调控品种间根细胞壁果胶镉吸附能力差异的分子机理。内容包括：（1）分析镉胁迫前后IaPMEI17表达量、果胶的甲酯化程度和镉含量，明确IaPMEI17与果胶镉吸附能力的关系；（2）利用酵母双杂交和GST pull-down技术，筛选和验证响应IaPMEI17的PME，阐明IaPME17调控果胶去甲酯化的分子机理；（3）采用模式植物拟南芥验证IaPMEI17及其调控的PME功能。本项目对于了解作物镉低积累的分子机理和选育镉污染预防品种有重要意义。

Cadmium (Cd) contamination in agricultural soils is a serious problem in China, so it is of great significance to select and breed Cd pullulation safe cultivars (Cd-PSCs). In our previous study, we found that the differential expression of pectin methylesterase inhibitor 17 (IaPMEI17) should be responsible for the cultivar-dependent shoot Cd accumulation in water spinach. Therefore, it was hypothesized that IaPMEI17 could regulate the demethylation of pectin by reducing the activity of pectin methylesterase (PME), and finally affects the Cd adsorption capacity of pectin. In the present study, we aimed to study the molecular mechanism of IaPMEI17 regulating Cd adsorption capacity of pectin in Ipomoea aquatica Forsk. using a Cd-PSC (QLQ) and a high Cd accumulation cultivar (T308). Firstly, the expression level of IaPMEI17, cell wall pectin content, and Cd concentration in pectin will be determined to investigate the relationship between IaPMEI17 and Cd concentrations in pectin. Secondly, the PME proteins that interacting with IaPMEI17 will be identified by yeast two hybrid assay and GST pull-down assay to explore the molecular mechanism of IaPMEI17 regulating pectin demethylation. Finally, the function of IaPMEI17 the PME that interacting with IaPMEI17 will be further verified by Arabidopsis thaliana overexpression and RNAi system. The results will be useful for understanding the molecular mechanism of low Cd accumulation in crops and the breeding of Cd-PSCs.