沉水植物龙舌草无机碳利用策略的研究

我们前期的研究表明龙舌草是一种能够采用多种无机碳利用策略进行光合作用的特殊的沉水植物。本项目拟在前期工作基础上，研究不同CO2浓度下龙舌草昼、夜分别采用何种无机碳利用策略（C4途径、HCO3-利用、CAM途径）来应对水中低浓度CO2的胁迫；在此基础上，通过观测不同CO2浓度下龙舌草叶片解剖结构、光合作用关键酶活性与亚细胞定位、光合速率、δ13C值、昼夜有机酸代谢、叶片极化现象，阐明龙舌草不同无机碳利用策略的生理生化机制；同时，选择与C4途径、CAM途径、HCO3-利用紧密相关的光合作用关键酶基因，通过基因的时空表达分析与组织定位，阐明龙舌草不同无机碳利用策略的分子生物学机制。该研究将揭示不同CO2供应下龙舌草的无机碳利用策略，阐明龙舌草如何在简单的组织结构中实现CO2的浓缩和利用，为高等水生植物无机碳利用策略的研究提供参考。

Our previous studies showed that Ottelia alismoides is a very special submerged macrophyte which has various inorganic carbon acquisition strategies. In this project, we will measure which inorganic carbon acquisition strategies (C4、CAM and HCO3- utilization) play the leading role in O. alismoides during day and night at different CO2 concentrations; On the basis of above results, leaf microscopic and ultrastructural observation, key enzymes activity of photosynthesis measurement and subcellular localization, photosynthetic rate, δ13C, day and night organic acid metabolism measurement, pH change measurement of the leaf at both sides will make to illustrate physiological and biochemical mechanisms of inorganic carbon acquisition strategies in O. alismoides. Moreover, gene expression mode of key enzyme genes of photosynthesis which closely related to C4、CAM and HCO3- utilization and their localization will make at different time scale and different tissues to illustrate how these genes regulate C4、CAM and HCO3- utilization. From the above study, we want to illustrate how O. alismoides succeed in CO2 concentrating in such a simple structure and the transition mechanism of inorganic carbon acquisition strategies in submerged plant O. alismoides when in different CO2 concentrations and its adaptive significance. This study will provide theoretical basis for the study of inorganic carbon acquisition strategies in higher plants.