C3和C4作物膜脂对温室气体CO2浓度升高的响应

Elevated atmospheric CO2 (E[CO2]) is posing important influence on the development and physiological process of crops. Due to the different photosynthetic carbon assimilation process between C3 and C4 crops, there is a direct enhancement of photosynthesis in C3 crops under E[CO2], and the promotion in C4 crops is not obvious. However, the biochemical mechanism of this difference between the two crops is not clear. In the present project, we will treat rape and maize, two globally important crops with C3 and C4 photosynthetic pathway, with different concentrations of CO2. And use lipidomics method to profile 5 kinds of extraplastidic lipids, 3 kinds of plastidic lipids, 3 kinds of lysophospholipids and diacylglycerol of these two plants under various CO2 treatment. Through comparing the difference of lipidome between rape and maize, we will study the biochemical mechanism of different photosynthesis response of C3 and C4 crops to E[CO2]. Phosphatidic acid (PA) is an important signal molecule in the process of stomatal closure. Through detecting the changes of PA content, we want to know if PA work in E[CO2] induced stomatal closure. Through this study, We can understand the difference between of C3 and C4 lipidome profiles under various CO2 concentrations, and give some advices to the cropping practices and breeding of various crops.

温室气体CO2浓度增加（E[CO2]）对作物产生重要影响。C3、C4作物的光合碳同化过程不同，E[CO2]促进C3作物光合作用，对C4作物促进作用却不明显，然而具体的生化机制尚不清楚。由于脂类代谢与碳代谢、气孔及光合作用密切相关，项目拟以油菜和玉米作为C3、C4作物代表，利用脂类组学方法，解析其在不同CO2浓度下5种质体外（extraplastidic）脂类、3种叶绿体脂类、3种溶血磷脂以及甘油二脂的分子组成特点、相互联系及变化规律，检验对气孔开闭有重要作用的膜脂信号分子磷脂酸（PA）在E[CO2]下的含量变化及对气孔调控的影响。通过分析油菜和玉米膜脂组成样式异同和PA调控气孔作用的变化，探讨光合生理对E[CO2]响应差异背后的膜脂代谢的生化机制。该项目的研究对我们了解C3、C4作物膜脂组成样式及其对E[CO2]响应模式具有重要意义，也为全球气候变化背景下不同作物的合理种植及育种奠定基础。

预计到本世纪末温室气体CO2浓度将会增加到1000 ppm左右，CO2浓度增加必然会对农作物产生重要影响。我们选取了C3作物油菜，C4作物玉米和C3固氮作物大豆作为研究材料，在营养供应充足的条件下，研究它们对高浓度CO2（800 ppm）的响应。我们发现：（1）CO2浓度增加显著的促进了C3作物油菜的光合作用，然而对C4作物玉米的影响不大。油菜在高浓度CO2处理下可以维持高水平的胞间CO2浓度可能导致Rubisco酶更多的催化固定CO2的羧化反应，进而导致光合作用的增加；（2）CO2浓度增加对油菜和玉米膜脂组成产生的影响较小。然而，随着玉米的生长发育，显著的降低了玉米膜脂的双键指数，可能对玉米产生了氧化胁迫；（3）CO2增加可以促进大豆的光合作用，进而促进大豆的生长发育及果荚数量。CO2增加对大豆种子营养的影响比较复杂，种子中的抗氧化物质含量以及铁含量的降低，然而大豆种子中的亚油酸和钙元素增加。