稻米品质形成对高CO2浓度和高温的应答及其生理机制

持续升高的大气CO2浓度和温度是全球气候变化的两个重要特征。气室研究表明，CO2浓度升高使稻米品质总体变劣，但这种趋势是否因生长温度而异？内在机理如何？目前尚不明确。最新出现的大型T-FACE系统在完全开放的大田条件下运行，为探明大气环境变化对稻米品质的实际影响及其机制提供了契机。本项目采用T-FACE技术同时增高水稻冠层CO2浓度和温度，研究高CO2浓度、温度及二者互作对不同水稻品种稻米品质的影响；同时以灌浆过程为主线，动态监测稻米淀粉（包括淀粉粒形态、结构及淀粉链长分布等）及蛋白含量（蛋白组分及氨基酸）的变化；解析这些响应与籽粒碳代谢关键限速酶活性及主要激素浓度变化的关系；并综合灌浆期淀粉和蛋白性状、酶活性及主要激素浓度的响应等方面揭示稻米品质形成过程对大气CO2浓度或/和温度升高的应答机制。本研究将利于增强对未来大气变化情景下水稻响应的预测能力，进而更有效制订应对气候变化的适应策略。

The increases in atmospheric carbon dioxide (CO2) concentrations and air temperature are the two most important attributes of global climate change. Previous chamber studies indicated an overall deterioration in grain quality by elevated CO2 concentration, but its physiological mechanism as well as whether such changes in grain quality would be altered by growth temperature were unclear. The recently developed T-FACE (Temperature-Free Air CO2 Enrichment) system provides us an opportunity to study the effects of atmospheric environment changes on rice quality and its mechanism under the completely open field condition. We will use T-FACE technology to increase the CO2 concentration and temperature of rice canopy simultaneously. Different cultivars will be used to study CO2 concentration, temperature and their interaction on grain quality formation of rice. In addition, the temporal variation in fine structures of rice starch (including starch grain morphology, structure and starch chain length distribution) and protein (protein components and amino acids) will be examined. In particular, the physiological mechanism responsible for rice quality changes under elevated CO2 concentration and temperature will be studied through investigating the key enzyme activity and main hormone concentration during grain filling stage. The relationship between these responses of starch and protein, enzyme activity, hormone concentration and grain quality will be analyzed to reveal the mechanism of rice quality formation in response to the elevated atmospheric CO2 concentration, temperature and the both. This prospective study will enhance our ability to predict the response of rice to atmospheric changes, and to develop a more effective adaptation strategy to cope with climate change.