Photosynthetic Acclimation, Carbohydrate Signaling and Molecular Control of Gene Expression in Response to Elevated Atmospheric Carbon Dioxide

西曼9808753自工业革命开始以来，地球大气中二氧化碳的浓度上升了约30%，这主要是化石燃料燃烧和土地利用变化的结果，保守地预计到21世纪末将翻一番。光合作用是生物圈中的主要生理过程，也是唯一能从大气中去除大量二氧化碳的生物过程，它本身对二氧化碳浓度非常敏感。在接触21世纪二氧化碳浓度后的短期内(几小时到几天)，光合作用的速率会大大增加，但从长期来看(几天到几周)，光合作用的“适应”可能会显著降低，这一过程的特征是光合作用装置的组成部分水平降低。这种驯化现象将对全球碳循环和生态系统的结构和功能产生重大影响，但其生物化学和分子基础尚不清楚。此外，植物物种在适应大气中二氧化碳浓度升高的光合作用能力方面可能有很大的不同。本研究项目的目的是：(1)了解植物感受二氧化碳浓度升高的生化途径(S)和光合作用基因表达的信号变化；(2)识别实际上改变基因表达并进而改变二氧化碳浓度升高时光合作用的分子机制；(3)确定物种在光合作用适应高浓度二氧化碳浓度时存在差异的生化和分子基础。

Seemann 9808753 Since the start of the industrial revolution, the concentration of C02 in the earth's atmosphere has risen by approximately 30%, primarily as a result of fossil fuel combustion and land-use changes, and is conservatively projected to double by the end of the 21st century. Photosynthesis, the major physiological process in the biosphere and the only biological process that removes a significant amount of C02 from the atmosphere, is itself extremely sensitive to C02 concentration. In the short term (hours to days) following exposure to 21st century C02 concentrations, the rate of photosynthesis is substantially increased, but in the long term (days to weeks) it may be significantly reduced as a result of an "acclimation" of photosynthesis, a process characterized by a reduction in the level of components of the photosynthetic apparatus. This acclimation phenomenon will have significant effects on both the global carbon cycle and ecosystem structure and function, but its biochemical and molecular basis are poorly understood. Furthermore, plant species may differ substantially in the extent that they may acclimate photosynthetic capacity to elevated atmospheric C02. The objectives of this research project are to: (1) understand the biochemical pathway(s) by which plants sense elevated C02 and signal changes in the expression of genes for photosynthesis; (2) identify the molecular mechanisms that in fact alter gene expression and consequently photosynthesis at elevated C02; and (3) determine the biochemical and molecular bases for species differences in photosynthetic acclimation to elevated C02,