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

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%，主要是由于化石燃料的燃烧和土地利用的变化，保守估计到21世纪末将翻一番。光合作用是生物圈中主要的生理过程，也是唯一从大气中去除大量二氧化碳的生物过程，而光合作用本身对二氧化碳浓度极为敏感。在暴露于21世纪二氧化碳浓度后的短期内（数小时到数天），光合作用的速率显著增加，但在长期内（数天到数周），由于光合作用的“适应”，光合作用的速率可能显著降低，这是一个以光合作用装置成分水平降低为特征的过程。这种驯化现象对全球碳循环和生态系统的结构和功能都有重要影响，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二氧化碳升高的光合能力方面可能存在很大差异。本研究项目的目标是：(1)了解植物感知二氧化碳升高和光合作用基因表达信号变化的生化途径；(2)在二氧化碳浓度升高的情况下，确定改变基因表达和光合作用的分子机制；(3)确定物种光合适应二氧化碳升高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,