Ghildiyal M C, Sharma-Natu P
Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi 110012, India.
Indian J Exp Biol. 2000 Oct;38(10):961-6.
With rising level of CO2 in the atmosphere plants are expected to be exposed to higher concentration of CO2. Since, CO2 is a substrate limiting photosynthesis particularly in C3 plants in the present atmosphere, the impact of elevated CO2 would depend mainly on how photosynthesis acclimates or adjusts to the long term elevated level of CO2. Photosynthetic acclimation is a change in photosynthetic efficiency of leaves due to long term exposure to elevated CO2. This change in photosynthetic efficiency could be a biochemical adjustment that may improve the overall performance of a plant in a high CO2 environment or it could be due to metabolic compulsions as a result of physiological dysfunction. Acclimation has generally become synonymous with the word response, if long term exposure to elevated CO2 decreases the photosynthesis rate (Pn) at a given CO2 level, it is called negative acclimation, if it stimulates Pn at a given CO2 level, it is called positive acclimation. Photosynthetic acclimation is clearly revealed by comparing Pn of ambient and elevated CO2 grown plants at same level of CO2. Species level differences in acclimation to elevated CO2 have been reported. The physiological basis of differential photosynthetic acclimation to elevated CO2 is discussed in relation to the regulation of photosynthesis and photosynthetic carbon partitioning at cellular level.
随着大气中二氧化碳水平的上升，预计植物将暴露于更高浓度的二氧化碳环境中。由于在当前大气中，二氧化碳是限制光合作用的底物，尤其是在C3植物中，二氧化碳浓度升高的影响将主要取决于光合作用如何适应或调整到长期升高的二氧化碳水平。光合适应是指由于长期暴露于升高的二氧化碳环境中，叶片光合效率发生的变化。这种光合效率的变化可能是一种生化调节，它可能会提高植物在高二氧化碳环境中的整体性能，也可能是由于生理功能障碍导致的代谢强制作用。如果长期暴露于升高的二氧化碳环境中会在给定的二氧化碳水平下降低光合速率（Pn），那么适应通常就与“响应”这个词同义，这种情况被称为负适应；如果在给定的二氧化碳水平下刺激Pn，则被称为正适应。通过比较在相同二氧化碳水平下生长于环境二氧化碳浓度和升高二氧化碳浓度环境中的植物的Pn，可以清楚地揭示光合适应现象。已经报道了不同物种在适应升高的二氧化碳方面的差异。本文从细胞水平上光合作用的调节和光合碳分配的角度，探讨了对升高的二氧化碳进行不同光合适应的生理基础。
