Melkonian Jeffrey, Owens Thomas G, Wolfe David W
Department of Crop and Soil Sciences, Cornell University, 1123 Bradfield Hall, Ithaca, NY, 14853-1901, USA,
Photosynth Res. 2004;79(1):71-82. doi: 10.1023/B:PRES.0000011921.64567.b2.
The effects of elevated (700 micromol mol(-1)) and ambient (350 micromol mol(-1)) CO(2) on gas exchange parameters and chlorophyll fluorescence were measured on bean (Phaseolus vulgaris) during 24 h chilling treatments at 6.5 degrees C. Consistent with previous research on this cultivar, photosynthetic decline during chilling was not significantly affected by CO(2) while post-chilling recovery was more rapid at elevated compared to ambient CO(2). Our primary focus was whether there were also CO(2)-mediated differences in demand on nonphotochemical quenching (NPQ) processes during the chilling treatments. We found that photosystem II quantum yield and total NPQ were similar between the CO(2) treatments during chilling. In both CO(2) treatments, chilling caused a shift from total NPQ largely composed of q(E), the protective, rapidly responding component of NPQ, to total NPQ dominated by the more slowly relaxing q(I), related to both protective and damage processes. The switch from q(E) to q(I) during chilling was more pronounced in the elevated CO(2) plants. Using complementary plots of the quantum yields of photochemistry and NPQ we demonstrate that, despite CO(2) effects on the partitioning of NPQ into q(E) and q(I) during chilling, total NPQ was regulated at both CO(2) levels to maximize photochemical utilization of absorbed light energy and dissipate only that fraction of light energy that was in excess of the capacity of photosynthesis. Photodamage did occur during chilling but was repaired within 3 h recovery from chilling in both CO(2) treatments.
在6.5摄氏度的24小时冷处理期间，测量了高浓度（700微摩尔每摩尔负一次方）和环境浓度（350微摩尔每摩尔负一次方）二氧化碳对菜豆（菜豆属）气体交换参数和叶绿素荧光的影响。与之前对该品种的研究一致，冷处理期间光合作用的下降不受二氧化碳显著影响，而与环境浓度二氧化碳相比，高浓度二氧化碳处理下冷处理后的恢复更快。我们主要关注的是在冷处理期间，非光化学猝灭（NPQ）过程的需求是否也存在二氧化碳介导的差异。我们发现，冷处理期间，两种二氧化碳处理下的光系统II量子产率和总NPQ相似。在两种二氧化碳处理中，冷处理导致总NPQ从主要由NPQ的保护性、快速响应成分q(E)组成，转变为由与保护和损伤过程相关的、弛豫较慢的q(I)主导的总NPQ。在高浓度二氧化碳处理的植株中，冷处理期间从q(E)到q(I)的转变更为明显。通过光化学和NPQ量子产率的互补图，我们证明，尽管在冷处理期间二氧化碳对NPQ在q(E)和q(I)之间的分配有影响，但在两种二氧化碳浓度下，总NPQ都受到调节，以最大限度地提高吸收光能的光化学利用率，只耗散超过光合作用能力的那部分光能。冷处理期间确实发生了光损伤，但在两种二氧化碳处理中，冷处理3小时后的恢复过程中光损伤都得到了修复。
