Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Cells. 2021 Sep 6;10(9):2329. doi: 10.3390/cells10092329.
In view of the current and expected future rise in atmospheric CO concentrations, we examined the effect of elevated CO on photoinhibition of photosystem I (PSI) under fluctuating light in . At 400 ppm CO, PSI showed a transient over-reduction within the first 30 s after transition from dark to actinic light. Under the same CO conditions, PSI was highly reduced after a transition from low to high light for 20 s. However, such PSI over-reduction greatly decreased when measured in 800 ppm CO, indicating that elevated atmospheric CO facilitates the rapid oxidation of PSI under fluctuating light. Furthermore, after fluctuating light treatment, residual PSI activity was significantly higher in 800 ppm CO than in 400 ppm CO, suggesting that elevated atmospheric CO mitigates PSI photoinhibition under fluctuating light. We further demonstrate that elevated CO does not affect PSI activity under fluctuating light via changes in non-photochemical quenching or cyclic electron transport, but rather from a rapid electron sink driven by CO fixation. Therefore, elevated CO mitigates PSI photoinhibition under fluctuating light at the acceptor rather than the donor side. Taken together, these observations indicate that elevated atmospheric CO can have large effects on thylakoid reactions under fluctuating light.
鉴于目前和预期未来大气 CO 浓度的上升，我们研究了在波动光下升高 CO 对光系统 I (PSI) 光抑制的影响。在 400 ppm CO 下，PSI 在从黑暗到光激活光的最初 30 秒内表现出瞬态过度还原。在相同的 CO 条件下，PSI 在从低光到高光转变 20 秒后高度还原。然而，当在 800 ppm CO 中测量时，这种 PSI 过度还原大大减少，表明升高的大气 CO 促进了波动光下 PSI 的快速氧化。此外，在波动光处理后，800 ppm CO 中的 PSI 残留活性明显高于 400 ppm CO，表明升高的大气 CO 减轻了波动光下 PSI 的光抑制。我们进一步证明，升高的 CO 不会通过非光化学猝灭或环式电子传递的变化来影响波动光下的 PSI 活性，而是来自 CO 固定驱动的快速电子汇。因此，升高的 CO 在受体而不是供体侧减轻了波动光下 PSI 的光抑制。总之，这些观察结果表明，升高的大气 CO 可以对波动光下类囊体反应产生重大影响。
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