Faculty of Science, University of Ostrava, 30. dubna 22, 701 03 Ostrava, Czech Republic.
Faculty of Science, University of Ostrava, 30. dubna 22, 701 03 Ostrava, Czech Republic; Global Change Research Institute, The Czech Academy of Sciences, Bělidla 986/4a, 603 00 Brno, Czech Republic.
J Photochem Photobiol B. 2019 Aug;197:111535. doi: 10.1016/j.jphotobiol.2019.111535. Epub 2019 Jun 19.
Measurement of Pulse-Amplitude-Modulated (PAM) chlorophyll a fluorescence is widely used method for obtaining information on the functional state of photosystem II (PSII). Recently, it has been shown that some of long-established fluorescence parameters must be interpreted with caution, when the light-induced chloroplast movements occur. In our work we have analyzed the effect of chloroplast movements on these parameters. We have derived new parameters that are independent of the change in PSII absorption occurring during measurement. To verify whether there is a need for new parameters or the difference between the parameters commonly used and the newly derived ones is insignificant, we conducted an experiment with Arabidopsis thaliana wild type plants and its phot1 phot2 mutant defective in chloroplast movement. Plants were exposed to light of different qualities (450, 470, 550 or 660 nm) and quantities (100, 400 or 1200 μmol m s) for up to 40 min. Since the blue light-induced chloroplast avoidance reaction is a photoprotective mechanism, we expected that phot1 phot2 mutant will compensate the lack of this mechanism by increasing non-photochemical quenching. However, using the light at both 450 and 470 nm, the calculation of commonly used parameter, Φ (quantum yield of regulated light-induced thermal energy dissipation in PSII) based on Hendrickson et al. [L. Hendrickson, R.T. Furbank, W.S. Chow, Photosynth. Res. 82 (2004) 73-81] showed the opposite. On the other hand, the results obtained using our newly proposed formulae to determine quantum yield of PSII thermal energy dissipation were in line with our assumption. Thus, the experimental data showed that some formulae of fluorescence parameters are dependent on the change in PSII absorption and need to be interpreted carefully. On the contrary, the formulae introduced by us can remove the effect of changes in PSII absorption that occur during measurement, without additional measurements, and give the real estimate of light-induced non-photochemical quenching.
脉冲幅度调制（PAM）叶绿素荧光测量是广泛用于获取光合作用系统 II（PSII）功能状态信息的方法。最近，已经表明，当发生叶绿体运动时，一些长期确立的荧光参数必须谨慎解释。在我们的工作中，我们分析了叶绿体运动对这些参数的影响。我们推导出了新的参数，这些参数与测量过程中 PSII 吸收的变化无关。为了验证是否需要新的参数，或者常用参数与新推导出的参数之间的差异是否不显著，我们对拟南芥野生型植物及其叶绿体运动缺陷的 phot1 phot2 突变体进行了实验。植物暴露在不同质量（450、470、550 或 660nm）和数量（100、400 或 1200µmol•m-2•s-1）的光下长达 40 分钟。由于蓝光诱导的叶绿体回避反应是一种光保护机制，我们预计 phot1 phot2 突变体将通过增加非光化学猝灭来补偿这种机制的缺乏。然而，使用 450 和 470nm 的光，根据 Hendrickson 等人的[L. Hendrickson, R.T. Furbank, W.S. Chow, Photosynth. Res. 82 (2004) 73-81]计算常用参数 Φ（PSII 中调节的光诱导热能耗散的量子产率）表明结果相反。另一方面，使用我们新提出的公式确定 PSII 热能耗散量子产率得到的结果与我们的假设一致。因此，实验数据表明，一些荧光参数的公式依赖于 PSII 吸收的变化，需要仔细解释。相反，我们引入的公式可以在不进行额外测量的情况下消除测量过程中 PSII 吸收的变化的影响，并给出光诱导非光化学猝灭的真实估计。
