Tóth Szilvia Z, Schansker Gert, Strasser Reto J
Laboratory of Bioenergetics, University of Geneva, Chemin des Embrouchis 10, CH-1254 Jussy, Switzerland.
Biochim Biophys Acta. 2005 Jun 30;1708(2):275-82. doi: 10.1016/j.bbabio.2005.03.012. Epub 2005 Apr 12.
The effects of DCMU (3-(3',4'-dichlorophenyl)-1,1-dimethylurea) on the fluorescence induction transient (OJIP) in higher plants were re-investigated. We found that the initial (F(0)) and maximum (F(M)) fluorescence levels of DCMU-treated leaves do not change relative to controls when the treatment is done in complete darkness and DCMU is allowed to diffuse slowly into the leaves either by submersion or by application via the stem. Simultaneous 820 nm transmission measurements (a measure of electron flow through Photosystem I) showed that in the DCMU-treated samples, the plastoquinone pool remained oxidized during the light pulses whereas in uninhibited leaves, the F(M) level coincided with a fully reduced electron transport chain. The identical F(M) values with and without DCMU indicate that in intact leaves, the F(M) value is independent of the redox state of the plastoquinone pool. We also show that (i) the generally observed F(0) increase is probably due to the presence of (even very weak) light during the DCMU treatment, (ii) vacuum infiltration of leaf discs leads to a drastic decrease of the fluorescence yield, and in DCMU-treated samples, the F(M) decreases to the I-level of their control (leaves vacuum infiltrated with 1% ethanol), (iii) and in thylakoid membranes, the addition of DCMU lowers the F(M) relative to that of a control sample.
重新研究了二氯苯基二甲基脲（DCMU，3-(3',4'-二氯苯基)-1,1-二甲基脲）对高等植物荧光诱导瞬变（OJIP）的影响。我们发现，当在完全黑暗中进行处理且通过浸没或经由茎部施加使DCMU缓慢扩散到叶片中时，经DCMU处理的叶片的初始（F(0)）和最大（F(M)）荧光水平相对于对照没有变化。同时进行的820 nm透射测量（衡量通过光系统I的电子流）表明，在经DCMU处理的样品中，在光脉冲期间质体醌库保持氧化状态，而在未受抑制的叶片中，F(M)水平与完全还原的电子传递链一致。有和没有DCMU时相同的F(M)值表明，在完整叶片中，F(M)值与质体醌库的氧化还原状态无关。我们还表明：（i）通常观察到的F(0)增加可能是由于DCMU处理期间存在（即使非常微弱的）光；（ii）叶圆片的真空渗透导致荧光产量急剧下降，并且在经DCMU处理的样品中，F(M)降低至其对照（用1%乙醇真空渗透的叶片）的I水平；（iii）在类囊体膜中，添加DCMU相对于对照样品降低了F(M)。
