Zivcak Marek, Kalaji Hazem M, Shao Hong-Bo, Olsovska Katarina, Brestic Marian
Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic.
Department of Plant Physiology, Faculty of Agriculture and Biology, Warsaw Agricultural University SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland.
J Photochem Photobiol B. 2014 Aug;137:107-15. doi: 10.1016/j.jphotobiol.2014.01.007. Epub 2014 Jan 21.
In conditions of long-lasting moderate drought stress, we have studied the photoprotective responses in leaves of wheat (Triticum aestivum L., cv. Katya) related to the photosynthetic electron and proton transport. The dark-interval relaxation kinetics of electrochromic bandshift (ECS) indicated a decrease of electric and an increase of osmotic component of the proton motive force in drought stressed leaves, but neither the total proton motive force (pmf) nor the thylakoid proton conductance (gH(+)) were affected. We observed the enhanced protection against overreduction of PSI acceptor side in leaves of drought stressed plants. This was obviously achieved by the rapid buildup of transthylakoid pH gradient at relatively low light intensities, directly associated to the steep increase of NPQ and the down-regulation of linear electron transport. It was further accompanied by the steep increase of redox poise at PSII acceptor side and PSI donor side. The early responses related to thylakoid lumen acidification in drought-stressed leaves could be associated with the activity of an enhanced fraction of PSI not involved in linear electron flow, which may have led to enhanced cyclic electron pathway even in relatively low light intensities, as well as to the drought-induced decrease of IP-amplitude in fast chlorophyll fluorescence kinetics.
在长期中度干旱胁迫条件下，我们研究了小麦（Triticum aestivum L.，品种Katya）叶片中与光合电子和质子运输相关的光保护反应。电致变色带移（ECS）的暗间隔弛豫动力学表明，干旱胁迫叶片中质子动力势的电场分量降低，渗透分量增加，但总质子动力势（pmf）和类囊体质子电导率（gH(+)）均未受影响。我们观察到干旱胁迫植株叶片中对PSI受体侧过度还原的保护增强。这显然是通过在相对较低光强下快速建立跨类囊体pH梯度实现的，这与NPQ的急剧增加和线性电子传递的下调直接相关。此外，PSII受体侧和PSI供体侧的氧化还原平衡也急剧增加。干旱胁迫叶片中与类囊体腔酸化相关的早期反应可能与不参与线性电子流的增强部分PSI的活性有关，这可能导致即使在相对较低光强下循环电子途径增强，以及干旱诱导的快速叶绿素荧光动力学中IP振幅降低。
