We investigated acclimatory responses of Arabidopsis plants to drought and salinity conditions before the appearance of obvious signs of damage caused by these factors. We detected changes indicating an increase in the reduction level of the chloroplast plastoquinone pool (PQ pool) 5–7 days after introduction of the stress factors. After 10–14 days, a decrease in the size of PSII light harvesting antenna was observed in plants under conditions of drought and salinity. This was confirmed by a decrease in content of PSII antenna proteins and by downregulation of gene expression levels of these proteins under the stress conditions. No changes in values of performance index and maximum quantum yield of PSII were detected. Under drought and salinity, the content of hydrogen peroxide in leaves was higher than in control leaves. Thus, we propose that reduction of the size of PSII antenna represents one of the universal mechanisms of acclimation of higher plants to stress factors and the downsizing already begins to manifest under mild stress conditions. Both the PQ pool reduction state and the hydrogen peroxide content are important factors needed for the observed rearrangement.

中文翻译：

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光系统 II 光捕获天线尺寸的调节代表了高等植物适应胁迫条件的普遍机制

我们研究了拟南芥植物在这些因素造成的明显损害迹象出现之前对干旱和盐度条件的适应反应。我们检测到变化表明叶绿体质体醌池（PQ 池）在引入压力因素后 5-7 天的还原水平有所增加。10-14 天后，在干旱和盐分条件下，植物中观察到 PSII 光捕获天线的尺寸减小。这通过 PSII 天线蛋白含量的降低和这些蛋白在应激条件下基因表达水平的下调得到证实。没有检测到PSII的性能指数和最大量子产率值的变化。在干旱和盐分条件下，叶片中过氧化氢含量高于对照叶片。因此，我们提出减小 PSII 天线的尺寸是高等植物适应胁迫因素的普遍机制之一，并且在温和的胁迫条件下已经开始表现出尺寸缩​​小。PQ 池还原状态和过氧化氢含量都是观察到的重排所需的重要因素。