It is well known that PsbS is a key protein for the proper management of excessive energy in plants. Plants without PsbS cannot trigger non-photochemical quenching, which is crucial for optimal photosynthesis under variable conditions. Our studies showed wild-type plants had enhanced tolerance to UV-C-induced cell death (CD) upon induction of light memory by a blue or red light. However, npq4-1 plants, which lack PsbS, as well as plants overexpressing this protein (oePsbS), responded differently. Untreated oePsbS appeared more tolerant to UV-C exposure, whereas npq4-1 was unable to adequately induce cross-tolerance to UV-C. Similarly, light memory induced by episodic blue or red light was differently deregulated in npq-4 and oePsbS, as indicated by transcriptomic analyses, measurements of the trans-thylakoid pH gradient, chlorophyll a fluorescence parameters, and measurements of foliar surface electrical potential. The mechanism of the foliar CD development seemed to be unaffected in the analysed plants and is associated with chloroplast breakdown. Our results suggest a novel, substantial role for PsbS as a regulator of chloroplast retrograde signalling for light memory, light acclimation, CD, and cross-tolerance to UV radiation.

中文翻译：

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Photosystem II 22kDa蛋白质水平-过量光诱导记忆，对UV-C的交叉耐受性和电信号调节的先决条件。

众所周知，PsbS是正确管理植物中过多能量的关键蛋白。没有PsbS的植物无法触发非光化学猝灭，这对于在可变条件下实现最佳光合作用至关重要。我们的研究表明，通过蓝光或红光诱导的光记忆，野生型植物对UV-C诱导的细胞死亡（CD）的耐受性增强。但是，缺少PsbS的npq4-1植物以及过表达该蛋白的植物（oePsbS）的反应不同。未经处理的oePsbS似乎更耐受UV-C暴露，而npq4-1无法充分诱导对UV-C的交叉耐受。同样，如转录组分析，跨类囊体pH梯度测量，叶绿素a的荧光参数，并测量叶表面的电势。叶面CD发育的机制似乎在分析的植物中不受影响，并且与叶绿体分解有关。我们的结果表明，PsbS作为叶绿体逆向信号调节剂的光记忆，光适应，CD和对UV辐射的交叉耐受性具有新颖，实质性作用。