Plants can quickly and dynamically respond to spectral and intensity variations of the incident light. These responses include activation of developmental processes, morphological changes, and photosynthetic acclimation that ensure optimal energy conversion and minimal photoinhibition. Plant adaptation and acclimation to environmental changes have been extensively studied, but many details surrounding these processes remain elusive. The photosystem II (PSII)-associated protein PSB33 plays a fundamental role in sustaining PSII as well as in the regulation of the light antenna in fluctuating light. We investigated how PSB33 knock-out Arabidopsis plants perform under different light qualities. psb33 plants displayed a reduction of 88% of total fresh weight compared to wild type plants when cultivated at the boundary of UV-A and blue light. The sensitivity towards UV-A light was associated with a lower abundance of PSII proteins, which reduces psb33 plants’ capacity for photosynthesis. The UV-A phenotype was found to be linked to altered phytohormone status and changed thylakoid ultrastructure. Our results collectively show that PSB33 is involved in a UV-A light-mediated mechanism to maintain a functional PSII pool in the chloroplast.

中文翻译：

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PSB33蛋白在UVA光照下维持植物叶绿体中的Photosystem II。

植物可以快速，动态地响应入射光的光谱和强度变化。这些反应包括激活发育过程，形态变化和光合适应，以确保最佳的能量转化和最小的光抑制作用。植物对环境变化的适应性和适应性已被广泛研究，但是围绕这些过程的许多细节仍然难以捉摸。与光系统​​II（PSII）相关的蛋白质PSB33在维持PSII以及在波动的光中调节光天线方面起着基本作用。我们研究了PSB33敲除拟南芥植物在不同光质下的表现。psb33在UV-A和蓝光的边界下种植时，与野生型植物相比，植物的总鲜重减少了88％。对UV-A光的敏感性与较低的PSII蛋白含量有关，这降低了psb33植物的光合作用能力。发现UV-A表型与改变的植物激素状态和类囊体超微结构有关。我们的结果共同表明PSB33参与了UV-A光介导的机制，以维持叶绿体中的功能性PSII库。