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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >A zeaxanthin-independent nonphotochemical quenching mechanism localized in the photosystem II core complex
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A zeaxanthin-independent nonphotochemical quenching mechanism localized in the photosystem II core complex

机译：玉米黄素非依赖性非光化学猝灭机制位于光系统II核心配合物中。

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摘要

Illumination of dark-adapted barley plants with low light transiently induced a large nonphotochemical quenching of chlorophyll fluorescence. This reaction was identified as a form of high-energy-state quenching. Its appearance was not accompanied by zeaxanthin synthesis but was associated with a reversible inactivation of a fraction of photosystem II (PSII) centers. Both the fluorescence quenching and PSII inactivation relaxed in parallel with the activation of the Calvin cycle. We interpret the induction of this phenomenon as due to the generation of a quenched state in the PSII core complex. This reaction is probably caused by the transient overacidification of the thylakoid lumen, whereas its dissipation results from the relaxation of both the pH gradient across the thylakoid membrane and redox pressure upon activation of carbon fixation. At saturating light intensities, inactivation of PSII was still observed at the onset of illumination, although its recovery did not result in dissipation of high-energy quenching, which presents typical characteristics of an antenna-associated quenching at steady state. Reaction-center quenching seems therefore to be a common transient feature during illumination, being replaced by other phenomena (photochemical or antenna quenching and photoinhibition), depending on the balance between light and carbon fixation fluxes.
机译：暗适应的大麦植物在低光照下的照射会短暂诱导叶绿素荧光的大量非光化学猝灭。该反应被鉴定为高能态猝灭的形式。它的出现并不伴随着玉米黄质的合成，而是与部分光系统II（PSII）中心的可逆失活有关。荧光猝灭和PSII失活均与Calvin循环的激活平行。我们将这种现象的产生解释为归因于PSII核心复合物中淬灭态的产生。该反应可能是由于类囊体腔的短暂过度酸化引起的，而其耗散则是由于整个类囊体膜的pH梯度的松弛和碳固定激活后的氧化还原压力的减弱。在饱和光强度下，在照亮开始时仍观察到PSII失活，尽管其恢复并未导致高能猝灭的消散，这表现出稳定状态下天线相关猝灭的典型特征。因此，根据光和碳固定通量之间的平衡，反应中心猝灭似乎是照明过程中的常见瞬态特征，已被其他现象（光化学或天线猝灭和光抑制）取代。

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