Laboratory of Biophysics, Wageningen University and Research, Wageningen, the Netherlands.
Institute of Chemical Physics, Faculty of Physics, Vilnius University, Vilnius, Lithuania.
Nat Plants. 2018 Apr;4(4):225-231. doi: 10.1038/s41477-018-0127-8. Epub 2018 Apr 2.
Photosystem II of higher plants is protected against light damage by thermal dissipation of excess excitation energy, a process that can be monitored through non-photochemical quenching of chlorophyll fluorescence. When the light intensity is lowered, non-photochemical quenching largely disappears on a time scale ranging from tens of seconds to many minutes. With the use of picosecond fluorescence spectroscopy, we demonstrate that one of the underlying mechanisms is only functional when the reaction centre of photosystem II is closed, that is when electron transfer is blocked and the risk of photodamage is high. This is accompanied by the appearance of a long-wavelength fluorescence band. As soon as the reaction centre reopens, this quenching, together with the long-wavelength fluorescence, disappears instantaneously. This allows plants to maintain a high level of photosynthetic efficiency even in dangerous high-light conditions.
高等植物的光系统 II 受到热耗散的保护，可以防止光损伤，这种过程可以通过叶绿素荧光的非光化学猝灭来监测。当光强度降低时，非光化学猝灭在几十秒到几分钟的时间范围内基本消失。我们使用皮秒荧光光谱法证明，其中一种潜在机制只有在光系统 II 的反应中心关闭时才起作用，即当电子转移被阻断且光损伤风险较高时。这伴随着长波长荧光带的出现。一旦反应中心重新打开，这种猝灭以及长波长荧光就会立即消失。这使得植物即使在危险的高光条件下也能维持高的光合作用效率。
