Krieger-Liszkay Anja
Université Paris-Saclay, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Gif-sur-Yvette Cedex, France.
Physiol Plant. 2025 May-Jun;177(3):e70335. doi: 10.1111/ppl.70335.
Photosynthesis is driven by light absorbed by pigments situated in the antenna of the photosystems. Depending on the light quality, there is a difference in the absorption of Photosystems I and II. A balanced light absorption between both photosystems is required for optimal photosynthesis. State transitions are the acclimation response of the photosynthetic apparatus that allows adjusting the antenna size of the two photosystems. The dependency of chlorophyll fluorescence quenching parameters on the light quality was investigated in Arabidopsis wild type and state transition mutants. The parameter qL, indicating the fraction of open Photosystem II reaction centers, showed a large dependency on the quality of the actinic light in state transition mutants incapable of performing the transition to State 2. While the difference between wild type and these mutants was small in blue or red light, the difference was much more pronounced when cyan or green light was used instead. The phosphatase mutant pph, with the mobile part of the light harvesting Complex II locked at Photosystem I, the chlorophyll b-less mutant ch1, and phototropin mutants phot1 and phot2 affected in chloroplast movement did not show such low qL in cyan or green light. This shows that overexcitation of Photosystem II was responsible for the low qL in Arabidopsis state transition mutants stn7, nsi1, and nsi2.
光合作用由位于光系统天线中的色素吸收的光驱动。根据光质的不同，光系统I和光系统II的吸收存在差异。两个光系统之间的平衡光吸收是最佳光合作用所必需的。状态转换是光合装置的适应性反应，可调节两个光系统的天线大小。在拟南芥野生型和状态转换突变体中研究了叶绿素荧光猝灭参数对光质的依赖性。表示开放的光系统II反应中心比例的参数qL，在无法进行向状态2转换的状态转换突变体中，对光化光的质量表现出很大的依赖性。虽然野生型和这些突变体在蓝光或红光下差异很小，但当使用青光或绿光时，差异则更为明显。磷酸酶突变体pph，其光捕获复合体II的可移动部分锁定在光系统I上，叶绿素b缺失突变体ch1，以及在叶绿体运动中受影响的向光素突变体phot1和phot2，在青光或绿光下并未表现出如此低的qL。这表明光系统II的过度激发是拟南芥状态转换突变体stn7、nsi1和nsi2中qL较低的原因。
