Acclimation of the Photosynthetic Apparatus to Photosystem I or Photosystem II Light: Evidence from Quantum Yield Measurements and Fluorescence Spectroscopy of Cyanobacterial Cells
Acclimation of the Photosynthetic Apparatus to Photosystem I or Photosystem II Light: Evidence from Quantum Yield Measurements and Fluorescence Spectroscopy of Cyanobacterial Cells
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DOI：
10.1515/znc-1989-1-219
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发表时间：
1989-02
期刊：
影响因子：
--
通讯作者：
A. Melis;C. Mullineaux;J. Allen
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文献类型：
--
作者：
A. Melis;C. Mullineaux;J. Allen
蓝藻聚球藻6301细胞在光照下生长，其光谱组成有利于被光系统II(PS II)的藻胆体(PBS)捕光天线或光系统I(PS I)的捕光天线--叶绿素(CHI)吸收。在PS I光下生长的细胞具有较高的PS II/PS I和PBS/Chl比值。在PS II-光下生长的细胞产生相对较低的PS II/PS I和PBS/Chl比值。因此，两种驯化状态下的细胞之间的主要差异似乎是PBS-PS II和PS I复合体在类囊体膜中的相对浓度。对放氧量子效率的测量表明，当光系统化学计量比调整到特定的光条件时，细胞光合作用的效率更高。聚球藻6301在PBS激发下的放氧量子效率低于CHI激发下的放氧量子产率，这表明聚球藻PS II的光化学装置中的激发能量被猝灭。这一现象在PS II-Light中比在PS I-Light生长的细胞中更为明显。室温和77K荧光发射光谱表明，PbS中的过剩激发能没有转移到PS I中，这表明PbS-PS II复合体的激发能发生了非辐射和非光化学的衰减。这种非光化学猝灭是在PS II的激发超过其有效光化学能力的条件下发生的。
Abstract Cells of the cyanobacterium Synechococcus 6301 were grown under illumination whose spectral composition favoured absorption either by the phycobilisome (PBS) light-harvesting antenna of photosystem II (PS II) or by the chlorophyll (Chi) a light-harvesting antenna of photosystem I (PS I). Cells grown under PS I-light developed relatively high PS II/PS I and PBS/Chl ratios. Cells grown under PS II-light developed relatively low PS II/PS I and PBS/Chl ratios. Thus, the primary difference between cells in the two acclimation states appeared to be the relative concentration of PBS-PS II and PS I complexes in the thylakoid membrane. Measurements of the quantum yield of oxygen evolution suggested a higher efficiency of cellular photosynthesis upon the adjustment of photosystem stoichiometry to a specific light condition. The quantum yield of oxygen evolution was nevertheless lower under PBS than Chi excitation, suggesting quenching of excitation energy in the photochemical apparatus of PS II in Synechococcus 6301. This phenomenon was more pronounced in the PS II-light than in the PS I-light grown cells. Room temperature and 77 K fluorescence emission spectroscopy indicated that excess excitation energy in the PBS was not transferred to PS I, suggesting the operation of a non-radiative and non-photochemical decay of excitation energy at the PBS-PS II complex. This non-photochemical quenching was specific to conditions where excitation of PS II occurred in excess of its capacity for useful photochemistry.