Characterization of the non-photochemical quenching of chlorophyll fluorescence that occurs during the active accumulation of inorganic carbon in the cyanobacterium Synechococcus PCC 7942
Characterization of the non-photochemical quenching of chlorophyll fluorescence that occurs during the active accumulation of inorganic carbon in the cyanobacterium Synechococcus PCC 7942
复制标题
蓝藻聚球藻 PCC 7942 中无机碳活跃积累期间发生的叶绿素荧光非光化学猝灭的表征
作者：
A. Miller;G. Espie;D. Bruce
以前的工作表明，聚球藻PCC7942的PS 2荧光产量最大的时候，细胞处于二氧化碳补偿点。无机碳(Ci)的加入，如CO_2或HCO_3-−，由于光化学(QP)和非光化学(QN)猝灭而导致荧光产率降低。在这篇文章中，我们描述了Ci加成对生长在高光强(500μ−光子数m−2 S−1)的细胞的量子化学效应的影响。在白光强度为250μ摩尔光子m−2 S−1的白光(WL)下，Ci诱导的QN比在低光下生长的细胞(50μm−2 S−1)大得多。在强光培养的细胞中，我们测得的QN值高达70%，而在弱光培养的细胞中，QN值约为16%。当细胞重新获得CO2补偿点时，当细胞被主要由PS 1吸收的补充远红光(FRL)照射时，或当细胞被增强的WL强度照射时，QN被缓解。这些特征表明，QN不是一种能量猝灭(QE)。补充FRL光照可显著促进光合作用放氧，这可能与qP和qN的变化有关。Ci加成引起的qp的增加表明，由于氧化的qA水平的增加，PS2的有效量子产率增加。Ci引起的QN的增加代表了PS2活性的降低，这与潜在量子效率的降低有关。77K荧光发射光谱没有诊断意义的变化与经典态跃迁有关，在经典态跃迁中，PS2的潜在量子产额的降低要么是由于吸收截面的减小，要么是由于激发能对PS1的‘溢出’增加。DCMU的加入迅速缓解了Ci诱导的QP(t0.5<；0.5 S)和qN(t0.5≃1.6 S)。这两个时间常数进一步支持了两种独立的猝灭机制。因此，我们在蓝藻中表征了一种新的形式的QN，与状态转换或能量猝灭无关，这是由在二氧化碳补偿点向细胞添加Ci而引起的。
Previous work has shown that the maximum fluorescence yield from PS 2 of Synechococcus PCC 7942 occurs when the cells are at the CO2 compensation point. The addition of inorganic carbon (Ci), as CO2 or HCO3−, causes a lowering of the fluorescence yield due to both photochemical (qp) and non-photochemical (qN) quenching. In this paper, we characterize the qN that is induced by Ci addition to cells grown at high light intensities (500 μmol photons m−2 s−1). The Ci-induced qN was considerably greater in these cells than in cells grown at low light intensities (50 μmol photons m−2 s−1), when assayed at a white light (WL) intensity of 250 μmol photons m−2 s−1. In high-light grown cells we measured qN values as high as 70%, while in low-light grown cells the qN was about 16%. The qN was relieved when cells regained the CO2 compensation point, when cells were illuminated by supplemental far-red light (FRL) absorbed mainly by PS 1, or when cells were illuminated with increased WL intensities. These characteristics indicate that the qN was not a form of energy quenching (qE). Supplemental FRL illumination caused significant enhancement of photosynthetic O2 evolution that could be correlated with the changes in qp and qN. The increases in qp induced by Ci addition represent increases in the effective quantum yield of PS 2 due to increased levels of oxidized QA. The increase in qN induced by Ci represents a decrease in PS 2 activity related to decreases in the potential quantum yield. The lack of diagnostic changes in the 77 K fluorescence emission spectrum argue against qN being related to classical state transitions, in which the decrease in potential quantum yield of PS 2 is due either to a decrease in absorption cross-section or by increased ‘spill-over’ of excitation energy to PS 1. Both the Ci-induced qp (t0.5<0.5 s) and qN (t0.5≃1.6 s) were rapidly relieved by the addition of DCMU. The two time constants give further support for two separate quenching mechanisms. We have thus characterized a novel form of qN in cyanobacteria, not related to state transitions or energy quenching, which is induced by the addition of Ci to cells at the CO2-compensation point.
DOI：
10.1016/s0005-2728(89)80166-5
发表时间：
1989-04-17
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
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作者：
BRUCE, D;BRIMBLE, S;BRYANT, DA
通讯作者：
BRYANT, DA