Predicting Light Acclimation in Cyanobacteria from Nonphotochemical Quenching of Photosystem II Fluorescence, Which Reflects State Transitions in These Organisms

Abstract

An important factor in photosynthetic ecophysiology is the light regime that a photobiont is acclimated to exploit. In a wide range of cyanobacteria and cyano-lichens, the easily measured fluorescence parameters, coefficient of nonphotochemical quenching of photosystem II variable fluorescence (q,) and nonphotochemical quenching, decline to a minimum near the acclimated growth light intensity. This characteristic pattern predicts the integrated light regime to which populations are acclimated, information that is particularly useful for cyanobacteria or cyano-lichens from habitats with highly variable light intensities. q, reflects processes that compete with photosystem II photochemistry for absorbed excitation energy. In cyanobacteria, we find no evidence for energy-dependent quenching mechanisms, which are the predominant components of q, in higher plants. Instead, in cyanobacteria, q, correlates closely with the excitation flow from the phycobilisome to photosystem I, indicating that q, reflects the state transition mechanism for equilibration of excitation from the phycobilisome to the two photosystems.Chlorophyll fluorescence analysis is a useful monitor of photosynthesis, because it is noninvasive, sensitive, and scalable over large ranges of time, light, and distance. For natural samples, fluorescence signals are specific to photobionts and allow in situ measurements of small or dilute mixed natural populations. Chlorophyll fluorescence quenching analysis has been widely applied to characterize photosynthetic metabolism in cyanobacteria and cyanolichens (Lange et al., 1989;Miller et al

Phytoplankton diversity and photosynthetic acclimation along a longitudinal transect through a shallow estuary in summer

“…They can be assigned to the high percentage of cyanobacterial phytoplankton for several reasons, e.g. specificity of the photosynthetic state in darkness (Campbell & Öquist 1996), but also limits of PAM measurements for the discrimination of phycobiliprotein fluorescence emission and PSII emission. The latter seemed to be of minor importance for slight differences of the values during our investigations, since decreasing photosynthetic capacity with an increasing PC:PSII fluorescence emission ratio in the set of phytoplankton samples was not observed (data not shown).…”

“…In addition, significant drawbacks of PAM measurements predominantly can be assumed for cyanobacteria with artificially high phycobiliprotein content due to cultivation in the laboratory (Campbell et al 1998), but the dominance of the PBS antenna (Fig. 8) (Campbell & Öquist 1996) and/or that are subject to severe stress (nutrient deprivation, oxidative agents), affecting photosynthetic performance directly. Possibly, shadowing by terrestrial and aquatic higher plants, high nutrient concentrations, and the comparably high percentage of photosynthetic eukaryotes (Fig.…”

Effects of Iron on Growth, Pigment Content, Photosystem II Efficiency, and Siderophores Production of Microcystis aeruginosa and Microcystis wesenbergii

“…Chlorophyll fluorescence measurements were conducted using the PHYTO-PAM phytoplankton analyzer (Heinz Walz, Effeltrich, Germany). The maximum photochemical efficiency of PS II (maximal PS II quantum yield), maximal relative electron transport rates through PS II (ETR max ), and saturating light levels (I k ) of M. aeruginosa and M. wesenbergii were obtained in Light Curve-windows and Report-windows of PHYTO-PAM [1].…”

Photosynthetic field capacity of cyanobacteria of a tropical inselberg of the Guiana Highlands

“…In addition to chlorophyll in the photosystems, their phycobilisomes with the pigments phycocyanin and phycoerythrin, primarily attached to the photosystem II (PSII) dimers, extend the spectrum of visible light usable for photosynthesis. It is not clear, however, whether the phycobilisomes playa role in protection from surplus irradiance (Campbell & Oquist, 1996). Terrestrial cyanobacteria possess only a small amount of zeaxanthin (DemmigAdams, 1990;Demmig-Adams & Adams, 1992), which must be considered too low to affect heat dissipation significantly (Leisner ef al., 1994; Lakatos ef 01., 200 I).…”