Strategies providing success in a variable habitat: III. Dynamic control of photosynthesis in Cladophora glomerata

Abstract

Diurnal patterns of photosynthesis were studied in July and April populations of Cladophora glomerata (L.) Kutz. from open and from shaded sites. Summer samples exposed to full sunlight showed decreased efficiency of open photosystem II at noon, and only slight differences were found between samples that had grown at open or at shaded sites. Electron transport rate was limited at highest fluence rates in shade plants, and non-photochemical quenching (NPQ) revealed faster regulation in samples from open sites. Daily course of de-epoxidation was not linearly correlated with the course of NPQ. The comparison of samples from open and from shaded sites revealed a higher capacity of thermal energy dissipation and an increase in the total amount of xanthophyll-cycle pigments (21%) in samples from open sites. In April, down-regulation of the efficiency of open photosystem II was related to lower water temperature, and hence, increased excitation pressure. In April the pool size of xanthophyll-cycle pigments was increased by 21% in comparison with summer and suggested higher levels of thermal energy dissipation via de-epoxidized xanthophylls. In both, summer and spring the amount of xanthophyll-cycle pigments was 20% higher in samples from open sites. Acclimation of C. glomerata to growth light conditions was further shown by experimental induction of NPQ, indicating NPQ increases of 23%, and increases of 77% in the reversible component of NPQ in open site samples. The effect of temperature on photosynthetic rate was non-linear, and different optimum temperatures of electron transport rate and oxygen evolution were exhibited. [References: 31

Photosynthetic characteristics of a tropical population of Nitella cernua (Characeae, Chlorophyta)

“…Increases in temperature have been shown to generally induce higher ETR values in some species, due to increased enzymatic activity, whereas O 2 evolution generally increases at lower temperatures and decreases at when higher temperatures (Ensminger et al, 2001;Necchi, 2004a). Our results are consistent with this pattern, with higher performances of net photosynthesis during winter and increasing trend of ETR towards higher temperatures in summer.…”

“…The increments of enzymatic activity are compensated by increased respiration and other mechanisms, e.g. increases in pseudocyclic electron transport (Mehler reaction) and enhanced photorespiration, leading to decreases in net photosynthesis (Davison, 1991;Ensminger et al, 2001). In addition, atypical values under extreme combinations of irradiance and temperature (e.g.…”

“…In addition, atypical values under extreme combinations of irradiance and temperature (e.g. high temperature and irradiance for N. cernua) are also responsible for the nonlinear relationships of O 2 evolution and ETR in freshwater macroalgae (Ensminger et al, 2001;Necchi, 2004a).…”

pTAC2, -6, and -12 Are Components of the Transcriptionally Active Plastid Chromosome That Are Required for Plastid Gene Expression

“…Chlorophyll and carotenoid pigments were determined by HPLC according to Bü ch et al (1994). Samples were ground in liquid nitrogen in Eppendorf tubes and extracted as described by Ensminger et al (2001).…”

Photoacclimation in a tropical population of Cladophora glomerata (L.) Kützing 1843 (Chlorophyta) from southeastern Brazil

“…Light saturation parameter (I k ) and maximum photosynthetic rate (P max ) increased, whereas photosynthetic efficiency (±) became significantly lower with higher irradiances. Ensminger et al (2001) studied the plasticity of photosynthesis in the green alga Cladophora glomerata from open and shaded sites by measurements of chlorophyll fluorescence, pigment composition and oxygen evolution. A higher capacity of thermal energy dissipation (as indicated by non-photochemical quenching, NPQ, parameter) and an increase in the total amount of xanthophyll-cycle pigments were found in plants from open sites.…”