The stoichiometry and antenna size of the two photosystems in marine green algae, Bryopsis maxima and Ulva pertusa, in relation to the light environment of their natural habitat

Abstract

The stoichiometry and antenna sizes of the two photosystems in two marine green algae, Bryopsis maxima and Ulva pertusa, were investigated to examine whether the photosynthetic apparatus of the algae can be related to the light environment of their natural habitat. Bryopsis maxima and Ulva pertusa had chlorophyll (Chl) a/b ratios of 1.5 and 1.8, respectively, indicating large levels of Chl b, which absorbs blue-green light, relative to Chl a. The level of photosystem (PS) II was equivalent to that of PS I in Bryopsis maxima but lower than that of PS I in Ulva pertusa. Analysis of Q(A) photoreduction and P-700 photo-oxidation with green light revealed that >50% of PS II centres are non-functional in electron transport. Thus, the ratio of the functional PS II to PS I is only 0.46 in Bryopsis maxima and 0.35 in Ulva pertusa. Light-response curves of electron transport also provided evidence that PS I had a larger light-harvesting capacity than did the functional PS II. Thus, there was a large imbalance in the light absorption between the two photosystems, with PS I showing a larger total light-harvesting capacity than PS II. Furthermore, as judged from the measurements of low temperature fluorescence spectra, the light energy absorbed by Chl b was efficiently transferred to PS I in both algae. Based on the above results, it is hypothesized that marine green algae require a higher ATP:NADPH ratio than do terrestrial plants to grow and survive under a coastal environment.

Photosynthesis in relation to D1, PsaA and Rubisco in marine and brackish water ecotypes of Fucus vesiculosus and Fucus radicans (Phaeophyceae)

“…This interpretation of the 77 K fluorescence emission of the brackish ecotype of F. vesiculosus in Gylle et al (2011) appears to be in line with the immunoblot signals of D1/PsaA (Table 1). The PSII/PSI ratio differ between different organisms and have been observed to be 1.43-1.72 in some terrestrial plants, 0.43 in blue-green algae and 0.84-1.03 in some green algae (Melis & Brown, 1980;Falkowski et al, 1981;Yamazaki et al, 2005;Fan et al, 2007).…”

Photoacclimation of the seagrass Halophila stipulacea to the dim irradiance at its 48‐meter depth limit

“…Also spectral changes can affect light absorption by altering the composition and ratio of the two photosystems (PSs) and, thus, photosynthetic rates and plant growth (Fujita 1997;Falkowski and Raven 2007). Among marine macrophytes, such spectral changes were shown to influence the functionality of the two PSs as found for the green macroalgae Ulva pertusa and Bryopsis maxima (Yamazaki et al 2005). Regarding seagrasses, only two studies have reported on changes in the PS composition: one in shallow-growing plants during various seasons (Major and Dunton 2000) and another along a narrow depth gradient down to 1.6 m (Major and Dunton 2002).…”

Comparative Extraction of Chlorophylls in Selected Forest and Savanna Mosses Using Dimethylsulphoxide and Acetone

“…It has been shown that shade tolerant species produce a higher proportion of chlorophyll b relative to chlorophyll a, which leads to a lower chlorophyll a/b ratio, to enhance the efficiency of blue light absorption in low light environments (Yamazaki et al, 2005). Forest mosses in the present study responded in the opposite direction.…”