Regulation of the Photosynthetic Adaptation in Scenedesmus Obliquus Depending on Blue and Red Light

Abstract

The unicellular green alga Scenedesmus obliquus adapts to different irradiances and wavelengths of light by altering the molecular organization of the photosynthetic apparatus. Regulation occurs on the level of pigment-accumulation, assembly of pigmentprotein complexes and gene-expression. Action spectroscopy revealed the involvement of at least two photoreceptor-systems regulating adaptation antagonistically with markedly different thresholds (Thielmann et ai., 1991;. One of them was a BL-(flavin-type-) receptor, which mediates weak-light adaptation, resulting in increased Chi, LHC II (Humbeck et ai., 1988;Senger and Bauer, 1987) and accumulation of cab-mRNA (Hermsmeier et ai., 1991); the other one was a VL/RL-receptor with action peaks at 404 and 650 nm, inducing high-irradiance responses indicated by decreased amounts of Chi, LHC II, LHCP and cab-mRNA (Hermsmeier et ai., 1991).

Light Adaptation of the Photosynthetic Apparatus of Green Algae

“…Support for the antagonistic blue-and red-light photoreceptors was provided by the evidence of a blue-and red-light regulated cab-gene [34,7]. This is the first evidence that different light qualities can regulate the same gene to express two different photoreceptors.…”

“…5.3). Blue light, like lowlight, induces an increase in the number of pigment systems per electron transfer chain, whereas red light blocks Chl b synthesis and leads to a decreased lightharvesting system together with an increase in the number of reaction centers per electron transfer chain [7,8].…”

“…Algae living in the deeper regions of water-predominant habitats are exposed to a blue light irradiation compared to terrestrial higher plants growing in the shade of other plants with a higher red fraction of light [7]. Adaptation of Scenedesmus to very low light intensities was studied using the two greening mutants C-2A' and CP-Ia-13-y3 [9,10].…”

“…In collaboration with the group of Prof. Webrmeyer we took a closer look at the influence of light and CO2 concentration on the adaptation of the cyanobacterial photosynthetic apparatus [7]. …”

Consequences of light spectra for pigment composition and gene expression in the cryptophyteRhodomonas salina

“…Many studies examining the physiological effects of red and blue spectral habitats exist (e.g. Figueroa et al 1994;Hoham et al 1997;Ullrich et al 1998;Aguilera et al 2000;Korbee et al 2005;Kim et al 2019), and gene expression work has increased over the years, including work with green algae (Hermsmeier et al 1991;Lee et al 2018;Li et al 2020), brown algae (Deng et al 2012;Wang et al 2013), red algae (Lopez-Figueroa 1991Tardu et al 2016), and stramenopiles (Takahashi et al 2007;Losi & Gartner 2008). In many of these gene expression studies, blue wavelengths result in a greater number of upregulated genes than red wavelengths, which we also observed in R. salina.…”