Species- and strain-specific strategies of microalgal strains (desmids, genus Cosmarium, Zygnematophyceae, Streptophyta) as protection against excessive photosynthetically active radiation

• Main Authors: Stamenković, Marija, Bischof, Kai, Hanelt, Dieter
• Format: Conference Object
• Language: English
• Published: Lancaster: The Society for Experimental Biology 2017
• Subjects: Arctic; albedo
• Online Access: http://radar.ibiss.bg.ac.rs/handle/123456789/6789; https://radar.ibiss.bg.ac.rs/bitstream/id/18020/SEB_gothenburg_abstractbook_2017-Stamenkovic.pdf; https://hdl.handle.net/21.15107/rcub_ibiss_6789

We examined the influence of irradiance on protection strategies of four microalgal strain belonging to the genus Cosmarium (Zygnematophyceae, Streptophyta), which were isolated from various climatic zones and cultured long term (>15 years). The photosynthetic behaviour and composition of photosynthetic pigments of the Cosmarium strains were examined under low, moderate and photoinhibitory white light by means of PAM fluorometry, and high-performance liquid chromatography. Generally, the Cosmarium strains displayed the photosynthetic performance and pigment composition corresponding to that of high-light adapted plants and algae. Yet, all the Cosmarium strains demonstrated physiological responses that were consistent with the light intensity prevailing at their source location as concluded from chlorophyll fluorescence and changes of pigment composition, confirming that these responses are genetically preserved. Addition of inhibitors of chloroplast-encoded protein synthesis (chloramphenicol and streptomycin) and violaxanthin de-epoxidase (dithiothreitol) indicated that the Cosmarium strains developed “sun- or shade-plant” protection strategies, in accordance with the climate at their sampling sites. Strikingly, the typical arctic taxon, C. crenatum var. boldtianum, displayed the incomplete violaxanthin cycle yielding an accumulation of antheraxanthin during high light stress, which is considered as an adaptation to occasional high irradiances in the polar zone due to the albedo. Antheraxanthin actively participated in the heat dissipation from PSII centres in C. crenatum, as concluded from a significant positive correlation between non-photochemical quenching and the quantity of antheraxanthin. The species- and strain-specific ecophysiological adaptations discussed in this study may enable desmids to cope with Abstract Book: SEB Gothenburg 2017: Scientific Smärgåsbord; 2017 Jul 3-6; Gothenburg, Sweden. Lancaster: The Society for Experimental Biology; 2017. p. 59.