Abstract Title

Photosynthetic efficiency in Polish and Australian Raphidiopsis raciborskii strains

Start Date

24-5-2022 10:15 AM

End Date

24-5-2022 10:30 AM

Abstract

Raphidiopsis raciborskii, as a potentially toxic, invasive cyanobacteria has attracted great attention. Worldwide distribution could have contributed to its phenotypic plasticity and even the formation of ecotypes adapted to the local environment. To determine mechanisms responsible for the omnipresence of R. raciborskii, photosynthetic efficiency in several strains differing in origin and toxicity has been investigated. Three non-toxic Polish strains and two toxic Australian strains were grown under standardized light and temperature conditions. Concentration of photosynthetic pigments, qualitative and quantitative analysis of carotenoid composition, and photosynthetic performance (chlorophyll fluorescence in vivo) were analysed. No significant differences between strains were observed in the photosystem II quantum efficiency (Fv/Fm), the photochemical (qP) and non-photochemical quenching (NPQ) and dark and light levels of plastoquinone reduction. Nonetheless, a positive correlation between Fv/Fm and overall NPQ was found. The phycocyanin concentration was negatively correlated with the carotenoid concentration in all five examined strains. Furthermore, in four strains roughly one third of pigments consisted of myxoxanthophylls. The ability to accumulate pigments involved both in light harvesting and photoprotection may contribute to the optimization of photosynthetic efficiency of investigated R. raciborskii strains in different environmental conditions. Documented parameters could not be ascribed to the difference in growth conditions, but could result from variations in their genetics.

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May 24th, 10:15 AM May 24th, 10:30 AM

Photosynthetic efficiency in Polish and Australian Raphidiopsis raciborskii strains

Raphidiopsis raciborskii, as a potentially toxic, invasive cyanobacteria has attracted great attention. Worldwide distribution could have contributed to its phenotypic plasticity and even the formation of ecotypes adapted to the local environment. To determine mechanisms responsible for the omnipresence of R. raciborskii, photosynthetic efficiency in several strains differing in origin and toxicity has been investigated. Three non-toxic Polish strains and two toxic Australian strains were grown under standardized light and temperature conditions. Concentration of photosynthetic pigments, qualitative and quantitative analysis of carotenoid composition, and photosynthetic performance (chlorophyll fluorescence in vivo) were analysed. No significant differences between strains were observed in the photosystem II quantum efficiency (Fv/Fm), the photochemical (qP) and non-photochemical quenching (NPQ) and dark and light levels of plastoquinone reduction. Nonetheless, a positive correlation between Fv/Fm and overall NPQ was found. The phycocyanin concentration was negatively correlated with the carotenoid concentration in all five examined strains. Furthermore, in four strains roughly one third of pigments consisted of myxoxanthophylls. The ability to accumulate pigments involved both in light harvesting and photoprotection may contribute to the optimization of photosynthetic efficiency of investigated R. raciborskii strains in different environmental conditions. Documented parameters could not be ascribed to the difference in growth conditions, but could result from variations in their genetics.