Phycologia / Photophysiological investigations of the temperature stress responses of Zygnema spp (Zygnematophyceae) from subpolar and polar habitats (Iceland, Svalbard)

• Published in: Phycologia
• Main Authors: Permann, Charlotte, Pierangelini, Mattia, Remias, Daniel, Lewis, Louise A., Holzinger, Andreas
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis 2022
• Subjects: climate change; Green algae; Photosynthesis; rbcL phylogeny; Streptophyta; Transmission electron microscopy; Svalbard; Iceland
• Online Access: https://doi.org/10.1080/00318884.2022.2043089; https://diglib.uibk.ac.at/doi/10.1080/00318884.2022.2043089; https://resolver.obvsg.at/urn:nbn:at:at-ubi:3-36652

Zygnematophyceae are main primary producers in polar hydro-terrestrial habitats, characterized by extreme abiotic conditions. They are expected to be strongly impacted by climate change, leading to threats to subpolar and polar ecosystems. Two isolates of Zygnema from a subpolar (Iceland, Zygnema sp. I) and a polar Island (Svalbard, Zygnema sp. B) were compared by their photophysiological performance and phenolic content. A phylogenetic analysis was performed in a newly isolated Zygnema I where also morphology and ultrastructure were characterized. The rbcL sequence of the Icelandic Zygnema I was identical to that of Zygnema V, previously isolated from Svalbard, and phylogenetic analysis placed this strain into Zygnema clade 2. Average width of vegetative filaments (28 ± 0.7 µm) and ultrastructure was similar to closely related Zygnema strains. Zygnema I and Zygnema B were exposed to three different treatment temperatures (15, 20 and 25°C) for two weeks, then photophysiological parameters and cellular phenol contents were acquired. The maximum electron transport rate increased significantly with elevated temperatures, but non-photochemical quenching did not change. Net photosynthetic oxygen production was higher in Zygnema B, but decreased in both strains from 10 to 15°C measuring temperature. Zygnema I showed a significant decrease between 15/25°C-treated cultures above 20°C measuring temperature. The phenolic content did not change significantly with experimental treatments, the spectral absorption at 350 nm was significantly lower in Zygnema B when compared with Zygnema I. Taken together our results indicate that Zygnema B and Zygnema I cannot adapt to elevated temperatures. Version of record