Spatiotemporal patterns of intracellular Ca2+ signalling govern hypo-osmotic stress resilience in marine diatoms

Helliwell, KE, Kleiner, FH, Hardstaff, Hayley, Chrachri, A, Gaikwad, T, Salmon, D, Smirnoff, N, Wheeler, G and Brownlee, C 2021 Spatiotemporal patterns of intracellular Ca2+ signalling govern hypo-osmotic stress resilience in marine diatoms. New Phytologist, 230 (1). 155-170. https://doi.org/10.1111/nph.17162

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Abstract/Summary

Diatoms are globally important phytoplankton that dominate coastal and polar-ice assemblages. These environments exhibit substantial changes in salinity over dynamic spatiotemporal regimes. Rapid sensory systems are vital to mitigate the harmful consequences of osmotic stress. Population-based analyses have suggested that Ca2+ signalling is involved in diatom osmotic sensing. However, mechanistic insight of the role of osmotic Ca2+ signalling is limited. Here, we show that Phaeodactylum Ca2+ elevations are essential for surviving hypo-osmotic shock. Moreover, employing novel single-cell imaging techniques we have characterised real-time Ca2+ signalling responses in single diatom cells to environmental osmotic perturbations. We observe that intracellular spatiotemporal patterns of osmotic-induced Ca2+ elevations encode vital information regarding the nature of the osmotic stimulus. Localised Ca2+ signals evoked by mild or gradual hypo-osmotic shocks are propagated globally from the apical cell tips, enabling fine-tuned cell volume regulation across the whole cell. Finally, we demonstrate that diatoms adopt Ca2+ -independent and dependent mechanisms for osmoregulation. We find that efflux of organic osmolytes occurs in a Ca2+ -independent manner, but this response is insufficient to mitigate cell damage during hypo-osmotic shock. By comparison, Ca2+-dependent signalling is necessary to prevent cell bursting via precise coordination of K+ transport, and therefore is likely to underpin survival in dynamic osmotic environments

Item Type:	Publication - Article
Additional Keywords:	Algae, Ca2+signalling, diatoms, environmental sensing, osmotic stress, Phaeodactylum, R-GECO1, signalling
Subjects:	Marine Sciences
Divisions:	Marine Biological Association of the UK > Marine Microbiome
Depositing User:	Emily Smart
Date made live:	28 Sep 2021 14:39
Last Modified:	09 Feb 2024 17:08
URI:	https://plymsea.ac.uk/id/eprint/9385

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