The Absence of Hydrodynamic Stress Promotes Acquisition of Freezing Tolerance and Freeze-Dependent Asexual Reproduction in the Red Alga 'Bangia' sp. ESS1.

Yoshiki Omuro,Koji Mikami,Ho Viet Khoa

doi:10.3390/plants10030465

Yoshiki Omuro, Koji Mikami + Show 1 more

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https://doi.org/10.3390/plants10030465

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Abstract

The ebb tide causes calm stress to intertidal seaweeds in tide pools; however, little is known about their physiological responses to loss of water movement. This study investigated the effects of static culture of ‘Bangia’ sp. ESS1 at 15 °C on tolerance to temperature fluctuation. The freezing of aer-obically cultured thalli at −80 °C for 10 min resulted in the death of most cells. By contrast, statically cultured thalli acquired freezing tolerance that increased cell viability after freeze–thaw cycles, although they did not achieve thermotolerance that would enable survival at the lethal temperature of 32 °C. Consistently, the unsaturation of membrane fatty acids occurred in static culture. Notably, static culture of thalli enhanced the release of asexual spores after freeze-and-thaw treatment. We conclude that calm stress triggers both the acquisition of freezing tolerance and the promotion of freezing-dependent asexual reproduction. These findings provide novel insights into stress toler-ance and the regulation of asexual reproduction in Bangiales.

Highlights

Bangiales is an order of red algae characterized by thalli with a filamentous or leafy shape [1,2]
We here demonstrated that calm stress promotes the acquisition of freezing tolerance and an increase in the unsaturation of membrane fatty acids, which enables survival upon
We here demonstrated that calm stress promotes the acquisition of freezing tolerance and an increase in the unsaturation of membrane fatty acids, which enables survival upon exposure to −80 ◦C in ‘Bangia’ sp

Summary

Introduction

Bangiales is an order of red algae characterized by thalli with a filamentous or leafy shape [1,2] These seaweeds are sessile multicellular organisms that live in intertidal regions, where temperature, salinity, and nutritional conditions usually fluctuate. A similar phenomenon has been observed in microalgae [17] These findings suggest that the ability to acquire freezing tolerance by exposure to environmental stresses other than low temperature might be conserved among photosynthetic organisms. It has not yet been examined whether cold acclimation is established by such a cross-tolerance mechanism in macroalgae

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