Effect of Temperature on Polyamine Oxidase Genes in Skeletonema dohrnii

Abstract

In our experiments, we investigated the effect of temperature on diatom polyamine metabolism using Skeletonema dohrnii as an experimental algal species. We set three different temperature conditions for incubation and selected Skeletonema dohrnii in the exponential growth period, and analyzed basic physiological parameters, polyamine composition and content, and polyamine oxidase (PAO) gene expression at different temperatures. The results showed that low temperatures led to a decrease in growth rate, an increase in biogenic silica content, an increase in the content of putrescine and spermine, a decrease in the concentration of spermidine, and a down-regulation of PAO gene expression. In addition, high temperature led to an increase in growth rate, a significant change in the concentration of putrescine and spermine, and an increase in spermidine. These findings suggest that changes in temperature affect the growth rate of algae, low temperature increases the biogenic silica content of diatoms, different temperature stresses lead to different kinds of polyamine changes in diatoms, and the PAO gene may play a role in regulating the response of algae to temperature changes. This study lays a foundation for further exploration of the function of the PAO gene in Skeletonema dohrnii.

Keywords: abiotic stress; diatom; polyamine metabolism.

Figure 1

A simple pathway for polyamine anabolism in microalgae (adapted from Miguel A. Blázquez [29]).

Figure 2

Physiological traits of Skeletonema dohrnii cultured under different temperature conditions. (A): specific growth rate of Skeletonema dohrnii at different temperatures; (B): Fv/Fm of Skeletonema dohrnii at different temperatures; (ns indicates no significance; * indicates p < 0.05; ** indicates p < 0.01; *** indicates p < 0.001).

Figure 3

Chlorophyll a content of Skeletonema dohrnii cultured under different temperature conditions (ns indicates not significant).

Figure 4

Biosilica content of Skeletonema dohrnii cultured under different temperature conditions. (A): Intracellular silica content of Skeletonema dohrnii at different temperatures; (B): Cell wall silica content of Skeletonema dohrnii at different temperatures (ns indicates non-significant; * indicates p < 0.05; ** indicates p < 0.01).

Figure 5

Concentration of polyamines in Skeletonema dohrnii cultured under different temperature conditions. (A): putrescine content of Skeletonema dohrnii at different temperatures; (B): spermine content of Skeletonema dohrnii at different temperatures; (C): spermidine content of Skeletonema dohrnii at different temperatures (ND indicates none detected; ns indicates non-significance; * indicates p < 0.05; *** indicates p < 0.001).

Figure 6

Expression of polyamine oxidase gene in Skeletonema dohrnii cultured at different temperatures (** indicates p < 0.01; **** indicates p < 0.0001).