Different Gene Expression Response of Polish and Australian Raphidiopsis raciborskii Strains to the Chill/Light Stress

Abstract

R. raciborskii is known for growing under wide ranges of temperature and light. In temperate regions, however, low temperature and high light may serve as a stressful condition for invading tropical populations. The genetic basis of R. raciborskii’s adaptation to this combination of stresses are unknown. In this study, the growth rate and the expression of genes that may be crucial in the response to the chill/light stress of two R. raciborskii strains (differing in their climatic origin and toxicity) exposed to low temperature and high light were examined. Results showed that AMU-DH-30, a non CYN (cylindrospermopsin) producing strain isolated from the temperate region, exhibited under stress the upregulation of genes involved in the protein translation (rbp1, nusG, hflX), membrane fluidity (desA), photosynthetic activity (ccr2 and ftsH), and the accumulation of compatible solutes (asd). In contrast, a CYN producing Australian strain CS-505 was not able to adapt quickly and to continue growth during stress conditions. Intriguingly, CS-505 and AMU-DH-30 had a similar ability to resume growth when the stress conditions subsided. Moreover, in strain CS-505 the cyrB gene was significantly upregulated under the stress conditions. The presented results shed new light on the possible mechanisms involved in the response of R.raciborskii to chill/light stress.

Episodic Decrease in Temperature Increases mcy Gene Transcription and Cellular Microcystin in Continuous Cultures of Microcystis aeruginosa PCC 7806

“…In a recent study, Antosiak et al (2020) used Raphidiopsis (Cylindrospermopsis) raciborskii to examine expression of a subset of genes thought to be associated with the acquired chill-light tolerance response. Though the timing of transcriptional change varied, there was a high degree of correspondence between Raphidiopsis and PCC 7806 in genes upregulated by cool temperature.…”

“…This correspondence between distantly related species suggests a conserved response across cyanobacteria. In contrast to Raphidiopsis (Antosiak et al, 2020) and Synechocystis PCC6803 (Li et al, 2012), the ccr2 homolog (cyanobacterial cold resistance) in PCC 7806 did not exhibit notable changes in expression due to decrease in temperature; nor did ccr1 (Yin et al, 2007). Ccr2 is a thylakoid-associated protein (Li et al, 2012) and microcystin is known to preferentially localize near thylakoids in PCC 7806 (Young et al, 2005).…”

Special Issue on Harmful Cyanobacteria and Their Metabolites

“…Australian strains of Raphidiopsis raciborskii they were exposed to chill/light stress [3]. R. raciborskii is an invading cyanobacterial species which grows in various climatic regions with different temperature and light conditions, cf.…”

Recent Advances in the Ecology of Bloom-Forming Raphidiopsis (Cylindrospermopsis) raciborskii: Expansion in China, Intraspecific Heterogeneity and Critical Factors for Invasion

“…The invasion success of R. raciborskii was mainly ascribed to its phenotypic plasticity and growth optimization under different environments [9,[17][18][19][20]. R. raciborskii is tolerant to low and high light intensity and a wide range of temperatures [19,[21][22][23][24][25]. This species has flexible strategies for utilizing various forms of nitrogen (N), such as accumulating nitrogen as cyanophycin [26] and switching to N 2 fixation under N depletion [27][28][29].…”