Polyols-related gene expression is affected by cyclic desiccation in lichen microalgae

• Published in: Environmental and experimental botany Vol. 185; p. 104397
• Main Authors: Hell, Aline F., Gasulla, Francisco, González-Houcarde, Maria, Pelegrino, Milena T., Seabra, Amedea B., del Campo, Eva M., Casano, Leonardo M., Centeno, Danilo C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2021
• Subjects: biochemical pathways; botany; Coccomyxa; correlation; Desiccation tolerance; drought tolerance; gene expression; genes; habitats; Lichen microalga; lichens; memory; metabolism; metabolites; microalgae; myo-inositol; Nitric oxide; solutes; stress response; synthesis; transcription (genetics); Transcriptional expression; Trebouxia; water; water content; Trebouxia; Desiccation tolerance; Coccomyxa; Lichen microalga; Transcriptional expression; Nitric oxide
• ISSN: 0098-8472; 1873-7307
• DOI: 10.1016/j.envexpbot.2021.104397

•Expression of myo-inositol and raffinose-related genes is modulated by cyclic D/R.•NO concentration is induced by cyclic D/R, with a burst during rewetting.•Polyols play an important role on the osmoregulation.•NO signaling assists on the regulation of the osmoprotectants.•A primed metabolic state is suggested to occur. The accumulation of compatible solutes, as sugar and polyols, as a response to stress is a widely biochemical adaptation. However, the signaling process involved in this regulation remains unclear. Lichens and their microalgae have to cope with a variety of stresses associated with sudden changes in water content during daily cycles of desiccation-rehydration (D/R). In this way, we hypothesized: (1) the differences in desiccation tolerance among lichen-forming microalgae could be associated with species-specific differences in their polyol metabolism and (2) the nitric oxide (NO), as a signaling molecule, could assist the regulation of the expression of polyol-related genes in these organisms. Therefore, we carried out a comparative analysis of the transcriptional expression of key genes involved in the synthesis of polyols and metabolite levels, along with the cellular concentration of NO in isolated lichen microalgae during consecutive daily cycles of D/R and correlated the results with the polyol profile and NO measurements. Two microalgae were employed, Trebouxia sp. TR9 (TR9) and Coccomyxa simplex (Csol), obtained from lichens subjected to different water availability in their natural habitat. Our results revealed that, in both microalgae, the expression of myo-inositol and raffinose-related genes is modulated by cyclic D/R. Although, genes seem more prone to be transcriptionally upregulated by cyclic D/R in Csol than in TR9, indicating a more inducible defensive response in Csol in contrast with a constitutive defense system in TR9. Correlation analysis provided evidences that NO may act as a signaling molecule, through the modulation of polyol biosynthetic pathway and may be related to a primed memory state, by assisting in the rapidly and more precise metabolic response to subsequent D/R cycles.