The response of Asterochloris erici (Ahmadjian) Skaloud et Peksa to desiccation: a proteomic approach

Abstract

The study of desiccation tolerance of lichens, and of their chlorobionts in particular, has frequently focused on the antioxidant system that protects the cell against photo-oxidative stress during dehydration/rehydration cycles. In this study, we used proteomic and transcript analyses to assess the changes associated with desiccation in the isolated phycobiont Asterochloris erici. Algae were dried either slowly (5-6 h) or rapidly (<60 min), and rehydrated after 24 h in the desiccated state. To identify proteins that accumulated during the drying or rehydration processes, we employed two-dimensional (2D) difference gel electrophoresis (DIGE) coupled with individual protein identification using trypsin digestion and liquid chromatography-tandem mass spectrometry (LC-MS/ MS). Proteomic analyses revealed that desiccation caused an increase in relative abundance of only 11-13 proteins, regardless of drying rate, involved in glycolysis, cellular protection, cytoskeleton, cell cycle, and targeting and degradation. Transcripts of five Hsp90 and two b-tubulin genes accumulated primarily at the end of the dehydration process. In addition, transmission electron microscopy (TEM) images indicate that ultrastructural cell injuries, perhaps resulting from physical or mechanical stress rather than metabolic damage, were more intense after rapid dehydration. This occurred with no major change in the proteome. These results suggest that desiccation tolerance of A. erici is achieved by constitutive mechanisms.

Contrasting strategies used by lichen microalgae to cope with desiccation–rehydration stress revealed by metabolite profiling and cell wall analysis

“…These arguments led to the notion that DT in lichens and especially in terrestrial microalgae is a constitutive strategy. The high amount of diverse protective sugars and their derivatives (Gustavs et al ., ), and the apparently small proteome changes during desiccation (Gasulla et al ., ) in some Trebouxiophyceae algae further support this contention. However, knowledge of the molecular, biochemical and ultrastructural bases of the physiological response to desiccation–rehydration in green algae remains scarce (Holzinger and Karsten, ).…”

The complexity of symbiotic interactions influences the ecological amplitude of the host: A case study inStereocaulon(lichenized Ascomycota)

“…In case of two other phycobiont genera, these problems have not occurred because of more acceptable species‐level lineages of mycobionts, including several common ones. Tolerance of Vulcanochloris towards extreme drought should be confirmed by culture experiments and compared with that of Asterochloris (e.g., Gasulla et al., ) or other trebouxiophycean phycobionts (Candotto‐Carniel et al., ; Centeno, Hell, Braga, del Campo, & Casano, ).…”

“…of Vulcanochloris towards extreme drought should be confirmed by culture experiments and compared with that of Asterochloris (e.g., Gasulla et al, 2013) or other trebouxiophycean phycobionts (Candotto-Carniel et al, 2016;Centeno, Hell, Braga, del Campo, & Casano, 2016).…”

Temperature-dependent growth rate and photosynthetic performance of Antarctic symbiotic alga Trebouxia sp. cultivated in a bioreactor

“…For cultivation of lichen symbiotic algae, a variety of liquid media and volumes of cell culture flasks is used. This approach was applied in the experiments studying dehydration (Wieners et al 2012, Gasulla et al 2013, and oxidative stress effects (Del Hoyo et al 2011). Recently, photobioreactors (PBRs) are used in cultivation of numerous algal species.…”