# Cell Response to Oxidative Stress in Antarctic Filamentous Fungi
## 9 Genetic Basis of Cell Response to Cold Stress  
Research on mycoflora in Antarctica has identified a limited number of endemic psychrophilic species, while the predominant findings indicate the presence of cosmopolitan psychrotolerant taxa [84]. The endemic species have been described as genuine psychrophilic fungi, which can only thrive and reproduce in particular Antarctic conditions [25]. On the other hand, cosmopolitan psychrotolerant fungi are ecotypes that exhibit mesophilic-psychrotolerant behavior, which has developed as an adaptation to the cold Antarctic climate [24]. Various species of the genera _Penicillium_, _Aspergillus_, _Cidosporium_, _Colletotrichum_, _Fusarium_, and _Rhodotorula_, among others, isolated from Antarctica, are characteristic of temperate environments. [PERSON] [6] suggested that fungi in Arctic and Antarctic regions might employ a cold avoidance strategy through recolonization in the spring, utilizing spores or hyphal fragments that have been transported from warmer areas. In addition to the morphological, physiological, and metabolic mechanisms of response against oxidative stress noted above, researchers are looking for molecular genetic evidence for the cold tolerance of such species. [PERSON] et al. [237] reported that the Antarctic rock-inhabiting fungus _Cyromyces antarcticus_, one of the most stress-resistant eukaryotic microorganisms, transcribes a limited part of its genome as a strategy for cold adaptation. Probably, a significant portion of its genome has been silenced due to an 'energy conservation mode'. The identified proteins are predominantly derived from highly conserved protein families that are indispensable for the maintenance of central metabolism, which is critical for growth and recovery after dormancy [238]. A set of novel proteins, characterized by their remarkable resistance to stress, has been evaluated [239]. Additionally, the first assessment of the draft genome did not uncover any substantial variations in the _C. antarcticus_ genome relative to comparative species and mesophilic hyphomycetes [240]. [PERSON] et al. [156] discovered that a significant decrease in temperature (up to 1 \({}^{\circ}\)C) resulted in an increase in the number of proteins in three extremotolerant black fungi: _Coniosporium perforans_, _Exophilala jeanselmei_, and _Friedmanniomyces endolitlicus_. This increase was not observed in the mesophilic hyphomycete _P. chrysogenum_. These variations in the cell response to temperature stress could indicate a distinct strategy to survive suboptimal temperatures. The data on six _Pseudogymnoascus_ spp., collected from different biogeographical regions, presented novel findings regarding the reactions to temperature changes in their habitats [241]. The proteomic study revealed no definitive correlation between protein alterations and the geographical backgrounds of the strains. At the same time, gene ontology analysis indicated a significant presence of proteins associated with various protective strategies, such as the maintenance of protein homeostasis, the regulation of energy metabolism, and the initiation of DNA damage response and repair mechanisms. The research of [PERSON] et al. [173] extended the genetic basis of fungal cell response to oxidative stress. [PERSON] [242] emphasized the relationship between the ecological niche adaptation and the evolution of the fungal genome. The expansion or contraction of orthologous protein families has been described as one of the most straightforward mechanisms by which organisms adapt to harsh environments. Similar gene modifications contributing to the evolution of fungal genomes have been published for the microcolonial black fungus _Saxispiralis lemorum_ MUM 23.14 [243], _Cryptococcus neoformans_ [244], _Mrakia psychrophilia_ [183], etc. The transcriptomic analysis of _M. psychrophilia_ grown at 4 \({}^{\circ}\)C demonstrated up-regulation of the genes responsible for energy metabolism [183].