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Abiotic stress is the negative impact of non-living factors on the living organisms in a specific environment. The non-living variable must influence the environment beyond its normal range of variation to adversely affect the population performance or individual physiology of the organism in a significant way.
A halophile is an extremophile that thrives in high salt concentrations. In chemical terms, halophile refers to a Lewis acidic species that has some ability to extract halides from other chemical species.
Biosalinity is the study and practice of using saline (salty) water for irrigating agricultural crops.
A halophyte is a salt-tolerant plant that grows in soil or waters of high salinity, coming into contact with saline water through its roots or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. The word derives from Ancient Greek ἅλας (halas) 'salt' and φυτόν (phyton) 'plant'. Halophytes have different anatomy, physiology and biochemistry than glycophytes. An example of a halophyte is the salt marsh grass Spartina alterniflora. Relatively few plant species are halophytes—perhaps only 2% of all plant species. Information about many of the earth's halophytes can be found in the ehaloph database.
Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean. It can also come about through artificial processes such as irrigation and road salt.
Dunaliella salina is a type of halophile unicellular green algae especially found in hypersaline environments, such as salt lakes and salt evaporation ponds. Known for its antioxidant activity because of its ability to create large amount of carotenoids, it is responsible for most of the primary production in hypersaline environments worldwide, and is also used in cosmetics and dietary supplements.
A brine pool, sometimes called an underwater lake, deepwater or brine lake, is a volume of brine collected in a seafloor depression. The pools are dense bodies of water that have a salinity that is three to eight times greater than the surrounding ocean. Brine pools are commonly found below polar sea ice and in the deep ocean. Those below sea ice form through a process called brine rejection. For deep-sea brine pools, salt is necessary to increase the salinity gradient. The salt can come from one of two processes: the dissolution of large salt deposits through salt tectonics or geothermally heated brine issued from tectonic spreading centers.
Aureobasidium pullulans is a ubiquitous and generalistic black, yeast-like fungus that can be found in different environments. It is well known as a naturally occurring epiphyte or endophyte of a wide range of plant species without causing any symptoms of disease. A. pullulans has a high importance in biotechnology for the production of different enzymes, siderophores and pullulan. Furthermore, A. pullulans is used in biological control of plant diseases, especially storage diseases.
Dunaliella is a single-celled, photosynthetic green alga, that is characteristic for its ability to outcompete other organisms and thrive in hypersaline environments. It is mostly a marine organism, though there are a few freshwater species that tend to be more rare. It is a genus in which certain species can accumulate relatively large amounts of β-carotenoids and glycerol in very harsh growth conditions consisting of high light intensities, high salt concentrations, and limited oxygen and nitrogen levels, yet is still very abundant in lakes and lagoons all around the world.
Hortaea werneckii is a species of yeast in the family Teratosphaeriaceae. It is a black yeast that is investigated for its remarkable halotolerance. While the addition of salt to the medium is not required for its cultivation, H. werneckii can grow in close to saturated NaCl solutions. To emphasize this unusually wide adaptability, and to distinguish H. werneckii from other halotolerant fungi, which have lower maximum salinity limits, some authors describe H. werneckii as "extremely halotolerant".
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes to keep the body fluids from becoming too diluted or concentrated. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher the osmotic pressure of a solution, the more water tends to move into it. Pressure must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water by osmosis from the side containing pure water.
The Wallemiomycetes are a class of fungi in the division Basidiomycota. It consists of the single order Wallemiales, containing the single family Wallemiaceae, which in turn contains the single genus Wallemia. The phylogenetic origin of the lineage was placed to various parts of Basidiomycota, but according to the analysis of a larger dataset it is a sister group of Agaricomycotina. The genus contains species of xerophilic molds that are found worldwide. The seven described species are distinguished by conidial size, xerotolerance, halotolerance, chaotolerance, growth temperature regimes, extracellular enzyme activity profiles, and secondary metabolite patterns. They are typically isolated from low-moisture foods, indoor air dust, salterns and soil. W. sebi is thought to be one of the causes of the hypersensitivity pneumonitis known as the farmer's lung disease, but since the other species were recognised and separated from W. sebi only recently, their role in the disease cannot be excluded.
Mycosporine-like amino acids (MAAs) are small secondary metabolites produced by organisms that live in environments with high volumes of sunlight, usually marine environments. The exact number of compounds within this class of natural products is yet to be determined, since they have only relatively recently been discovered and novel molecular species are constantly being discovered; however, to date their number is around 30. They are commonly described as “microbial sunscreens” although their function is believed not to be limited to sun protection. MAAs represent high potential in cosmetics, and biotechnological applications. Indeed, their UV-absorbing properties would allow to create products derived from natural photoprotectors, potentially harmless to the environment and efficient against UV damage.
Black yeasts, sometimes also black fungi, dematiaceous fungi, microcolonial fungi or meristematic fungi is a diverse group of slow-growing microfungi which reproduce mostly asexually. Only few genera reproduce by budding cells, while in others hyphal or meristematic (isodiametric) reproduction is preponderant. Black yeasts share some distinctive characteristics, in particular a dark colouration (melanisation) of their cell wall. Morphological plasticity, incrustation of the cell wall with melanins and presence of other protective substances like carotenoids and mycosporines represent passive physiological adaptations which enable black fungi to be highly resistant against environmental stresses. The term "polyextremotolerance" has been introduced to describe this phenotype, an example of which is the species Aureobasidium pullulans. Presence of 1,8-dihydroxynaphthalene melanin in the cell wall confers to the microfungi their characteristic olivaceous to dark brown/black colour.
Wallemia sebi is a xerophilic fungus of the phylum Basidiomycota.
Wallemia ichthyophaga is one of the three species of fungi in the genus Wallemia, which in turn is the only genus of the class Wallemiomycetes. The phylogenetic origin of the lineage was placed to various parts of Basidiomycota, but according to the analysis of larger datasets it is a (495-million-years-old) sister group of Agaricomycotina. Although initially believed to be asexual, population genomics found evidence of recombination between strains and a mating type locus was identified in all sequenced genomes of the species.
Previously classified under the species complex Aureobasidium pullulans, Aureobasidium subglaciale is a black yeast-like, extremophile, ascomycete fungus that is found in extreme cold habitats. The species was originally isolated from subglacial ice of arctic glaciers. The first isolate of this species was obtained from subglacial ice of the Norwegian island Spitsbergen, one of the coldest places inhabited by humans. of Genomic data collected from specimens in the Aureobasidium pullulans complex justified distinction of four different species
Salt tolerance of crops is the maximum salt level a crop tolerates without losing its productivity while it is affected negatively at higher levels. The salt level is often taken as the soil salinity or the salinity of the irrigation water.
Crop tolerance to seawater is the ability of an agricultural crop to withstand the high salinity induced by irrigation with seawater, or a mixture of fresh water and seawater. There are crops that can grow on seawater and demonstration farms have shown the feasibility. The government of the Netherlands reports a breakthrough in food security as specific varieties of potatoes, carrots, red onions, white cabbage and broccoli appear to thrive if they are irrigated with salt water.
Fungal genomes are among the smallest genomes of eukaryotes. The sizes of fungal genomes range from less than 10 Mbp to hundreds of Mbp. The average genome size is approximately 37 Mbp in Ascomycota, 47 Mbp in Basidiomycota and 75 Mbp in Oomycota. The sizes and gene numbers of the smallest genomes of free-living fungi such as those of Wallemia ichthyophaga, Wallemia mellicola or Malassezia restricta are comparable to bacterial genomes. The genome of the extensively researched yeast Saccharomyces cerevisiae contains approximately 12 Mbp and was the first completely sequenced eukaryotic genome. Due to their compact size fungal genomes can be sequenced with less resources than most other eukaryotic genomes and are thus important models for research. Some fungi exist as stable haploid, diploid, or polyploid cells, others change ploidy in response to environmental conditions and aneuploidy is also observed in novel environments or during periods of stress.
References
- ↑ Walter Larcher (2001) Physiological Plant Ecology ISBN 3-540-43516-6
- ↑ Margesin, R.; Schinner, F. (2001). "Potential of halotolerant and halophilic microorganisms for biotechnology". Extremophiles: Life Under Extreme Conditions. 5 (2): 73–83. doi:10.1007/s007920100184. PMID 11354458. S2CID 22371046.
- ↑ Gupta, Bhaskar; Huang, Bingru (3 April 2014). "Mechanism of Salinity Tolerance in Plants: Physiological, Biochemical, and Molecular Characterization". International Journal of Genomics . 2014: 701596. doi: 10.1155/2014/701596 . PMC 3996477 . PMID 24804192.
- ↑ Dieter Häussinger and Helmut Sies (2007) Osmosensing and Osmosignaling, Academic Press, 579 pages ISBN 0-12-373921-7
- ↑ C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham
- ↑ Gostinčar, C.; Grube, M.; De Hoog, S.; Zalar, P.; Gunde-Cimerman, N. (2010). "Extremotolerance in fungi: Evolution on the edge". FEMS Microbiology Ecology. 71 (1): 2–11. doi: 10.1111/j.1574-6941.2009.00794.x . PMID 19878320.
- ↑ Zajc, J.; Zalar, P.; Plemenitaš, A.; Gunde-Cimerman, N. (2012). "The Mycobiota of the Salterns". Biology of Marine Fungi. Progress in Molecular and Subcellular Biology. Vol. 53. pp. 133–158. doi:10.1007/978-3-642-23342-5_7. ISBN 978-3-642-23341-8. PMID 22222830.
- ↑ Gunde-Cimerman, N.; Ramos, J.; Plemenitaš, A. (2009). "Halotolerant and halophilic fungi". Mycological Research. 113 (11): 1231–1241. doi:10.1016/j.mycres.2009.09.002. PMID 19747974.
- ↑ Gostinčar, C.; Lenassi, M.; Gunde-Cimerman, N.; Plemenitaš, A. (2011). Fungal Adaptation to Extremely High Salt Concentrations. Advances in Applied Microbiology. Vol. 77. pp. 71–96. doi:10.1016/B978-0-12-387044-5.00003-0. ISBN 9780123870445. PMID 22050822.
