Mutualistic symbioses have contributed to major transitions in the evolution of life. Here, we investigate the evolutionary history and the molecular innovations at the origin of lichens, which are a symbiosis established between fungi and green algae or cyanobacteria. We de novo sequence the genomes or transcriptomes of 12 lichen algal symbiont (LAS) and closely related non-symbiotic algae (NSA) to improve the genomic coverage of Chlorophyte algae. We then perform ancestral state reconstruction and comparative phylogenomics. We identify at least three independent gains of the ability to engage in the lichen symbiosis, one in Trebouxiophyceae and two in Ulvophyceae, confirming the convergent evolution of the lichen symbioses. A carbohydrate-active enzyme from the glycoside hydrolase 8 (GH8) family was identified as a top candidate for the molecular-mechanism underlying lichen symbiosis in Trebouxiophyceae. This GH8 was acquired in lichenizing Trebouxiophyceae by horizontal gene transfer, concomitantly with the ability to associate with lichens fungal symbionts (LFS) and is able to degrade polysaccharides found in the cell wall of LFS. These findings indicate that a combination of gene family expansion and horizontal gene transfer provided the basis for lichenization to evolve in chlorophyte algae.

• MeSH
• biologická evoluce MeSH
• Chlorophyta * genetika   MeSH
• fylogeneze * MeSH
• genomika MeSH
• glykosidhydrolasy genetika   metabolismus   MeSH
• lišejníky * genetika   mikrobiologie   MeSH
• molekulární evoluce MeSH
• přenos genů horizontální MeSH
• symbióza * genetika   MeSH
• transkriptom MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glykosidhydrolasy MeSH

Alcobiosis, the symbiosis of algae and corticioid fungi, frequently occurs on bark and wood. Algae form a layer in or below fungal basidiomata reminiscent of the photobiont layer in lichens. Identities of algal and fungal partners were confirmed by DNA barcoding. Algal activity was examined using gas exchange and chlorophyll fluorescence techniques. Carbon transfer from algae to fungi was detected as 13C, assimilated by algae, transferred to the fungal polyol. Nine fungal partners scattered across Agaricomycetes are associated with three algae from Trebouxiophycae: Coccomyxa sp. with seven fungal species on damp wood, Desmococcus olivaceus and Tritostichococcus coniocybes, both with a single species on bark and rain-sheltered wood, respectively. The fungal partner does not cause any obvious harm to the algae. Algae enclosed in fungal tissue exhibited a substantial CO2 uptake, but carbon transfer to fungal tissues was only detected in the Lyomyces-Desmococcus alcobiosis where some algal cells are tightly enclosed by hyphae in goniocyst-like structures. Unlike lichen mycobionts, fungi in alcobioses are not nutritionally dependent on the algal partner as all of them can live without algae. We consider alcobioses to be symbioses in various stages of co-evolution, but still quite different from true lichens.

• MeSH
• alarminy MeSH
• biologický transport MeSH
• ekzém * MeSH
• hyfy MeSH
• keratóza * MeSH
• lišejníky * MeSH
• uhlík MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alarminy MeSH
• uhlík MeSH

Simple trichal types constitute a group of cyanobacteria with an abundance of novel, often cryptic taxa. Here, we investigated material collected from wet surface-soil in a saline environment in Petchaburi Province, central Thailand. A morphological comparison of the isolated strain with similar known species, as well as its phylogenetic and species delimitation analyses based on the combined datasets of other related organisms, especially simple trichal cyanobacteria, revealed that the material of this study represented an independent taxon. Using a multifaceted method, we propose that this material represents a new genus, Thainema gen. nov., belonging to the family Leptolyngbyaceae, with the type species Thainema salinarum sp. nov. This novel taxon shares similar ecological habitats with strains previously placed in the same lineage.

• MeSH
• ekosystém MeSH
• sinice klasifikace   genetika   izolace a purifikace   MeSH
• techniky typizace bakterií MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Thajsko MeSH

A terrestrial green microalga was isolated at Ås, in Akershus County, Norway. The strain corresponded to a coccoid chlorophyte. Morphological characteristics by light and electron microscopy, in conjunction with DNA amplification and sequencing of the 18 s rDNA gene and ITS sequences, were used to identify the microalgae. The characteristics agree with those of the genus Coelastrella defined by Chodat, and formed a sister group with the recently described C. thermophila var. globulina. Coelastrella is a relatively small numbered genus that has not been observed in continental Norway before; there are no previous cultures available in collections of Norwegian strains. Gas chromatography analyses of the FAME-derivatives showed a high percentage of polyunsaturated fatty acids (44-45%) especially linolenic acid (C18:3n3; 30-34%). After the stationary phase, the cultures were able to accumulate several carotenoids as neoxanthin, pheophytin a, astaxanthin, canthaxanthin, lutein, and violaxanthin. Due to the scarcity of visual characters suitable for diagnostic purposes and the lack of DNA sequence information, there is a high possibility that species of this genus have been neglected in local environmental studies, even though it showed interesting properties for algal biotechnology.

• Klíčová slova
• 18S rDNA, Algae phylogeny, Electron microscopy, Fatty acids, ITS, Strain FGS-001,
• MeSH
• biologické pigmenty analýza   MeSH
• biotechnologie MeSH
• Chlorophyta klasifikace   cytologie   genetika   MeSH
• druhová specificita MeSH
• feofytiny analýza   MeSH
• fylogeneze * MeSH
• karotenoidy analýza   MeSH
• kyselina alfa-linolenová analýza   MeSH
• mastné kyseliny analýza   MeSH
• mikrořasy klasifikace   cytologie   genetika   izolace a purifikace   MeSH
• ribozomální DNA MeSH
• RNA ribozomální 18S genetika   MeSH
• xanthofyly MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Norsko MeSH
• Názvy látek
• astaxanthine MeSH Prohlížeč
• biologické pigmenty MeSH
• feofytiny MeSH
• karotenoidy MeSH
• kyselina alfa-linolenová MeSH
• mastné kyseliny MeSH
• neoxanthin MeSH Prohlížeč
• ribozomální DNA MeSH
• RNA ribozomální 18S MeSH
• violaxanthin MeSH Prohlížeč
• xanthofyly MeSH

The aim of this study was to reveal the taxonomic position and phylogenetic relationships of the dominant planktic algae in two acid metal-rich lakes of different origin (Hromnice Lake and Plešné Lake, Czech Republic) and to investigate their morphology and ultrastructure under natural and laboratory conditions. Phylogenetic analyses (18S rRNA and ITS-2) revealed that the strain isolated from Hromnice Lake belongs to the species Coccomyxa elongata, while Coccomyxa from Plešné Lake was described as a new species C. silvae-gabretae. It is the first evidence that representatives of this genus are capable of becoming the dominant primary producers in the extreme environment of acid lakes with an increased supply of phosphorus. There were clear differences in cell morphology under different growth conditions, revealing the high phenotypic plasticity of the strains. The ability to change the morphology may help the cells of Coccomyxa to survive harsh conditions in the aforementioned acid lakes.

• Klíčová slova
• 18S rRNA, Acid lakes, Coccomyxa, Ecology, ITS-2, Morphology, Phylogeny, Ultrastructure,
• MeSH
• Chlorophyta * klasifikace   genetika   MeSH
• fylogeneze * MeSH
• fytoplankton * klasifikace   genetika   MeSH
• jezera mikrobiologie   MeSH
• mikrobiologie vody * MeSH
• RNA ribozomální 18S genetika   MeSH
• RNA rostlin genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA ribozomální 18S MeSH
• RNA rostlin MeSH