Microthamniales

Abstract: PROBLEM TO BE SOLVED: To find out physiological activity of an extract of algae or plants, and provide the same to new applications.SOLUTION: This LTBP-4 production promotor includes an extract of algae or plants as an effective ingredient. As the preferable extract of algae or plants, there are illustrated red algae belonging to orders Acrochaetiales, Porphyridiales, Bangiales, Nemalionales, Erythropeltidales, Compsopogonales, Cryptonemiales, etc.; green algae belonging to orders Volvocida, Sphaeropleales, Oedogoniales, Chaetophorales, Chaetopeltidales, Chlorellales, Microthamniales, Trebouxiophyceae, Schizogoniales, Mamiellales, etc.; and brown algae belonging to orders Ralfsiales, Dyctyotales, Chordariales, Scytosiphonales, Cutleriales, Sporochnales, Desmarestiales, Laminariales, Ishigeales, or Fucales, etc.; and Labiatae family, Leguminosae family, Rhamnaceae family, Actinidiaceae family, Polygonaceae family, Vilaceae family, Compositae family, Gentianaceae family, etc.

Abstract: The green algal genus Microthamnion (Microthamniales, Trebouxiophyceae) has been extensively studied, but the question of species delimitation remained a matter of controversy. The morphological traits used to discriminate species in Microthamnion have shown to be quite polymorphic, and the restriction enzyme analysis performed in a first molecular attempt does no longer meet modern standards. The present study used a detailed molecular approach and combined several methods to clarify the matter of species delimitation on a molecular level. A multi-gene alignment comprising the nuclear-encoded 18S, and 28S rRNA genes, and the ITS2 molecule, as well as the plastid-encoded rbcL gene was assembled and used for concatenated phylogenetic analyses. The 74 Microthamnion strains investigated in this study fell into four monophyletic clades (one with a distinct subdivision) and nine longbranched lineages, which are assumed to correspond to species level. An apomorphy analysis was performed in order to find non-homoplasious synapomorphies (NHSs), and thus unique molecular signatures, for the clades and lineages inferred from the phylogeny. In a novel approach that interpreted molecular data in an alternative way, these NHSs and other ‘phenotypic molecular characters’ were compiled in a data matrix and used for a parsimony tree reconstruction. The clade boundaries and lineages inferred from the Microthamnion phylogeny were confirmed by both, unique molecular signatures and the tree based on all phenotypic molecular characters, resulting in 14 putative species delineated by molecular methods.

Abstract: Eight complete nuclear-encoded small-subunit ribosomal RNA (18S rRNA) gene sequences were determined for four genera of the Microthamniales (Pleurastrophyceae) and for Gloeotilopsis planctonica Iyengar & Philipose (Ulvophyceae, Ulotrichales) to investigate evolutionary relationships within the Microthamniales and the taxonomic position of this order within the green algae. Phylogenies inferred from these data revealed specific relationships at the level of genera and species that disagree with those inferred from vegetative cell morphology but agree with those inferred from motile cell characters. The rRNA phylogenies provide even better resolution than that gained from morphology alone. The coccoid lichen alga Trebouxia spp. is specifically related to other coccoid lichen and soil algae (i.e. Myrmecia biatorellae Boye-Petersen and Friedmannia israelensis Chantanachat & Bold), forming the “Lichen Algae Group,” an evolutionarily distinct lineage within the Microthamniales. Trebouxia is a paraphyletic and Pleurastrum a polyphyletic genus in rRNA phylogenies. In contrast to previous hypotheses based on morphology, Pleurastrum terrestre Fritsch & John is not closely related to Trebouxia but occupies an isolated position within the Microthamniales. The filamentous alga Microthamnion kuetzingianum is not ancestral to coccoid members of the Microthamniales but is closely related with the coccoid Fusochloris perforata (Lee & Bold) Floyd, Watanabe & Deason. The Microthamniales are inferred to be an array of independent lineages that radiate nearly simultaneously and may also include some autosporic coccoid taxa previously classified in the Chlorophyceae. Monophyly of the Microthamniales could not be demonstrated unequivocally. In contrast to a hypothesis based on ultrastructure, the Microthamniales are evolutionarily distinct from the Ulotrichales. The latter are ancestral to the radiation of the Microthamniales and the Chlorophyceae in the rRNA phylogenies.

Abstract: Complete nuclear-encoded small-subunit ribosomal RNA (18S rRNA) coding sequences were determined for the coccoid green algae Dictyochloropsis reticulata (Tschermak-Woess) Tschermak-Woess, Myrmecia astigmatica Vinatzer, and M. bisecta Reisigl, to investigate the taxonomic position of Dictyochloropsis Geitler and of the genus Myrmecia Printz. Phylogenies inferred from these data revealed a sister-group relationship between D. reticulata and certain coccoid green algae that lack motile stages (autosporic coccoids) within the order Microthamniales. The monophyletic origin of the Microthamniales, including autosporic coccoids previously classified in the Chlorophyceae, is clearly resolved by the rRNA sequence data. This finding. shows the considerable taxonomic breadth of that order, whose taxonomic position has been unclear so far. A new class, Trebouxiophyceae, is proposed for this group of green algae. Phylogenetic inferences from the rRNA sequences show paraphyly of the genus Myrmecia. The 18S rRNA sequence data suggest that, among taxa that share similar vegetative cell morphologies, the zoospore characters resolve better the actual genus and species boundaries. Within identical zoospore types, the rRNA data allow further resolution of taxonomic relationships. On the basis of the.se findings, I propose that the genus Friedmannia Chantanachat ± Bold be merged into Myrmecia and that only those species be left in the genus Myrmecia that are identical in particular zoospore characters (i.e. those described in detail for M. israeliensis (Chantanachat ± Bold) comb, nov.), namely M. astigmatica, M. biatorellae (Tschermak-Woess ± Ptesst) Petersen, and M. israeliensis. Myrmecia bisecta has to be excluded from Myrmecia; its taxonomic position within the Trebouxiophyceae is unclear.