Single colony genetic analysis of epilithic stream algae of the genus Chamaesiphon spp.

Abstract

In order to understand Chamaesiphon spp. evolution and ecological diversification, we investigated the phylogenetic differentiation of three morphospecies from field samples by means of single colony genetics. Individual colonies of three different morphospecies (C. starmachii, C. polonicus, C. geitleri,) were isolated from lotic gravel streams and their 16S rDNA nucleotide variability was analyzed. For a number of individual colonies, microscopical and ultrastructural analysis was also performed. A phylogenetic tree of all major lineages of the phylum of Cyanobacteria assigned all Chamaesiphon genotypes (1149–1176 bp) most closely with the family of Gomontiellaceae of the order Oscillatoriales. The sequences obtained from colonies assigned to C. starmachii (n = 21), C. polonicus (n = 9), and C. geitleri (n = 17) were found to reveal high average (3.5%) nucleotide diversity. No phylogenetic sub-branching in correspondence with morphology was observed suggesting that the three Chamaesiphon morphospecies did not represent monophyletic taxa. We could not attribute specific thylakoid ultrastructure to phylogenetic sub-branches; however, the observed parietally and loosely arranged thylakoids indicate that for the genus Chamaesiphon, the variability in thylakoid ultrastructure might have been underestimated. In summary, the high nucleotide diversity of the 16S rDNA gene implies phylogenetic diversity that corresponds little to morphological classification.

Introduction: Recent developments in cyanobacterial research with special reference to aquatic habitats, molecular ecology and phylogenetic taxonomy

“…The 16S rRNA gene sequencing of the previously morphologically defined genus of planktic cyanobacteria Sphaerocavum have brought evidence for its identity with Microcystis, while detailed analysis of the rRNA ITS data suggested that it was a separate species within this genus. Another study focused on a single genus, Chamaesiphon, where a reproducible protocol for single-colony sequencing of epilithic cyanobacteria in streams was developed (Kurmayer et al, 2017). The SSU rRNA data obtained in that study did not allow any firm conclusions regarding the present species as the morphology and ultrastructure data were not congruent with the reconstructed phylogeny.…”

“…The thematic clusters of contributions in this special section (Supplementary Table 1) comprised the following: (i) problems and developments of the polyphasic evaluation of cyanobacterial biodiversity on the generic and suprageneric levels (Komárek, 2017;Mareš, 2017), and on the infrageneric level (Kurmayer et al, 2017;Rigonato et al, 2017), based on phylogenetic taxonomy; (ii) implementation of the results of modern taxonomic surveys into practical applications such as floristic and environmental research (Davydov & Patova, 2017;Komárek, 2017); (iii) molecular and morphological diversity and adaptation of taxa and/or OTUs to special environments and niches assessed by next-generation sequencing Ruber et al, 2017;Vogt et al, 2017); and (iv) occurrence of specific morphospecies and communities linked to and regulated by specific environmental characteristics in biocalcified lowland streams (Pentecost, 2017), alpine streams (Kurmayer et al, 2017), stratified freshwater lakes (Ruber et al, 2017), and marine tidal flats . The main merits and the taxonomic and biogeographic scope of the individual contributions are summarized in Online Supplemental Table 1.…”

“…However, the results could not be verified by the single-colony environmental sequencing of the SSU rRNA gene due to its high infrageneric variability (Kurmayer et al, 2017), although Chamaesiphon still turned out as a monophyletic genus. Other ecological traits for marine tidal flats included sediment patch analysis based on sandy shore depth profiling.…”

Novel green algal isolates from the Egyptian hyper‐arid desert oases: a polyphasic approach with a description of Pharao desertorum gen. et sp. nov. (Chlorophyceae, Chlorophyta)

“…Polyphasic approaches integrating morphological, ecological, adaptive‐biology, molecular‐phylogeny and bioorganic‐chemistry data are vital not only when dealing with morphology‐poor strains, but also when the reconciliation of morphological and genetic data is difficult or impossible without additional evidence (Kurmayer et al. ).…”

“…It is now accepted that light microscopy has limitations for accurate species recognition and delimitation, especially of morphologically simple coccoid algae, which are common in soils (Fu c ıkov a et al , Leliaert et al 2014, Leliaert and De Clerck 2017. Polyphasic approaches integrating morphological, ecological, adaptive-biology, molecular-phylogeny and bioorganic-chemistry data are vital not only when dealing with morphology-poor strains, but also when the reconciliation of morphological and genetic data is difficult or impossible without additional evidence (Kurmayer et al 2017).…”