Single colony genetic analysis of epilithic stream algae of the genus Chamaesiphon spp.
Single colony genetic analysis of epilithic stream algae of the genus Chamaesiphon spp.
. Guntram Christiansen . Andreas Holzinger . 0 1
0 A. Holzinger E. Rott Institute of Botany, University of Innsbruck , Sternwartestraße 15, 6020 Innsbruck , Austria
1 R. Kurmayer (&) G. Christiansen Research Institute for Limnology, University of Innsbruck , Mondseestraße 9, 5310 Mondsee , Austria
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.
Gravel streams; Heteropolar cyanobacteria; Bioindication; Single colony PCR; 16S rDNA gene sequencing
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Guest editors: Eugen Rott, Allan Pentecost & Jan Mares /
Aspects of cyanobacterial biogeography, molecular ecology,
functional ecology and systematics
Introduction
The cyanobacterial morphogenus Chamaesiphon
represents one of the most widespread taxa forming thin
biofilms in mountain rivers worldwide
(e.g., Bu¨rgi
et al., 2003; Rott et al., 2006; Rott, 2008; Sant’Anna
et al., 2011; Scott & Marcarelli, 2012; Gutowski et al.,
2015)
. Several Chamaesiphon species can cover up to
[70% of the wetted perimeter in clear mountain
streams
(Rott & Wehr, 2016)
. The genus
Chamaesiphon was recorded over a broad range of
environmental situations in respect to (i) light (i.e.,
from shaded to highly light (UV) exposed sites), (ii)
pH
(i.e., from acid to alkaline, Cantonati et al., 2007)
and (iii) nutrients
(i.e., from ultra-oligotrophic to
eutrophic conditions, Rott et al., 1999; Rott &
Schneider, 2014)
. Up to date, 33 species of the
morphogenus Chamaesiphon have been validly
described under the rules of the Botanical
Nomenclatoric Code (ICBN, Koma´rek & Anagnostidis, 1999,
and Cyano Database: http://www.cyanodb.cz,
February, 2017). These cyanobacterial species are
distinguished based on morphological characters, and
although some morphological characters are less
stable than others, several of the morphospecies of the
genus Chamaesiphon have been recorded repeatedly
from different regions in the world
(e.g., Koma´rek &
Anagnostidis, 1999; Rott & Wehr, 2016)
.
Microbiological typification defines the morphogenus
Chamaesiphon as a simple unicellular cyanobacterium
with typical asymmetrical binary fission (called
budding or exocyte or exospore formation) produced at
one pole of the mother cell, where typically one single
or a consecutive large series of small exospores (or
small buds) is formed
(Herdman et al., 2001)
.
Colony forming cyanobacteria can reach a
macroscopically visible size from clonal cellular growth.
This facilitates the isolation of single individuals
directly from field samples for analyses of their
genetics, cyanotoxins or other bioactive secondary
metabolites
(e.g., Kurmayer et al., 2002)
. Advanced
molecular techniques have increased the sensitivity of
PCR, resulting in the possibility to amplify DNA
fragments from just picograms of template DNA, such
as from single colonies of cyanobacteria. This makes it
possible to perform dozens of PCR experiments
amplifying large DNA fragments ([1000 bp) from a
single specimen
(e.g. Chen et al., 2016)
. Combining
the field-based techniques with advanced molecular
biological methods holds great potential to analyze the
ecological, as well as phylogenetic, diversification of
cyanobacteria, particularly if they are difficult to
cultivate
(e.g., Maresˇ & Cantonati, 2016)
. In general, a
detailed molecular resolution of Chamaesiphon
morphospecies might allow a better characterization of
running water habitats that are under environmental
stress induced by regional climate change or by
anthropogenic influence (e.g., Loza et al., 2013).
The aim of this study was to characterize
Chamaesiphon morphospecies using molecular biological
techniques on the individual (single colony) scale,
which would allow to relate morphological descriptors
to genotype variability. We speculated that
morphological differentiation might correlate with phylogeny,
even between morphospecies, because of selective
environmental pressure resulting in phylogenetically
distinct ecotypes. For example, high mechanical
pressure in lotic ecosystems may lead to
morphospecies forming a multilayered cell wall and growing in
colonies
(assigned to Chamaesiphon subgenus
Godlewskia, Koma´rek & Kasˇtovsky´ , 2003 (...truncated)