Trebouxiophyceae, Chlorophyta - (S)FTP hesla na Botany

2 Aims of the thesis
Aims and outline of the thesis
The general objective of the thesis was to taxonomically revise several genera of the
green aerophytic algae, using both traditional morphological and modern molecular phylogenetic
approaches. For the revision, I chose two coccal genera characterized by the complicated
chloroplast structure (Asterochloris and Dictyochloropsis) and the ubiquitous filamentous
genus Klebsormidium.
In particular, two principal aims can be summarized as follows:
1) To test the stability and suitability of current and newly suggested morphological
discriminating features for the distinction of the particular species
(Papers 1, 2, 4).
2) To revise the species concept of the genera, using the combination of selected
morphological features and molecular markers (Papers 3, 5).
3 Outline of the thesis
The thesis comprehends the taxonomical investigation of three aerophytic green algal
genera – Klebsormidium, Asterochloris and Dictyochloropsis. In Klebsormidium, the species
concept differentiating in morphological view two closely related species was investigated by
the comparison of several morphological characters in 40 isolates. In Asterochloris and Dictyochloropsis,
the combination of detailed morphological study of chloroplast structure and
the molecular phylogenetic analyses was performed to delimit particular species of the genera.
3.1 Species concept in Klebsormidium
The stability and suitability of several morphological characters was tested for the distinction
between two narrowly related species Klebsormidium flaccidum and K. nitens. In
forty isolated strains, the variability in cell dimensions, filament length, character of zoosporangia
and zoospore germination was studied. Moreover, the habit of cell morphology in relation
to the culture age was studied in six randomly chosen strains. In two selected strains, the
effect of physico-chemical parameters (temperature, humidity, illumination and pH) on cell
width was further studied. The study showed variability in taxonomically relevant morphological
features during growing of the species in cultures and impossibility to clearly define
the species by the combination of current morphological markers (Paper 1).
The comparison of ascertained morphological features with the molecular phylogenetic
data was not performed, since the broad phylogenetic study of Klebsormidium is presently in
progress, based on the comparison of rbcL sequences of forty isolated strains (Fabio Rindi,
pers. comm.).
3.2 Taxonomy of Asterochloris
First, the confocal microscopy was utilized to compare the chloroplast morphology and
ontogeny among five strains of the green alga Asterochloris. The examination revealed the
existence of interspecific differences in the chloroplast ontogeny of Asterochloris, based upon
the specific chloroplast structures observed in a single species (Paper 2).
Next, the broad phylogenetic study was performed on the 34 cultured strains, using nuclear-encoded
ITS rDNA and actin intron sequences as the phylogenetic markers. The combination
of molecular phylogenetic analyses and morphological examination resulted in the revision
of the genus. 13 species were newly delimited, including the description of 7 species
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