58th meeting of the czech phycological society 18. - 20. 9...

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58th meeting of the Czech Phycological Society

18. - 20. 9. 2017, University of Ostrava

Abstracts of talks

Prvotní algologický průzkum bývalého vojenského prostoru Brdy

Jan Kaštovský*, Tomáš Hauer, Tomáš Bešta

*University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic

Vojenský prostor Brdy se v roce 2016 otevřel po devadesáti letech veřejnosti laické i odborné.

Prezentovaná studie přináší výsledky prvního systematičtějšího algologického floristického průzkumu

oblasti. Celkem bylo nalezeno na území nové CHKO Brdy více než 800 druhů sinic a řas.

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Taxonomic study of the Zygnema genus

Tereza Šoljaková*, Jan Šťastný

*Charles University, Faculty of Science, Department of Botany, Prague, Czech Republic

The green filamentous conjugating algae (Zygnemataceae) are a cosmopolitan, species-rich group,

often forming a dominant biomass part in freshwater habitats. Despite considerable ecological

importance, the taxonomy of this group is still much confused. Its morphological species concept is

based on characteristics associated with sexual reproduction, such as conjugation type or zygospore

colour and ornamentation. Mainly due to failed conjugation induction under laboratory conditions, this

concept has scarcely been related to modern phylogenetic data so far. This talk focus on current state of

this problematics.

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Crenotia thermalis – recent material from travertines in Slovakia vs. type material

Alica Hindáková1, Jana Kulichová2, Łukasz Peszek3

1Institute of Botany, Plant Science and Biodiversity Centre SAS, Bratislava, Slovakia,

[email protected] 2Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ- 128 01 Prague, Czech

Republic, [email protected] 3Faculty of Biology and Agriculture, Podkarpackie Innovative Research Center of the Environment,

University of Rzeszów, Zelwerowicza 8B, PL- 35-601 Rzeszów, [email protected]

Keywords: diatoms, morphological variability, Slovakia, mineral springs, type materials

Mineral springs rising from constantly forming travertines in Slovakia provide good conditions for the

development of cyanobacteria and algae. One of the most common diatoms are representatives of the

genus Crenotia Wojtal, previously classified into Achnanthes thermalis (Rabenh.) Schoenf. Rich

populations of these species have been observed in boreholes supplied by mineral water in Slovakia,

namely at Gánovce, Močiar, in spring craters at Rojkov and Liptovský Ján, Sivá Brada, as well as in

recent Rivularia-stromatolites at Gánovce. The aim of our study was to illustrate morphological

variability of populations living epilithic in „open“ areas (in boreholes, springs, craters) and

populations living epiphytically in „limited“ area (inside stromatolites, between filaments of Rivularia).

We tried to appoint boundaries between all observed Crenotia populations on the shape of diatom

frustules. For this reason, the type material of Achnanthidium thermale Rabenh., as well Achnanthes

gibberula var. angustior Grunow, A. grimmei Krasske with both var. inflata and var. elliptica, were

involved in our studies. The multivariate analyses should clear the existence of separate species vs.

morphodemes in Crenotia populations, with the help of the available type materials. Additionally to

answer our question, whether new frustule shape observed in field samples should be considered as an

adaptation to living space („Lokalmodifikationen“, morphodemes, ecomorphotypes) or they should be

described as new species, eventually as new varieties according to the old classification.

The study was supported by the grant agency VEGA, No. 2/0060/15.

References:

Lange-Bertalot, H., Krammer, K. (1989): „Achnanthes eine Monographie der Gattung. Mit Definition

der Gattung Cocconeis und Nachträgen zu den Naviculaceae.“ Bibl. Diatom. 18: 1-393.

Wojtal, A.Z. (2013): „Species composition and distribution of diatom assemblages in spring waters

from various geological formations in southern Poland“. Bibl. Diatom. 59: 1-436.

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Genomic insights into the life of algae

Marek Eliáš*

*University of Ostrava, Faculty of Science, Department of Biology and Ecology

Algae are an extremely diverse assemblage of organisms that has been generally much less studied than

animals and plants. Recent years have witnessed the advent of next generation sequencing technologies

and the development of bioinformatics tools that enable us to read and interpret genome (and

transcriptome) sequences from essentially any organism of our interest. Algal research has started to

benefit enormously from this revolutionary change. In my talk I will briefly review examples from the

recent literature and research of my own lab of what can be deduced from genome and transcriptome

sequences about various aspects of algal evolution, molecular biology, physiology, and reproduction.

The talk should persuade everybody that genomics of algae is a fascinating endeavor that will

transform all fields of algal biology.

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Effect of frost and thaw on seasonal dynamics of Arctic strain of Zygnema sp.

(Zygnematophyceae)

Kateřina Trumhová1, A. Holzinger2, G. Neuner3, M. Pichrtová4 1Department of Botany, Charles University, Czech Republic, [email protected]; 2Institute of Botany, University of Innsbruck, Austria, [email protected]; 3Institute of Botany, University of Innsbruck, Austria, [email protected] 4Department of Botany, Charles University, Czech Republic, [email protected]

Zygnematophycean green algae have a wide distribution and can form a dominant part of many hydro-

terrestrial ecosystems, where they are frequently encompassed by environmental stress like high

irradiation, desiccation or low temperatures. Effects of desiccation and UV irradiation have been

studied in strains from the High Arctic. However, knowledge about their ability to cope with freezing

temperatures is missing. Zygnema sp. can produce high amounts of biomass and form characteristic,

extensive mats. It has been confirmed by many field observations, that mats occur only seasonally and

have a temporary character. We tested frost resistance of Zygnema sp. strains of different culture age (2

weeks and 8 months) using programmable freezers that enabled to set various parameters – cooling

rate, warming rate, target temperature and time of exposure. We exposed young cultures to freezing

temperatures down to -14°C, whereas old cultures were frozen down to -70°C. Survival rate of cells

after freezing was tested using fluorescence staining with 0.1% Auramine O dye and measurement of

photosynthetic activity by the steady-state quantum yield of PSII in the light (ФPSII). Young cultures

showed recovery after freezing from -6°C to -8°C, whereas old cultures could survive even freezing

from to –70°C. Cryo-microscopical observations and ultrastructure examination allow us to visualize

the cellular effects of freezing temperatures and frost injury. Our results show that frost hardening via

formation of pre-akinetes is crucial for the survival of harsh temperature conditions prevailing in High

Arctic and plays a key role in seasonal dynamics of this alga.

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Innovations in the thylakoid membrane complexes of chromerid algae: losses, gains, and

divergence

Heather J. Esson, Roman Sobotka, Miroslav Oborník

*Biology Centre CAS, v.v.i., Institute of Parasitology, Laboratory of Evolutionary Protistology, České

Budějovice, Czech Republic

The light dependant reactions of oxygenic photosynthesis are carried out by multi-protein complexes

embedded in the thylakoid membranes of cyanobacteria and plastids: Photosystems I and II (PSI and

PSII), cytochrome b6f, and ATP synthase. While the function of these complexes - the harnessing of

light energy to generate ATP and NADPH - is conserved, their protein subunits vary between

photosynthetic taxa, particularly in PSI and PSII. Some of these variations reflect evolutionary

relationships, especially within the red and green plastid lineages, respectively, in eukaryotes. These

variations can affect binding properties within and between the complexes, which in turn influence the

dynamics of energy transfer and dissipation within the electron transport chain. Chromera velia and

Vitrella brassicaformis (“chromerids”) are photosynthetic relatives of apicomplexan parasites and

possess red-derived plastids of secondary or tertiary endosymbiotic origin; in Chromera,

photosynthesis is extremely efficient and resistant to inhibition under ordinarily stressful light

conditions. We performed in silico and biochemical analyses of thylakoid membrane complexes in

Chromera and Vitrella, concentrating on PSI. Chromera and Vitrella have lost a relatively large

number of genes coding for protein subunits in the photosystems compared to other taxa with red

plastids, but have gained three (Chromera) or one (Vitrella) PSI subunits with no discernible function

or homologs. Moreover, Chromera PSI incorporates two iron superoxide dismutases (FeSODs) as

subunits while Vitrella possesses one, suggesting that the water-water cycle plays an important role in

mitigating the effects of reactive oxygen species resulting from photosynthetic electron transfer in

chromerid plastids. Finally, three of the four PSI-bound light-harvesting complex (LHC) proteins in

Chromera appear unrelated to two of the three LHCs in Vitrella. The two remaining sequences are

closely related and appear to belong to the LI818 group of LHC proteins. Our results indicate that

plastids in Chromera and Vitrella have both evolved similar strategies to mitigate the potentially

deleterious effects of photosynthetic energy transfer.

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A polyphasic approach to the delimitation of diatom species: a case study for the genus

Pinnularia

Jan Kollár*, Pieter Vanormelingen, Aloisie Poulíčková, Eveline Pinseel, Caroline Souffreau, Petr

Dvořák and Wim Vyverman

*Department of Botany, Faculty of Science, Palacký University Olomouc, Czech Republic

Diatoms (Bacillariophyta) are one of the most abundant and arguably the most species-rich group of

algae, with estimates of the total number of extant species ranging between 30,000 and 200,000.

Consequently, diatoms play a crucial role in aquatic ecosystems and are widely used in biomonitoring,

paleoecology and biotechnology. Nevertheless, despite the presence of (pseudo)cryptic diversity,

diatom species taxonomy is still largely based on morphology only and consequently our understanding

of diatom species boundaries and diversity is still rather small. Pinnularia represents one of the most

taxon-rich diatom genera with 730 currently accepted taxa. In this study, we focused on the

delimitation of species in one of the major clades of the genus, the Pinnularia subgibba group, based

on 105 strains. We compared genetic distances between the sequences of seven molecular markers and

used the most variable genes to formulate a primary hypothesis on the limits of species using three

single-locus delimitation methods. Moreover, adopting a polyphasic approach, we compared the

molecular data with morphology and, when available, with other lines of evidence, such as

biogeography, ecology and reproductive compatibility. The results indicate 15 monophyletic species

are present within the group. The vast majority of these are yet unknown to science and/or members of

pseudocryptic species complexes, stressing the urgent need for a systematic revision of this clade or

even diatoms in general.

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Proteome of Euglena gracilis plastid - implications of the secondary endosymbiosis and traces of

its even more colorful history

Anna M. G. Vanclová*, Martin Zoltner, Steven Kelly, Petr Soukal, ThankGod E. Ebenezer, Julius

Lukeš, Vladimír Hampl, Mark C. Field

* Faculty of Science, Charles University in Prague

Euglena gracilis is a representative of phototrophic euglenids harboring secondary plastids acquired

horizontally from green algae. These organisms are very interesting not only from the applied research

point of view, as they are able to synthesize various compounds potentially usable in biotechnology or

pharmacology, but mainly from the basic research and evolutionary perspective. They are members of

Exavata, a supergroup whose study is crucial to understanding the eukaryotic phylogeny as a whole.

Their plastids were established de novo in a previously heterotrophic organism in possibly not so

distant past via secondary endosymbiosis, an event with far-reaching molecular and evolutionary

implications. Moreover, a substantial number of euglenid plastid-associated genes was shown to be

related neither to the plastid ancestor, nor other euglenozoa, which suggests even more complex

evolutionary past of these organisms. E. gracilis is a well-established laboratory model that has been

studied thoroughly regarding its metabolism, physiology and ultrastructure, however, its nuclear

genome has not been sequenced until recently because of various challenges posed by its unusual and

complex organization and relatively great size. As a part of the EuglenaDB genome sequencing project

(https://sites.dundee.ac.uk/euglenadb/), plastid proteins of E. gracilis were identified via liquid

chromatography tandem mass spectrometry and quantified by MaxQuant. Three replicates and three

comparisons against mitochondrial protein fraction were performed to minimize contamination from

other cell fractions and to maximize the credibility of the plastid localization of the predicted proteins.

The set of 1201 putative plastidal proteins was annotated, sorted and used for metabolism

reconstruction, phylogenetic analysis of their evolutionary origin and analysis of plastid-targeting

domains.

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The effect of realistically simulated UV radiation on polar and alpine strains of Zygnema

Martina Pichrtová*, Andreas Albert, Jenny Uhl, Siegfried Aigner, Kateřina Trumhová, Andreas

Holzinger

*Charles University, Department of Botany

Zygnema sp. forms macroscopically visible mats in polar and alpine terrestrial habitats where they are

exposed to environmental stresses. We experimentally exposed three Zygnema sp. strains to elevated,

but realistic UV A and UV A+B irradiation. The effect of UV on photosynthetic activity, morphology,

ultrastructure and metabolome was investigated. The investigated Zygnema sp. strains can cope very

well with elevated UV radiation. The main mechanisms involved in protection are xanthophyll cycle

and production of phenolic compounds.

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qPCR-based detection of a filamentous brown algal endophyte in Saccharina latissima

Miriam Bernard1, Sylvie Rousvoal1, Marion Ballenghien2, Bertrand Jacquemin2, Akira F. Peters3,

Catherine Leblanc1 1Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine

Models, Station Biologique de Roscoff, Roscoff, France 2Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMI 3614, Evolutionary Biology and Ecology

of Algae, Station Biologique de Roscoff, Roscoff, France 3Bezhin Rosko, Santec, France

The marine brown macroalga Saccharina latissima is an important primary producer in temperate to

cold northern hemisphere shores and an economically relevant seaweed with high industrial potential.

Morphological changes - such as dark spots, twisted stipes and deformed blades - have been observed

in wild populations and seaweed farms. The putative cause for the occurring symptoms is the

filamentous endophytic brown alga Laminarionema elsbetiae, which is known to invade stipes and

fronds of its hosts.

We conducted field surveys to measure the prevalence of L. elsbetiae in S. latissima populations and to

understand its ecological impact. Until now, epidemiological studies on kelp endophytes were mainly

based on the examination of microscopic sections, followed by time-consuming isolation and

cultivation steps in order to identify the endophyte. As a novel approach, we developed and validated a

highly specific q-PCR assay for relative quantification of the endophyte L. elsbetiae within its host S.

latissima. We applied the assay to localize and quantify endophytic filaments of L. elsbetiae along S.

latissima sporophytes and showed that these filaments are distributed unequally within the host, with

significantly more endophytes being present in the blade tip than in other parts. Furthermore, an

epidemiological study conducted over one year in Brittany showed that seasonality and environmental

factors have a significant effect on both endophytic prevalence and infection rates, with higher relative

infection rates during summer. Finally, our results obtained from laboratory-raised sporophytes that

were transferred to a seaweed farm suggested that the infection might occur early in the sporophytic

life stage of the kelp. Altogether, these qPCR-based studies allowed us to explore the dynamics of the

endophytic infection during the Saccharina life cycle in field populations of this kelp. In the future this

approach could be applied to study other host-endophyte pairs using specific primers.

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Life cycle of Vitrella brassicaformis: similarities with apicomplexans

Zoltán Füssy*, Miroslav Oborník



Environmental sequencing revealed that core apicomplexans are nested within lineages with a diversity

of trophic strategies, including parasitic, predatory, and phototrophic. We investigated life cycle of

algal relative of apicomplexans, Vitrella brassicaformis. We have identified isogametic sexual behavior

in V. brassicaformis, exhibiting a fusion of two motile cells. Notably, no apical structure, typical for

motile stages in other apicomplexans and related organisms, was found in zoospores of V.

brassicaformis. Genetic repertoire of the species reflects these differences. Vitrella encodes core

meiotic factors but lacks genes for apical complex components, such as RING2 and Myosin H. We also

identified a possibly ancestral diversity of protein kinases and cyclins, that may play role in life cycle

decisions in V. brassicaformis. Based on life cycle complexity in apicomplexans and their sister

groups, we suppose that their common ancestor had a complex life cycle and cell biology. Some of the

extant species, however, underwent a reduction of their cellular complexity possibly to better suit their

ecological needs. These results may indicate that an ancestrally rich battery of biological processes

could have enabled apicomplexans to establish complicated parasite-host interactions.

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Snow algae of Balkan mountain ranges

Jaromír Lukavský, Vladislav Cepák, Linda Nedbalová, Ivan Iliev, Jana Kvíderová*

*Centre for Polar Ecology, University of South Bohemia

For the first time, the main Balkan mountain ranges (Vitosha, Pirin, Stara Planina, Rhodope and

Olympus) were screened systematically for occurrence of snow algae. The samplings were performed

in late spring in 2005 – 2017 at elevations above 1500 and below 3000 m a.s.l. The cysts of green

algae Chlamydomonas cf. nivalis, Chloromonas nivalis, Chloromonas brevispina and Chloromonas

rostafiński were found in majority of samples. The elevation effects on taxa distribution were found

statistically significant for Olympus Mt., but not for Pirin, Stara Planina and Rhodope.

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The autofluorescence of lipophilic organelles in the eustigmatophyte – Vischeria sp.

Jana Pilátová*, Kateřina Schwarzerová, Peter Mojzeš, Kamila Hurková

*Charles University, Faculty of Science, Department of Plant Biology

The research interest in the eustigmatophyte algae rapidly grew in the last decade because of their great

biotechnological potential, and more and more questions have recently emerged for the basic research,

too. Eustigmatophyte algae are evolutionary very old group of Stramenopiles, which were defined as a

separate class on account of the presence of very specific lipophilic organelles. These include the

extraplastidial stigma in zoospores and the reddish globule commonly occurring in vegetative cells,

which has been well documented by light and electron microscopy in last fifty years. However, the

composition, biogenesis and physiological functions of these organelles are not known yet. The cells

contain also lipid bodies consisting of polyunsaturated fatty acids (PUFA) contributing up to 50 % of

the biomass dry weight, which is particularly valuable for biotechnologies. Surprisingly, the lipophilic

organelles (e.g. lipid bodies and reddish globule) are autofluorescent in eustigmatophytes, but the

actual origin and more detailed properties of their autofluorescence have not been well described till

now. In our study we want to contribute to the revelation of the fluorecent nature of the lipophilic

organelles by means of fluorimetry, confocal Raman microscopy and mass spectrometry analysis of the

fraction of lipophilic organelles, mainly the lipid bodies and reddish globule in our model species

Vischeria sp. BOF79.

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Molecular evolution and taxonomy of freshwater and terrestrial Ulvophyceae

Pavel Škaloud*, Fabio Rindi, Christian Boedeker, Frederik Leliaert, Michala Klimešová, Veronica

Malavasi, Alena Lukešová

*Charles University, Faculty of Science

Freshwater ulvophycean algae display a wide variety of thallus morphologies, ranging from

microscopic unicellular organisms to larger, filamentous or parenchymatic algae. Species are also

found in a wide diversity of habitats, ranging from brackish to freshwater, semi-terrestrial and aero-

terrestrial habitats. The current knowledge on the evolution and taxonomic position of freshwater

ulvophytes is however severely limited. We performed the molecular and morphological investigation

of more than 60 ulvophycean strains deposited in the 11 algal culture collections worldwide, including

a number of authentic strains. Based on our new findings, and incorporating the latest knowledge on

the molecular phylogeny, ultrastructure and morphology of the species, we significantly revised the

taxonomy of ulvophytes, in particular the orders Ulvales and Ulotrichales. We propose to resurrect one

order and family (Chlorocystidales and Chlorocystidaceae), and describe six new families and one new

genus. In addition, we formally describe the order Ignatiales and family Ignatiaceae based on published

molecular and ultrastructural data. The majority of presented data will be published in the upcoming

volume of the Freshwater Flora of Central Europe, Vol 13: Chlorophyta: Ulvophyceae (Süßwasserflora

von Mitteleuropa, Bd. 13: Chlorophyta: Ulvophyceae).

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Mannitol accumulation as an osmotic adjustment mechanism in the apicomplexan cousin

Chromera velia

Aleš Tomčala*, Ivana Schneedorferová, Aleš Tomčala, Kateřina Kabeláčová, Iva Opekarová, Veronika

Kyselová, Miroslav Oborník



Apicomplexan is a group of parasites causing severe deadly diseases of human and livestock.

Chromera velia represents a member of apicomplexan sister group chrompodellids possessing

photosynthesis. The extraordinary phylogenetic position of this brownish alga together with fast and

easy cultivation make C. velia an excellent model for studying evolutionary shift of live strategy from

phototropism to parasitism. Furthermore study of C. velia basic biochemical pathways could provide us

very important information about apicomplexans themselves and helps to find another target processes

for anti-apicomplexan drugs. The aim of this study was to investigate the reaction of C. velia to

osmolarity stress. The data covers monosaccharide, amino acid, intermediates of basal metabolism,

chlorophyll, pigments, pheophytin, and lipid analysis. C. velia cultures were treated with seven levels

of salt concentrations reaching from 0.3 g/l to 66g/l of artificial marine salt. The growing curves show

that C. velia grows similarly from 16 to 50g/l. Mannitol was detected as the most abundant

monosaccharide with positive correlation to salinity. Significant differences among the experimental

groups were recorded in the level of amino acid and intermediates and also intact lipids. However, no

of these compound seems to have any relationship to osmotic adjustment itself.

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Chlainomonas sp. (Chlorophyceae), an alga causing red snow on ice-covered lakes:

ecophysiological and morphological comparison of two populations (High Tatras vs. Austrian

Alps)

Lenka Procházková*, Daniel Remias, Andreas Holzinger, Tomáš Řezanka, Linda Nedbalová

*Charles University, Faculty of Science, Department of Ecology

Based on multiple molecular markers analysis (18S rDNA, ITS1, ITS2 rDNA, rbcL), a specialized

microalga causing red snow on the melting ice cover of an alpine lake in the High Tatras, Slovakia, was

shown to be identical with Chlainomonas sp. thriving in a similar habitat in the Austrian Alps. The

population mostly consisted of quadriflagellate cells. Ecophysiological and morphological differences

between both locations (e.g. lower saturation irradiance, higher α-tocopherol and 13Z-isomer

astaxanthin content, slightly lower PUFAs and higher overall astaxanthin level, larger cell sizes, higher

population density in the High Tatras) illustrated well the influence of habitat harshness on physiology,

the prolonged time for cell maturation and population development during the summer season on snow

algae. Finally, Chlamydomonas nivalis, alga causing ´conventional´ red snow was included into this

physiologic-ecological comparison

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Fatty acid biosynthesis in chromerid algae

Miroslav Oborník*, Aleš Tomčala, Jan Michálek



The two coral-associated phototrophic alveolates, Chromera velia and Vitrella brassicaformis (also

called chromerids), have been shown to be closely related to apicomplexan parasites. Availability of

chromerid nuclear and organellar genome sequences together with their easy and rapid cultivation

makes chromerids suitable models to study metabolic changes caused by an evolutionary transition

from phototrophic ancestor to apicomplexan parasite. We explored the de novo fatty acid biosynthesis

in chromerids and compared it to the architecture of fatty acid metabolism of apicomplexan parasites

by means of analytical biochemistry and molecular phylogeny. Based on our data, we reconstructed the

fatty acid biosynthetic pathway in chromerid algae: the plastid localized FAS II pathway is responsible

for de novo fatty acid biosynthesis reaching the maximum length of 18 carbon units. Our model

proposes that fatty acids are then transported into the cytosol and endoplasmic reticulum to undergo the

subsequent structural modifications made by elongases and desaturases. Also multimodular enzymes of

FAS I/PKS reaching over 11,000 amino acids organized in 2 to 5 multi-domain modules were

identified in the chromerid genomes, however, the absence of acyl transferase domain in some modules

suggests their use more likely in the polyketide synthesis than in the synthesis of fatty acids. On the

other side, two genes for acetyl-CoA carboxylases were identified in chromerids with plastid and

cytosolic localizations, respectively, suggesting the presence of functional fatty acids biosynthesis in

both plastid and cytosol.

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Candidatus Phycorickettsia trachydisci, a novel lineage of Rickettsiaceae engaged in a long-term

partnership with eustigmatophyte algae

Tatiana Yurchenko*, Tereza Ševčíková, Pavel Přibyl, Khalid El Karkouri, Vladimír Klimeš, Raquel

Amaral, Veronika Zbránková, Eunsoo Kim, Didier Raoult, Lilia M. A. Santos, Marek Eliáš


Rickettsiales are obligate intracellular bacteria originally found in metazoans, but more recently

recognized as widespread endosymbionts of various protists. One rickettsial genus was detected also in

several green algae, but reports on rickettsial endosymbionts in other algal groups are lacking. Here we

show that several distantly related eustigmatophytes (coccoid algae belonging to Ochrophyta,

Stramenopiles) are infected by Candidatus Phycorickettsia trachydisci gen. et sp. nov., a new member

of the family Rickettsiaceae. Sequencing the Phycorickettsia genome from Trachydiscus minutus

CCALA 838 revealed genomic features (size, GC content, number of genes) typical for other

Rickettsiales, but some unusual aspects of the gene content were noted. Specifically, Phycorickettsia

unusually lacks genes for several components of the respiration chain, haem biosynthesis pathway, or

c-di-GMP-based signalling. On the other hand, it uniquely harbours a six-gene operon of enigmatic

function that we recently reported from various bacteria and plastid genomes of two distantly related

eustigmatophytes. Strikingly, the eustigmatophyte operon is closely related to the one from

Phycorickettsia, suggesting a gene transfer event between the endosymbiont and host lineages in early

eustigmatophyte evolution. We hypothesize an important role of the operon in the physiology of

Phycorickettsia infection and a long-term eustigmatophyte-Phycorickettsia coexistence.

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13

Freezing tolerance of pennate diatoms: polar vs. temperate strains

Eva Hejduková*

*Charles University, Faculty of Science, Department of Ecology

Polar environment is characterized by many extremes. Low temperatures, lack of liquid water, irregular

nutrient and light supply, fluctuations in daily and annual cycles seem unfavourable for life. In spite of

this, diatoms (Bacillariophyceae) are one of groups that adapted well and dominate in many polar

habitats. Generally, microorganisms overcome unfriendly conditions via dormancy, but no

morphologically different resting stages are known in freshwater diatoms.

In this study, the tolerance of polar and temperate diatoms to freezing was experimentally tested and

the difference in survivability of vegetative and resting cells was assessed. Diatom strains for the

experiments were isolated in 2014 using natural samples from Maritime Antarctica (James Ross Island,

Vega Island) and Arctic (Svalbard). Further strains were acquired from culture collections of

microorganisms (CCCryo and BCCM). Resting cells were induced by incubation under nitrogen and

light limitation in low temperature. The vegetative and resting cells of 26 strains were exposed to

different freezing treatments to –4 °C, –20 °C, –40 °C and –180 °C. Treatments differed also in the rate

of freezing and thawing (continuous versus abrupt).

The study concludes that the diatom strains are sensitive to freezing. The freezing temperature had a

significant effect on survival, but the results did not prove significant difference in survival between

polar and temperate strains of diatoms, neither the importance of resting cells for the survival of

freezing treatments. However, in the –20 °C treatment, polar strains showed higher viability in

comparison with temperate ones suggesting that they are better adapted to the temperature that is

habitual in their natural environment. Overall, the strains of Pinnularia borealis species complex

revealed to be extremely resistant and survived even the liquid nitrogen treatment (–180 °C).

This is the first study about diatom freezing tolerance comparing strains from polar and temperate

habitats. Even though the conditions of the experiments were artificial, the study brought valuable data

that could be useful for the introduction of diatom cryopreservation in culture collections. How do

polar diatoms cope with their natural environment still remains an open question, which could be

answered by a detailed field studies including multiple sampling throughout the year.

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14

Peculiar plastid genomes of non-photosynthetic green algae

Tomáš Pánek*, Kristína Záhonová, Naoji Yubuki, Eliška Zadrobílková, Vladimir Klimeš, Ivan

Čepička, Marek Eliáš


The loss of photosynthesis is frequently associated with the reduction of size and gene content of the

plastid genome. In exceptional circumstances (e.g. Rafflesia, Polytomella), it can even result in the

complete loss of the plastid DNA. Closely related to Polytomella (Chlorophyta: Chlamydomonadales)

is the diphyletic genus Polytoma, whose members lost photosynthesis independently on Polytomella

and at least Polytoma uvella possesses a huge plastid genome (230 kbp) encoding 29 protein-coding

genes. Here, we present the discovery of a new non-photosynthetic lineage of chlamydomonadalean

algae with a bloated plastid genome. Similarly to Polytoma uvella, its plDNA is repeat-rich and

expanded in intergenic regions. In contrast to P. uvella, it possesses more complex repertoire of plastid

genes since it encodes at least 34 protein-coding genes including subunits of ATP synthase. Our

findings support the hypothesis that Tat-related role for ATP synthase was a key constraint during

parallel loss of photosynthesis in multiple independent lineages of algae and plants.

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Metabolomic approach to shed light on the metabolic pathways that regulate the growth and

morphogenesis of Ulva mutabilis

Gianmaria Califano*, Michiel Kwantes, Thomas Wichard

*Friedrich Schiller University Jena

The green macroalga Ulva mutabilis Føyn interacts mutualistically with microbial flora that influences

growth, development and morphogenesis. Together with 2 bacterial strains, Roseovarius sp. MS2 and

Maribacter sp. MS6, the algae forms a tripartite community under laboratories conditions. The role of

MS6 is to induce the formation of a normal cell wall and the differentiation of the rhizoid tissue. From

the same laboratory, previous researchers isolated an active small molecule from the growing medium

of MS6 in laboratory conditions and in large scale aquaculture, that can reconstitutes alone MS6 effects

on the gametes of Ulva. To investigate the molecular processes underlying the effects of MS6 in Ulva

we have chosen the untargeted metabolomic approach. Therefore, circa 7 million axenic Ulva gametes

were exposed, in triplicates, to the compound and to control conditions for 24 and 48 hours under

standard Ulva growing conditions. Metabolites were extracted with an in-house protocol and analyzed

using gas-chromatography coupled to high resolution mass spectrometer-orbitrap. 258 compounds

were detected, multivariate and univariate statistical analysis did not show significant differences

between the two treatments, however, two compounds showed significant differences in abundances

between the 2 time points (24 and 48 h). Those two biomarkers belong to the classes of sugars and fatty

acids. Furthermore, in order to investigate for changes that were still only occurring at genetic level, in

parallel, an RNAseq experiment is running using another aliquot of the same samples analyzed for

metabolomics. The integration of the two omics techniques is a very promising approach that will shed

light on metabolic pathways that are regulated during morphogenesis of Ulva mutabilis.

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15

Defence reactions of brown algae against the oomycete pathogens Eurychasma and Anisolpidium

Claire M.M. Gachon*, D.G. Müller, M. Strittmatter, P. Murúa, F.C. Küpper, A. Tsririgoti, C. Katsaros,

M. Beckmann, S. Wawra, P. van West, A. Zambounis

*Scottish Association for Marine Science, UK

The fundamental role of microbes in the physiology, development, ecology and evolution of algae is

now well established, yet the detailed mechanisms of these interactions often remain to be elucidated.

The oomycetes Eurychasma dicksonii and Anisolpidium ectocarpii are two obligate intracellular

pathogens with a broad host range that we are using to investigate the immune responses of brown

algae. We find that resistance to infection by Eu. dicksonii is mediated by the hypersensitive death of

the algal cells attacked. This response is accompanied by the deposition of beta-1, 3-glucan in the cell

wall and of blue-fluorescent metabolites, the production of reactive oxygen species, and the induction

of markers usually associated with programmed cell death, such as DNA fragmentation and

metacaspase expression. This hypersensitive response was observed in ten algal species belonging to

four different orders, demonstrating its broad conservation among brown algae (Phaeophyta).

Furthermore, TEM and in vivo staining assays suggest that the induction of algal autophagy might be

another line of defence against A. ectocarpii and possibly, Eu. dicksonii.

In order to identify candidates potentially involved in algal defence, we mined the genome of the

brown alga Ectocarpus siliculosus for homologues of animal and plant defence genes. Whilst

homologues of plant resistance genes are absent from the genome, two families of candidate pathogen

receptors (LRR-ROCO and NB-ARC-TPR proteins) apparently evolve new ligand-binding specificities

by a highly original, controlled, and dynamic exon shuffling mechanism. Hypervariable solvent-

exposed aminoacid residues are subject to positive selection, an unusual feature reflecting strong

evolutionary pressures, such as the ones imposed by a host-pathogen arms race. The genomic

organization, structural and evolutionary features of these candidate pathogen receptors are strikingly

similar to the pathogen recognition systems described in plants and animals.

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16

Phylogeny and evolution of a new parasitic lineage closely related to Apicomplexa

Martin Kolisko1, Elisabeth Hehenberger2, Mark A Freeman3, Arni Kristmundsson4, Patrick J Keeling2 1Institute of Parasitology, Biology Centre CAS, České Budějovice, Czech Republic 2Department of Botany, University of British Columbia, Vancouver, Canada 3Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis 4Institute for Experimental Pathology at Keldur, University of Iceland, Reykjavík, Iceland

The Apicomplexa form a group of obligatory intracellular parasites that cause some of the most

debilitating diseases of humans (for example, the malaria parasite Plasmodium). As such, they possess

several unique adaptations to their parasitic lifestyle, for example the apical complex, which gave the

Apicomplexa their name and is involved in invasion of the host. Moreover, they possess a highly

reduced non-photosynthetic plastid called the apicoplast, which has lost many of its functions, but still

contains a small plastid genome. Although reduced, the apicoplast is an essential organelle as it harbors

pathways for heme, isoprenoid, fatty acid and iron-sulfur cluster synthesis. Relatively recently,

several new free-living lineages, collectively called chrompodellids, were discovered and were shown

to be closely related to the Apicomplexa. The best studied of these new lineages are two photosynthetic

algae called Chromera velia and Vitrella brassicaformis whose genomes were recently fully

sequenced.

Piridium sociabile is a poorly studied parasite of a marine gastropod (Buccinum undatum) that was

originally described in 1936 and classified as an apicomplexan parasite. Here, we present

transcriptomic and genomic data from Piridium sociabile and show that it is actually a sister lineage to

the photosynthetic chrompodellid Vitrella brassicaformis. It therefore represents a lineage that is

closely related to Apicomplexa but acquired a parasitic lifestyle and lost photosynthesis independently.

The complete sequence of the Piridium plastid genome is similar in size to apicoplast genomes and also

has a very similar gene content. We have used our genomic and transcriptomic data to explore and

contrast the evolution of non-photosynthetic plastids and the evolution of parasitism between Piridium

and Apicomplexa.

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Photosynthetic activity of Vaucheria sp. from Svalbard intertidal zone

Jana Kvíderová*, Josef Elster

*Centre for Polar Ecology, University of South Bohemia

The mats of Vaucheria sp. in the intertidal zone represent important factor for stabilization and further

colonization of the sea coast in Svalbard. In last two years, we measured the photosynthetic activity of

Vaucheria sp. in two types of microcosmos as well in situ using variable chlorophyll fluorescence and

gasometry approaches. The preliminary data will be presented.

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17

The enigmatic ROCO protein family: putative immune proteins in algae

David Žihala*, Marek Eliáš


The ROCO family is a group of proteins defined by the presence of a central core consisting of a type

of the GTPase domain (Roc; Ras of complex proteins) and a family-specific novel domain (COR; C-

terminal of Roc). These proteins began to be intensively studied after the discovery that a mutant form

of the human ROCO protein LRRR2 is associated with the onset of Parkinson's disease. Another

direction of thinking about the cellular function of ROCO proteins came with an analysis of the ROCO

gene family in the brown alga Ectocarpus sp. published in 2012. Based on some unique structural

features and the evolutionary pattern of the family it was suggested that ROCO proteins may serves as

immune receptors it the brown alga. We will present the results of our in silico analyses of ROCO

genes from other algae and protists in general, suggesting that immunity-related role may be a more

general feature of the ROCO family.

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Algae and bryophytes of the most extreme lake in Czechia

Dovilė Barcytė*, Linda Nedbalová

*Charles University, Faculty of Science & National Museum

Acid freshwaters exhibit challenging conditions to most life forms and no higher organisms can thrive

there. Extreme example of acid lakes are mining lakes which originated in abandoned metal or coal

mines. Hromnice Lake, situated in the western part of Czechia and formed as a consequence of the

mining of pyritic shales, is the most acidic lake in the country with water pH ~ 2.6 and water chemistry

mainly dominated by sulphate (SO42–), iron (Fe) and aluminum (Al).

The aim of our study was to identify the phytoplankton species of Hromnice Lake using morphological

traits and molecular phylogenetics. The small green coccoid alga was identified as Coccomyxa

elongata, for the flagellate Chlamydomonas-like alga a new genus Acidomandum with a new species

combination A. acidophilum was proposed whereas a prominent euglenophyte was determined as

Euglena mutabilis. In addition, green filaments sampled from the bottom surface close to the shore

were identified as an initial stage (protonema) of the moss. We have sequenced these filaments along

with the adult mosses from the shore and found out that their closest relatives are acid-tolerant

bryophytes. In conclusion, the peculiar environment of Hromnice Lake accommodates unique

organisms.

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18

Size, shape, and growth: allometric scaling and phenotypic diversification within Micrasterias

Helena Bestová*, Cyrille Violle, Thomas Lenormand

*Charles University, Faculty of Science, Department of Botany

The relationship between body size and growth has been long studied. While there is some consensus

on the existence of ‘universal’ scaling laws in multicellular organisms, this is still under debate in

unicellular ones. In particular, while growth varies monotonically with size with a scaling exponent of -

1/4 across multicellular species as predicted by the Metabolic Scaling Theory (MST), a unimodal

relationship between grown and size was observed in unicellular species. This could be caused by

changing constraints along evolutionary transitions or body size. We investigated scaling relationships

in green algae within the Micrasterias genus, characterized by large cells and peculiar fractal-like

morphologies. We asked whether this genus follows MST predictions and how the observed scaling

relationships are regulated by the fractal-like shape of the cells. We experimentally measured

population growth rate, volume, surface, cell size, mass and shape of 24 Micrasterias species.

Our results showed that Micrasterias species follow MST predictions, i.e. express similar allometric

scaling relationships of growth rate as those of multicellular organisms. Interestingly the tremendous

variation in cell shape (fractality, flattening) did not influence scaling relationship. Yet fractal

branching leads to the scaling of the surface to volume higher Euclidean 2/3. We also found a nonlinear

increase in mass with volume, stressing the importance of cell content dilution as one way to cope with

increasing size.

Changes in body plan together with a size-dependent change in density represent efficient mechanism

how to rise scaling of the surface to body mass and overcome external diffusions constraints, which

limits nutrient and CO2 uptake. However further increase in size would be limited by internal diffusion

constraints and therefore requires other major inventions. Overall the Micrasterias genus and its large

morphological diversity represent a panel of optimized phenotypes in terms of metabolism, with

various combinations of allometric strategies that enable it to gain growth rates as predicted by MST.

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19

Uninvited guests: effect of bacteria on growth and mating of the benthic diatom Seminavis

robusta

Emilio Cirri*, Georg Pohnert

*Friedrich Schiller University Jena

Diatoms are important microalgae that shape biofilm communities. Signal molecules mediate their life

cycle and mating, but only recently the first diatom pheromone was identified in the benthic diatom

Seminavis robusta. The proline derived diketopiperazine (diproline) drives the chemoattraction of the

mating partners [1]. Since such a pheromone based communication is a potential target for competing

or pathogenic organisms, we asked if such co-occurring species might interfere with the diatoms´

chemical communication. We studied the pheromone chemistry and behavioral response of S. robusta

both in presence and absence of bacteria. Bioassays with different naturally co-occurring bacterial

strains, quantitative target analysis to check the production and degradation of diproline, and an

untargeted metabolomics approach were used to comprehensively characterize the interaction. We

found that different bacteria have different effects on the mating and the growth of S. robusta, as well

as on the prevalence of diproline, which is always higher in axenic conditions. Comparative untargeted

metabolomics allowed us to survey the diatom chemistry, where amino acids and fatty acids were

regulated in presence of bacteria, suggesting that these could serve bacteria as nutrients.

[1] Gillard et al., Angewandte Chemie International Edition, 2013

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20

Abstracts of posters:

Diversity of the Micrasterias papillifera/ M. radiosa species complex

Kateřina Trumhová*, Jan Šťastný

*Department of Botany, Charles University

We investigated diversity within the Micrasterias papillifera/ M. radiosa (Desmidiales) species

complex. Both species are inhabitants of endangered biotopes, like peat-bogs and, like other desmids,

are used for biomonitoring. Many described varieties for both of them can be found in taxonomic

literature, but their morphological descriptions are overlapping and revision of this species complex

seemed to be necessary. All strains were isolated from peat-bogs and lakes across Europe and dataset

was properly completed by strains from algal collections. Results of phylogenetic analysis of sequences

for ITS and psaA showed, that the real intraspecific diversity of Micrasterias papillifera Brébisson ex

Ralfs was overestimated. Although we could find a little intraspecific diversity within the ‚papillifera‘

lineage in the phylogenetic tree based on ITS sequences, it did not correspond with a morphology of

isolates. M. papillifera possess unexpected morphological plasticity and also some isolates designated

as Micrasterias radiosa Ralfs were present in this lineage. On the contrary, there were only a few

isolates in the lineage ‚radiosa‘. This species seems to be relatively rare and probably has limited

distribution in North Europe and on British Isles. Both species are morphologically well delimited from

each other on the basis of several characters, like a cell size and position of spines on cell wall and can

be relatively simply determined.

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Endocynelles in some algae

Jaromír Lukavský*, V.Cepák, V.Procházka, V. Šenkyplová

*Institute of Botany CAS, v.v.i & Institute of Microbiology CAS, v.v.i.

We have studied endocyanelles in algae Glaucocystis nostochinearum and Gloeochaete witrockiana

and compared their DAPI structures with previous study of Paulinella chromatophora from

Rhizopoda.

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21

Three ecologically diversified green algal genera established symbiosis with a single lichenized

fungus

Lucie Vančurová, Ondřej Peksa, Pavel Škaloud*

*Charles University in Prague, Faculty of Science, Department of Botany, Czech Republic

Symbiosis plays a fundamental role in nature. Lichens are among the well-known symbiotic organisms

distributed worldwide whose ecology is shaped by the requirements of all symbionts forming the

holobiont. The widespread lichen genus Stereocaulon provides a suitable model to study the ecology of

microscopic green algal symbionts (i.e., phycobionts). In this study, we aimed to find a connection

between the phycobiont diversity in Stereocaulon lichens and environmental conditions. We uncovered

the exceptional diversity of phycobionts associated with Stereocaulon. The three identified genera of

phycobionts, Asterochloris, Chloroidium, and Vulcanochloris, are clearly ecologically diversified.

Asterochloris prefers cold, humid climates, Vulcanochloris tolerates warm, extremely dry conditions,

and Chloroidium tolerates a wide range of humidity levels but prefers moderate-to-warm temperatures.

Furthermore, Chloroidium appears to tolerate toxic substances (e.g., heavy metals), as it occurs in

anthropogenic and volcanic habitats. Climate and habitat types shape the distribution of the

phycobionts as well as the distribution of their lichen hosts, which explains the biggest proportion of

variability. The ability to employ ecologically diversified phycobionts correlates with the diverse

environmental conditions in which Stereocaulon lichens grow. It appears that the presence of such a

wide range of phycobionts enables these lichens to extend their ecological amplitude. Moreover, the

low specificity and the ability to switch phycobionts appear to be key factors that enable pioneer

lichens to establish their thalli at new niches.

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22

In situ identification and laboratory studies on the interactions between filamentous brown algal

endophytes and kelps

Miriam Bernard1, Laurence Dartevelle1, Martina Strittmater2, Akira F. Peters3, Catherine Leblanc1 1Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine

Models, Station Biologique de Roscoff, Roscoff, France 2The Scottish Association for Marine Sciences, Oban, UK 3Bezhin Rosko, Santec, France

In the marine environment, small endophytic filamentous algae are known to invade stipes and fronds

of kelps, however few is known about the molecular bases of this interaction and their physiological

impacts. In this context, we investigated the molecular diversity and host specificity of endophytic

brown algae in wild kelp populations by sequencing the COI and ITS1 regions of more than 50

endophytic samples isolated from 5 different kelp species. The endophyte Laminarionema elsbetiae

was isolated from Saccharina latissima and S. japonica tissues. In addition, we identified 3 species of

the genus Laminariocolax, one of which is L. aecidioides, an endophyte with a worldwide distribution

and a broad range of hosts. The other two identified species - L. tomentosoides and a so far undescribed

species of Laminariocolax - were associated to different kelp species of the North Atlantic sampling

sites. Our results suggest that specific host-endophyte patterns exist, as found in kelps from Brittany,

but are variable upon location as observed for other regions like Western Scotland and Helgoland.

To get further insight into the physiology of host-endophyte specific interactions, we set-up an

experimental design focused on the endophyte L. elsbetiae with its main host S. latissima and the

occasional host Laminaria digitata. A co-cultivation bioassay was developed to monitor the impact of

the endophyte on growth of laboratory-grown kelp sporophytes. Whereas no effect was monitored on S.

latissima plantlets, growth of the occasional host L. digitata was significantly decreased within less

than a week when co-cultured with L. elsbetiae. Preliminary results on the prevalence of endophytic

filaments in the kelp tissue suggest that defence reactions against L. elsbetiae were triggered in L.

digitata, but not in S. latissima. Further analyses of endophyte-induced responses in kelps will help to

decipher host specificity and to better understand the bases this interaction.

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23

Evolution of colorless plastids in free-living algae: a project overview

Kacper Maciszewski*, Anna Karnkowska

*Department of Molecular Phylogenetics and Evolution, Faculty of Biology and Biological and

Chemical Research Centre, University of Warsaw, Poland

Secondary non-photosynthetic strains have been discovered in multiple lineages of unicellular algae.

However, the research on mechanisms of loss of photosynthetic function of their plastids has been

focused predominantly on parasitic species belonging to Apicomplexa clade (e.g. Plasmodium and

Toxoplasma genus). In my PhD project, scheduled to begin in October 2017, I am planning to

investigate the loss of photosynthetic function and evolution of non-photosynthetic members of two

clades of free-living algae with secondary plastids: Euglenophyta (Excavata), with green-alga

originated plastids and Dictyochophyceae (Stramenopila) with the plastid of red algal origin. In each of

those clades, photosynthesis has been lost several times independently.

The fundamental data for this project will be obtained by plastid genomes sequencing and

transcriptomes sequencing. Comparative analysis of plastid genomes will enable to identify the loss of

plastid-encoded genes, both related and non-related to photosynthetic processes. Transcriptomes will

be annotated, and plastid-targeted proteins will be reconstructed. The obtained information will enable

assessment of the viability of canonical metabolic pathways in the investigated colorless plastids.

The expected results comprise a comparison between trends of gene loss in the investigated two non-

related lineages’ leucoplasts (non-photosynthetic plastids) as well as between these two clades and

others examined so far, such as non-photosynthetic apicomplexans and diatoms. The work’s primary

objective is to evaluate the patterns of loss and retention of the plastid-encoded genes and metabolic

pathways localized in plastids.

This work is supported by grant 2016/21/D/NZ8/01288 from National Science Centre.

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24

Contrasting patterns in the evolution of the Rab GTPase family in Archaeplastida

Romana Petrželková*, Marek Eliáš


Rab GTPases are a vast group of proteins serving a role of master regulators in membrane trafficking in

eukaryotes. Previous studies delineated some 23 Rab and Rab-like paralogs ancestral for eukaryotes

and mapped their current phylogenetic distribution, but the analyses relied on a limited sampling of the

eukaryotic diversity. Taking advantage of the recent growth of genome and transcriptome resources for

phylogenetically diverse plants and algae, we reanalyzed the evolution of the Rab family in eukaryotes

with the primary plastid, collectively constituting the presumably monophyletic supergroup

Archaeplastida. Our most important novel findings are as follows: (i) the ancestral set of Rabs in

Archaeplastida included not only the paralogs Rab1, Rab2, Rab5, Rab6, Rab7, Rab8, Rab11, Rab18,

Rab23, Rab24, Rab28, IFT27, and RTW (=Rabl2), as suggested previously, but also Rab14 and Rab34,

because Rab14 exists in glaucophytes and Rab34 is present in glaucophytes and some green algae; (ii)

except in embryophytes, Rab gene duplications have been rare in Archaeplastida. Most notable is the

independent emergence of divergent, possibly functionally novel, in-paralogs of Rab1 and Rab11 in

several archaeplastidial lineages; (iii) recurrent gene losses have been a significant factor shaping Rab

gene complements in archaeplastidial species; for example, the Rab21 paralog was lost at least six

times independently within Archaeplastida, once in the lineage leading to the “core” eudicots; (iv)

while the glaucophyte Cyanophora paradoxa has retained the highest number of ancestral Rab paralogs

among all archaeplastidial species studied so far, rhodophytes underwent an extreme reduction of the

Rab gene set along their stem lineage, resulting in only six paralogs (Rab1, Rab2, Rab6, Rab7, Rab11,

and Rab18) present in modern red algae. Especially notable is the absence of Rab5, a virtually

universal paralog essential for the endocytic pathway, suggesting that endocytosis has been highly

reduced or rewired in rhodophytes.

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25

Ecophysiologic and taxonomic reevaluation of three Chloromonas spp. living in snow:

cosmopolitan species turn out to be local ones

Lenka Procházková1, D. Remias2, L. Nedbalová1 1Charles University, Faculty of Science, Department of Biology and Ecology, Prague, Czech Republic 2University of Applied Sciences Upper Austria, Austria

Melting snow fields in alpine and polar regions are inhabited by snow algae, causing discolouration of

snow. In most cases these algae belong to the genera Chloromonas, Chlamydomonas and

Chlainomonas. Snow habitats were colonised several times in the history by these flagellates. In the

field, final life-cycle stages, a/planozygotes, are frequently found. Attempts to cultivating them have

usually failed since cells are prepared for survival in harsh conditions after complete snow melt. The

objective of this study was to explore light requirements, morphology and phylogeny of snow algae

thriving in the Tyrolean Alps (Austria), the Giant Mountains (Czech Republic) and the High Tatra

Mountains (Slovakia, Poland). The focus was on species of the genus Chloromonas, which causes

green to orange and reddish snow. Surface cell wall ultrastructure was revealed by scanning light

microscopy showing aplanozygotes with flanges or spikes, and thus affiliated with current morphologic

descriptions of Chloromonas nivalis, Chloromonas rosae var. psychrophila and Chloromonas

brevispina. Localities above the timberline are also low light habitats, e.g. in deeper parts of the

snowpack, at steep snow slopes in proximity to boulders, and thus are in this respect similar to habitats

below the tree canopy. Comparison of the secondary structure prediction of the nuclear marker ITS2

rDNA with available sequences showed that the investigated algae represent several new species based

on the compensatory-base change species concept. In vivo chlorophyll fluorescence parameters were

obtained with a pulse – amplitude modulated fluorometer. Aplanozygotes were physiologically active.

Photoinhibition was noticed from 100 to 200 μmol photons m-2 s-1 upward. Our results suggest that the

biodiversity of snow algae in European mountain ranges is still underestimated.

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58th meeting of the czech phycological society 18. - 20. 9...

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