biology, genomics and evolution of the complex thalloids symposium... · 2015-06-27 · paralleling...
TRANSCRIPT
Biology, genomics and evolution of the
complex thalloids
14th-15th July 2015
With funding from the Royal Botanic Garden Edinburgh and the Sibbald Trust
Marchantia - Scale
Photo by D. Callaghan
Preissia - Carpocephalum
Photo by D. Callaghan
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Tuesday 14th July
9.15-9.45. Arrival and orientation
9.45-10.00. Welcome from RBGE’s Regius Keeper, Simon Milne
10.00-10.30. Diversity of complex thalloid liverworts
David G. Long
10.30-11.00. Amphitropical disjunctions in the complex thalloids
Robbert Gradstein
11.00-11.30. Coffee
11.30-12.00. The beginnings of microtranscriptome evolution in plants
Halina Pietrykowska, P. Piszczałka, S. Alaba, A. Pacak, I. Sierocka, P. Nuc, K. Singh, P. Plewka, A. Sulkowska, A.Jarmolowski, W.M. Karlowski, Z. Szweykowska-Kulinska
12.00-12.30. On Monocarpus (Monocarpaceae, Marchantiopsida), an isolated salt-pan
complex thalloid liverwort allied to the Sphaerocarpales
Laura L. Forrest, M.L. Hart, D.C. Cargill, J. Milne, D.G. Long
12.30-14.00. Lunch and poster session
with speed talk on Journal of Bryology Liz Kungu
14.00-14.30. Sex chromosome evolution in haploid dioecy
Peter Szövényi, S.F. McDaniel, A. Payton, M. Ricca
14.30-15.00. Food- and water-conducting systems in complex thalloids with sexual
reproduction thrown in
Jeff Duckett, S. Pressel
15.00-15.30. Coffee
15.30-16.30. Walk through gardens/glasshouses
16.30-16.45. Biosystematics and Ecology of Neotropical Cyathodium (Cyathodiaceae)
Noris Salazar Allen, H. Korpelainen, C. Chung, N. Gómez, N. Rivas
16.45-18.00. Microscopes available in lab.
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Wednesday 15th July
9.30-10.00. An update on the Marchantia genome
John Bowman, S. K. Floyd,T. Kochi, K.T. Yamato, K. Ishizaki, K. Berry, J. Jenkins, J. Schmutz
10.00-10.30. Evolution of sexual systems in complex thalloids
Masaki Shimamura
10.30-11.00. Development and evolution of the plant soil interface
Liam Dolan
11.00-11.30. Coffee
11.30-12.00. Scratching the surface: The Marchantia Cuticle
Sam Brockington, S. Pressel, J. Duckett
12.00-12.30. An overview of Malagasy Marchantiidae
Catherine Reeb
12.30-14.00. Lunch and poster session
14.00-14.30. Fungal associations in complex thalloids
Silvia Pressel, J.G. Duckett
14.30-15.00. RNA sequencing as a method of choice for the identification of genes
differentially expressed between male and female gametophytes producing
sex organs in simple thalloid liverwort Pellia endiviifolia
Izabela Sierocka, S. Alaba, W. Karłowski, Z. Szweykowska-Kulinska
15.00-15.30. Divergence times, evolution of morphological complexity and sexual
systems in a lineage with a slow molecular rate
Juan Carlos Villarreal, B.J. Crandall-Stotler, M.L. Hart, D.G. Long, L.L. Forrest
15.30-16.30. General discussion.
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An update on the Marchantia genome
Bowman, John1,2, Sandra K. Floyd1, 2Takayuki Kochi, 2Katsuyuki T. Yamato, 2Kimi Ishizaki, Kerry Berry3, Jerry Jenkins3, Jeremy Schmutz3
1School of Biological Sciences, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia; 2, Kyoto University, 3US DOE Joint Genome Institute
The origin of land plants was one of the major evolutionary events in the history of
planet earth. Experimental, paleontological, and morphological and molecular systematic data
all point to the liverworts as being some of the first plants to evolve and colonize the Ordovician
landscape. Thus liverworts are a key group to include in any comparative study aimed at
understanding the origin and evolution of organisms that now cover much of terrestrial earth.
We chose Marchantia polymorpha as a model liverwort due to (1) the slow rate of molecular
evolution in the Marchantiopsida, (2) the small genome size of M. polymorpha relative to more
basal liverwort taxa (i.e. the genomes of Haplomitrium and Treubia are 10x larger), (3) the
availability of genetic tools to manipulate gene function in M. polymorpha, and (4) the ubiquity of
M. polymorpha throughout the world and its ease of growth and genetics in laboratory settings.
In collaboration with JGI a draft sequence of the Marchantia polymorpha genome was generated.
Assemblies using 454 generated sequence had reduced mis-joining of scaffolds relative to
assemblies utilizing on paired end Illumina reads, however, the latter provided better coverage
and assemblies at some loci at a local level. A unique feature of the M. polymorpha genome
relative to those known from other land plants is the paucity of paralogs of genes encoding
regulatory molecules, which may be a consequence of the early evolution of dimorphic sex
chromosomes in the Marchantiopsida or possibly the Marchantiophyta resulting in a lack of
ancient whole genome duplications in liverworts.
Scratching the surface: The Marchantia Cuticle
Brockington, Sam1, Silvia Presel2, Jeffrey G. Duckett2
1Department of Plant Sciences, University of Cambridge, Downing Street Cambridge CB2 3EA, England 2Life Sciences Department, Plants Division, Natural History Museum, Cromwell Road, London, SW7 5BD, England
More accurate phylogenetic hypotheses coupled with the development of early land
plant model systems have accelerated research into the origin and early evolution of most land
plant adaptations. However research into the origin and evolution of the cuticle lags behind.
Indeed, even within well-established flowering plant models, our understanding of cuticle
genetics is still in its infancy. We have initiated a comparative genetic research program focused
on the plant cuticle, to identify the key events that underpin the evolution of the cuticle in land
plants. By coupling phylogeny, morphology, functional genetics and physiology, we hope to build
a comprehensive picture of cuticle function and evolution in early land plants. Our first step has
been to perform detailed descriptions of cuticle formation through the ontogeny of Marchantia polymorpha in order to more accurately evaluate phenotypes in the longer term. Here I present
some preliminary findings from this morphological analysis, together with techniques and
approaches we have developed to pursue a genetic approaches to cuticle evolution.
Development and evolution of the plant soil interface
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Dolan, Liam Department of Plant Sciences University of Oxford, OX1 3RB, England
Understanding how gene regulatory networks change during the course evolution is key
to understanding the origin of morphological diversity. Tip-growing filamentous cells such as
rhizoids and root hairs develop at the interface between land plants and the soil. These cells are
important for anchorage and nutrient acquisition in both vascular and non vascular plants and
play important roles in the interaction with soil microflora. These filamentous tip growing cells
constituted the entire “rooting” system of early diverging groups of land plants such as
liverworts and mosses. Vascular plants subsequently evolved specialized rooting axes – roots –
and these are covered in filamentous cells during some time in their life.
To gain insights into the mechanism that controlled the development of the first rooting systems
we have been comparing the developmental mechanism that control the development of
rhizoids in liverworts and mosses, and root hairs of seed plants. We carried out extensive
genetic screens in Marchantia polymorpha and generated genomic resources that we are happy
to share with others. We demonstrate that a network of RSL transcription factors controls the
development of rhizoids and root hairs in land plants. Marchantia polymorpha rsl1 mutants are
rhizoidless and mutations that result in overexpression of RSL1 cause the development of
ectopic rhizoids on the dorsal surface of the thallus. Taken together these data suggest that the
RSL genes acted in the last common ancestor of the extant land plants. Furthermore, we
demonstrate that RSL genes are also required for the differentiation of epidermis-derived organs
called gemmae. Insights into the evolution of these mechanisms illustrate how regulatory
networks and their functions can change during the course of land plant evolution.
Food- and water-conducting systems in complex thalloids with sexual reproduction
thrown in
Duckett, Jeff, Silvia Pressel Life Sciences Department, Plants Division, Natural History Museum, Cromwell Road, London, SW7 5BD, England
The very existence, let alone the functional significance, of food- and water-conducting
systems in complex thalloid liverworts is poorly appreciated. They are absent from both
generations in hornworts and from the sporophytes throughout liverworts. Bryophyte food-
conducting cells are characterised by vesicles, plastids and mitochondria longitudinally aligned
along arrays of endoplasmic microtubules and mixing of vacuolar and cytoplasmic contents
paralleling the same phenomenon in the sieve elements of tracheophytes. Whereas this cytology
is ubiquitous in the stems, sporophytes and rhizoids of bryopsid mosses in liverworts it is
restricted to Haplomitrium and several complex families particularly those harbouring fungal
symbionts. Here these cells form a distinctive region in the thalli between the dorsal air
chambers and the ventral fungus-containing cells. Their most likely function may be in
transporting of photosynthates to the mycobionts.
Water-conducting systems evolved at least three times in both mosses (Takakiopsida,
Polytrichopsida and Bryopsida) and liverworts (Haplomitrium, Pallaviciniaceae and
Marchantiopsida). Whereas in the first five groups these comprise perforate or imperforate
dead cells with variously thickened walls in the centre of the stems, setae and thalli, water
conduction in complex thalloids is via the pegged rhizoids. Though variously enclosed by scales
and ‘internalized’ within the grooves in carpocephala stalks, this system is external and thus
unique amongst all fossil and extant land plants. Like hydroids and sieve elements, pegged
rhizoids are dead at maturity. Their highly elastic walls and resistance to cavitation maintain
functional integrity through periods of desiccation. Dye movement experiments reveal that
water moves very effectively along the pegged rhizoids systems and, in carpocephala grooves, at
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comparable rates to those in moss hydroids. The pegged rhizoid apparatus is not only far more
effective than moss hydroids at maintaining full hydration in complex thalloids but even more
remarkably is also vital to their extraordinarily effective sexual reproduction. Our field
observations on wild populations of Marchantia have revealed fertilization distances of up to
18m with sporophytes being produced within almost 100% of the perianths whatever the
distance from the nearest male plants. Rain water is rapidly absorbed by the hydrophilic
antheridiophore caps and travels down the grooves taking spermatozoids with it. These are then
dispersed on surface water films. On reaching the vicinity of female plants the spermatozoids
reach the archegonia in the archegoniophore caps via a mixture of chemotaxis and upward
water movement between the pegged rhizoids in the carpocephala grooves.
On Monocarpus (Monocarpaceae, Marchantiopsida), an isolated salt-pan complex thalloid
liverwort
Laura L. Forrest1, Michelle L. Hart1, D.Christine Cargill2, Josephine Milne3, David G. Long1
1Royal Botanic Gardens Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, Scotland 2Australian National Herbarium Canberra, GPO Box 1600, Canberra, Australia 3Royal Botanic Gardens Melbourne, Australia
The phylogenetic placement of Monocarpus sphaerocarpus (Monocarpaceae), a member
of the complex thalloid liverworts with highly specialized morphology presumably related to its
saltpan habitat, has been determined based on molecular data. Within the complex thalloid
liverworts, Monocarpus resolves as sister to the Sphaerocarpales clade. Detailed ornamentation
of the spores of Monocarpus collections from Australia and South Africa, as revealed by SEM, is
reported, and some of the morphological features that unite and separate Monocarpus and the
Sphaerocarpales s. str. are discussed.
Amphitropical disjunctions in the complex thalloids
Gradstein, Robbert
Muséum National d’Histoire Naturelle, Paris, France
Plant disjunctions between the temperate regions of the northern and southern
hemisphere, commonly called amphitropical or bipolar disjunctions, have been discussed by
numerous authors but very little attention has been paid to the occurrence of such disjunct
distributions in the complex thalloids. A perusal of the literature revealed nineteen species in
seven genera (Asterella, Clevea, Corsinia, Oxymitra, Riccia, Riella, Sphaerocarpos) of
Marchantiopsida with amphitropical ranges. All of them are distributed in subtropical and
mediterranean regions of the northern and southern hemisphere but not (or very rarely) in the
Tropics. The majority of the species are disjunct between North and South America, few are
disjunct between Eurasia and southern Africa or Australia. The disjunct ranges are generally
based on morphological evidence; none have been tested using molecular data. The application
of modern molecular and phylogenetic methods to the study of amphitropical ranges in the
complex thalloids should be a fruitful approach for future study.
Speed talk: Journal of Bryology
Kungu, Elizabeth
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Royal Botanic Gardens Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, Scotland
Diversity of complex thalloid liverworts
Long, David G. Royal Botanic Gardens Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, Scotland
A short survey is presented of the five orders and twenty families of complex thalloid
liverworts. Using selected representatives of the 36 accepted genera, the range of morphological
diversity in vegetative and reproductive gametophytic structures is illustrated as well as
diversity of spore ornamentation. Eleven of the families contain only a single genus. The most
species-rich genera are Riccia in Ricciaceae and Asterella in Aytoniaceae
The beginnings of microtranscriptome evolution in plants : a case study of liverwort
Pellia endiviifolia
Pietrykowska, Halina1, Paweł Piszczałka1, Sylwia Alaba2, Andrzej Pacak1, Izabela Sierocka1, Przemyslaw Nuc1, Kashmir Singh1, Patrycja Plewka1, Aleksandra Sulkowska1, Artur Jarmolowski1, Wojciech M Karlowski2, Zofia Szweykowska-Kulinska1,2
1 Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland 2 Laboratory of Computational Genomics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
MicroRNAs are important regulatory elements of eukaryotic gene expression. These
short (18-24 nt) molecules act post-transcriptionally by sequence-specific guidance of RNA
Induced Silencing Complex (RISC) to complementary mRNAs which results in slicing or
translation inhibition of targeted mRNAs. We applied the high-throughput sequencing technique
(SOLEXA, Illumina) and sequenced sRNAs, transcriptome, and degradome from the dioecious
liverwort Pellia endiviifolia. 311 miRNA families of conservative miRNA that are identical to
model moss Physcomitrella patens and/or other land plants miRNAs were identified.
Interestingly, three of the liverwort miRNAs show high similarity to previously reported miRNAs
from Chlamydomonas reinhardtii. We confirmed the presence of selected C. reinhardtii miRNAs
by northern hybridization using RNA isolated from P. endiviifolia in vitro plants. Also, the
presence of selected conservative miRNAs with homologs in higher land plants identified in P. endiviifolia was confirmed by northern hybridization. Using bioinformatic approaches we
studied also novel potential miRNA for P. endiviifolia. 42 new liverwort-specific miRNAs were
discovered. Analysis of P. endiviifolia transcriptome revealed the presence of at least twenty
putative miRNA precursors. Ten of them were verified using experimental approaches (RACE
and genome walking) resulting in establishing the gene structure of the first known liverwort
MIR genes and their primary transcripts. Four of identified MIR genes contain one or more
introns. The RNA degradome analysis revealed that target mRNAs of only three miRNAs
(miR160, miR166, and miR408) have been conserved between liverworts and other land plants.
New targets were identified for the remaining conserved miRNAs. Moreover, the analysis of the
degradome permitted the identification of targets for 13 novel liverwort-specific miRNAs. This
new data supplement our knowledge and understanding of plant miRNA evolution and
represent an interesting example of research case for other scientists.
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Fungal associations in complex thalloids Pressel, Silvia, Jeffrey G. Duckett
Life Sciences Department, Plants Division, Natural History Museum, Cromwell Road, London, SW7 5BD, England
The evolution of fungal symbioses was one of the key events in the colonization of land
by plants over 480MYA. Today up to 90% of all land plants, with representatives from every
major lineage except mosses, have fungal symbionts. Because of their sister position to the
Haplomitriopsida at the foot of the land plant tree, complex thalloid liverworts are particularly
important for furthering understanding of the evolution and biology of land plant-fungal
symbioses, the appreciation of which has undergone seminal shifts over the last five years. Prior
to this, extensive ultrastructural data, across both complex and simple thalloid liverworts,
appeared to lend unquestioned support to the monolithic paradigm that glomeromycote fungi
were the ancestral mycobionts albeit with no functional studies confirming mutualism in these
groups. Following the 2011 discovery that the Haplomitriopsida exclusively harbour
Mucoromycotina, an earlier fungal lineage than the Glomeromycota, our collaborative multi-
disciplinary research is now revealing that associations involving Mucoromycotina and/or
Glomeromycota – with both fungal symbionts sometimes co-occurring in the same host (dual
partnerships) – are widespread in early divergent lineages of complex thalloids (e.g.
Neohodgsonia, Lunularia) whilst more derived groups are either fungus-free (e.g. Riccia,
Monocarpus) or Glomeromycota-specific (e.g. Marchantia, Preissia). All associations investigated
so far have been shown to be mutualistic, involving reciprocal exchange of organic carbon and
nutrients between partners. However their responses to simulated ancient and modern
atmospheric CO2 concentrations vary dramatically: whilst complex thalloids harbouring
Mucoromycotina +/- Glomeromycota benefit from lower, near modern-day a[CO2], as is also true
of tracheophytes-Glomeromycota partnerships (mycorrhizas), the efficiency of complex-
thalloids-Glomeromycota exclusive associations increases considerably under ancient elevated
a[CO2]. Although requiring further plant and fungal sampling, our current understanding of the
phylogenetic distribution of fungal symbioses in complex thalloids points to the loss of the
ancestral Mucoromycotina partnership – with the basal Sphaerocarpales and Blasiales both
fungus-free - and the subsequent reacquisition of the same plus Glomeromycota, with dual
partnerships being possibly the prevailing symbiotic strategy. Why more derived clades engage
exclusively with Glomeromycota fungi, an apparently ‘losing’ strategy under modern day a[CO2]
resulting from the a[CO2] decline in the late Paleozoic, remains conjectural. Also problematic,
given the widespread occurrence of both types of mycobiont in complex thalloids whose
cytology of colonization has so far unquestionably been interpreted as typically
glomeromycotean, is our understanding of structural differences and/or similarities between
different fungal partners – for example are arbuscules the ‘exclusive signature’ of
Glomeromycota symbioses? We will discuss these questions and other wider implications of
our research for understanding the evolution and biology of fungal symbioses in land plants.
An overview of malagasy Marchantiidae
Reeb, Catherine Institut de Systématique, Évolution, Biodiversité ISYEB - UMR 7205 - MNHN, UPMC, CNRS, EPHE Muséum National D'histoire Naturelle 57 rue cuvier, Case postale 39 FRANCE-75005 Paris
Madagascar is an under-explored country from a bryological standpoint and no synthetic
study has been attempted on complex thalloid liverworts. I began to explore historical and
recent collections in order to make a synthesis of our current knowledge on the Malagasy
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Marchantiidae. Sixteen taxa are recognized with eight new records for the island. Among the
order Marchantiales, the family Ricciaceae has been particularly underexplored, which could
explain the difference between the more than fifty species recognized in South Africa and only
five species recorded in Madagascar. My research aims at re-examining species delimitation and
local endemism (especially in Ricciaceae), as the starting point to test evolutionary hypotheses
about origin and radiation of Malagasy Marchantiidae.
Biosystematics and Ecology of Neotropical Cyathodium (Cyathodiaceae)
Noris Salazar Allen1, Helena Korpelainen2, Clementina Chung1†, N. Gómez1 & N. Rivas1
1Smithsonian Tropical Research Institute, Panama 2Department of Agricultural Sciences, P.O. Box 27 (Latokartanonkaari 5), University of Helsinki, Finland
Cyathodium is a thalloid liverwort with 12 species distributed in the Paleotropics, the
Neotropics and one report for northern Italy. The center of diversity appears to be India with
eight species. Five species occur in the Neotropics: C. bischlerianum Salazar Allen, C. cavernarum
Kunze, C. foetidissimum Schiffn., C. spruceanum Prosk. and C. steerei Hässel. Three of these are
endemic to the Neotropics: C. bischlerianum, C. spruceanum and C. steerei. The plants grow on
soil along riverbanks, caves, bark in forest, rocks around waterfalls or creeks, cement road
ditches, floors, stairs, flower pots, sometimes in arable fields in humid places. They are seasonal
plants and are not drought-tolerant but can perennate by ventral tubers. Plants of Cyathodium
are characterized by having two layers of cells that cover air chambers separated by vertical
rows of cells and opening to the outside by pores. Some species have a multistratose área (e.g., C. steerei), a pseudocosta. Three of Neotropical species are dioicous and two monoicous.
Neotropical species can be distinguished morphological, molecular (nucleotide sequence
variation in the nuclear ribosomal DNA región, ITS1-5.8S rRNA-ITS2, for four species)and
chemically. Fresh collections and additional axenic cultures will be started to compare the
chemical composition obtained in 2004 with those that will be obtained in 2015, using samples
from the same populations tested before.
Evolution of sexual systems in complex thalloids
Shimamura, Masaki
Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, 739-8526, Japan
As for a process of fertilization in complex thalloid liverworts, there is a commonly held
view that raindrops hit the disk of mature antheridiophore and splashed sperms swim in the
water for the archegonia. However, actually, complex thalloid liverworts have evolved more
efficient system for fertilization. Many marchantialian liverworts typically discharge the sperm
cells into the air from the antheridial disk. Especially in Conocephalum, sperm cells are dispersed
over great distances by the wind. Although stalked antheridiophore of Marchantia ooze the
sperm cells moderately into the water on the antheridial disk, the bundles of rhizoids seem to
work as effective conduits for sperms. The bundles of pegged rhizoids extended continuously
from ventral surface of female plants to just beside archegonia through the grooves of the
archegoniophore stalk. Sperms were able to move up the grooves by capillary action among the
bundles of pegged rhizoids. Successful fertilization was achieved by just adding the sperm
suspension to the edge of female plants without direct water-splash from the disk of
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antheridiophore. The function of the bundles of pegged rhizoids seems to be not only to conduct
water and nutrients, but also to absorb and concentrate the sperms around the hanging
archegonia on the receptacle of the archegoniophore.
RNA sequencing as a method of choice for the identification of genes differentially
expressed between male and female gametophytes producing sex organs in simple
thalloid liverwort Pellia endiviifolia sp B
Sierocka, Izabela1, Sylwia Alaba2, Wojciech Karłowski2, Zofia Szweykowska-Kulinska1,2
1 Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland 2 Laboratory of Computational Genomics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
Regulation of gene expression plays a pivotal role in controlling all aspects of
multicellular organisms development, including sexual reproduction. In flowering plants a
number of genes has been identified which control the transition from vegetative to generative
phase of life cycle. Among liverworts, the most basal lineage of bryophytes, there is almost no
data about the genes and mechanisms controlling this transition. This fact puts liverworts in
critical evolutionary position to investigate the genetic basis of key innovations which allowed
them to survive in demanding terrestrial environment and to give fertile offspring. We have
chosen Pellia endiviifolia species B, a dioecious liverwort from class Jungermaniopsida to profile
the differences in transcripts level between different stages of the male and female thalli
development. We applied the next generation sequencing technology to identify genes engaged
in the antheridia and archegonia production in P.endiviifolia. RNA-seq was performed using four
different developmental stages: the male thalli i) producing or ii) without antheridia, the female
thalli iii) producing or iv) without archegonia. For each library over 40 mln reads were
generated which were mapped to the reference de novo transcriptome sequencing data of P. endiviifolia. To select genes with the highest differences in expression between the male and
female thalli producing/not producing sex organs bioinformatics analyses were performed with
criterion log2_fold_change ≥ 10. As a result 72 Differentially Expressed Genes (DEGs) were
selected. Out of 10 genes up-regulated in sperm-producing male thalli, 8 are also expressed in
the vegetative phase of males thalli. In turn, out of 62 up-regulated genes in archegonia-
producing female thalli, 46 are also expressed in the vegetative phase of female growth. To
verify the differentially expressed genes selected from the RNA-seq, real-time PCR analysis was
performed which validated 9 male and 47 female specifically expressed genes. The most
enriched DEGs belong to RNA or DNA binding protein families, serine/threonine-protein
phosphatases, LRR receptor-like kinases and ubiquitin protein ligases. 24 DEGs showed no
similarity to known proteins or nucleotide sequences, and the lengths of these transcripts reach
from ~250 to ~600nt with no putative open reading frames. It cannot be excluded that these
transcripts represent non-coding RNAs or represent partial sequences of untraslated regions of
original mRNA molecules what needs to be further investigated.
Our studies provide possibility to learn about the gene expression regulation within the
representative of genus Pellia, which is recognized as the one of the most basal lineage of the
simple thalloid liverworts. The work was supported by the Foundation for Polish Science, grant
number POMOST/2012-5/7.
Sex chromosome evolution in haploid dioecy
Szövényi Peter1, Stuart F. McDaniel2, Adam Payton2, Mariana Ricca 1
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1 Institute of Systematic Botany, University of Zurich, Switzerland 2 University of Florida Gainesville, Gainesville, Florida, USA
Bryophytes, especially liverworts, represent an appropriate model system to investigate
the evolution of sex chromosomes and sex determination in haploid dioecy. In particular,
genomic data available for Marchantia polymorpha and related species provides a unique
opportunity to resolve these long-standing evolutionary issues at the genomic scale. Our group
is using M. polymorpha as a model system to study two major questions surrounding the topics
of sex determination and the evolution of sex chromosomes in haploid dioecy. The projects and
the approach we are following are discussed in details below.
(I.) In diploid dioecious diploid organisms, where sex determination is governed by
dimorphic sex chromosomes, sex chromosomes are expected to differ in genetic variability, size,
gene content and gene expression due to asymmetric heterozygosity and suppression of
recombination. By contrast, in haploid dioecy, sex chromosomes are equally heterozygous and
show suppressed recombination in a similar extent. Therefore, if sex-specific evolutionary forces
are negligible, sex chromosomes under haploid dioecy are expected to be influenced by similar
evolutionary forces and should follow similar evolutionary trajectories. Nevertheless,
experimental evidence contradicts this hypothesis in several aspects and suggests that U and V
chromosomes differ in size, gene content and level of degeneration. Therefore, we aim to
understand in what extent and why evolutionary trajectories of sex chromosomes under haploid
dieocy deviate from theoretical predictions.
(II.) Dioecy is also assumed to be the ancestral condition in liverworts. In line with that, U
and V sex chromosomes of Marchantia appear to be considerably old suggested by their gene
content and genetic divergence. However, whether the sex determination system and U/V sex
chromosomes have evolved only once or multiple times independently is not known.
Importantly, abrupt changes from dioecy to monoecy have occurred multiple times and
independently during the phylogenetic history of liverworts suggesting that the sex
determination system may be labile and might have evolved multiple times. Therefore, it is
currently unknown whether U and V chromosomes have evolved multiple times from the very
same autosomes in all liverworts and what sort of genomic changes have contributed to the
sudden switch in mating system along the liverwort phylogeny. In this second research direction
we are investigating the genomic changes that have accompanied the dioecy-monoecy transition
which will inform us on the general rules governing sex determination and sex chromosome
evolution in haploid dioecy.
We are currently conducting two major experiments that correspond to the two research
directions outlined above. In the first experiment we are analyzing the genetic constitution
(GBS), sex and phenotypic traits of approx. 200 segregants (single spore isolates) generated by
crossing Tak1 and a local Swiss strain of M. polymorpha. With this experiment we aim to identify
genes linked to the U and V chromosomes with high confidence. To contrast the molecular
evolution of sex- and autosome-linked genes we genotype U/V-specific and autosomal genes in a
panel of approx. 200 natural isolates collected around the world. To aid SNP discovery we have
also re-sequenced both parental strains.
To investigate the second set of questions we are conducting a comparative genomic
analysis of Preissia quadrata and M. polymorpha. P. quadrata is a close relative of M. polymorpha
but often behaves as a monoicous species, produces both male and female gametangia on the
very same thallus. Both species have nine chromosomes and a comparable genome size. We are
currently sequencing and analyzing the P. quadrata genome and investigate how sex
chromosomes arose in the Marchantia lineage. We intend to identify whether dioecy or monoicy
is ancestral to the group and through which genomic processes (chromosomal rearrangements,
fusions) sex chromosomes have originated. In the future we are planning to extend our
sequencing effort to other liverwort genomes to identify whether the patterns discovered hold
in multiple independent lineages of liverworts.
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Divergence times, evolution of morphological complexity in a lineage with a slow
molecular rate
Villarreal A, Juan Carlos 1; Barbara J. Crandall-Stotler2; Michelle L. Hart1; David G. Long1; Laura L. Forrest1,3 1Royal Botanic Gardens Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, Scotland 2Department of Plant Biology, Southern Illinois University, Carbondale, IL, USA
The fossil occurrence of cryptospore dyad and tetrad assemblages signals the formation
of a terrestrial flora around 450 million years ago. Bryophytes (hornworts, liverworts and
mosses) are the extant relatives of the colonizing terrestrial flora and hold the morphological
and genomic clues to understand the evolutionary pressures faced by the early land colonizers.
The development of genomic resources for the liverwort Marchantia polymorpha, which is
emerging as a new model system for evolutionary and synthetic biology, will undoubtedly
provide insights to the genetics underpinning land plant structures and the challenges faced by
the earlier land colonizers. The complexity of the complex thalloids, a group including the model
system organism Marchantia polymorpha, derives from the layered anatomy of the thalloid
gametophyte, which is differentiated into a dorsal, nonclorophyllose epidermis, an upper
photosynthetic, assimilatory zone, a parenchymatous, non-photosynthetic storage zone, and a
ventral epidermis that bears rows of scales and rhizoids. In most genera, the assimilatory zone
contains abundant, schizogenously derived air chambers that are confluent with epidermal
pores. The complex thalloids are thus one of the earliest land plant lineages to have evolved
internalized gas exchange tissues. In order to understand when and where these morphological
innovations occurred, it is necessary to resolve the backbone phylogeny of the complex thalloid
liverworts. Here, based on a complete generic phylogeny that includes 98 samples representing
all 36 genera, a large molecular dataset and a fossil-calibrated timetree we address the
morphological and molecular evolution of the group. We address the branching pattern amongst
early divergent lineages of complex thalloids, diversification times, rates of evolution and
evolution of morphological complexity evolve within Marchantiopsida, in particularly focused on
the carpocephalum, air chambers and sexual systems.
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Posters
Substantial sequence differentiation of three cpDNA genes between cryptic species within
Conocephalum conicum /salebrosum complex.
Hanna Kijak, Aleksandra Spychała, Ireneusz Odrzykoski
A. Mickiewicz University, Faculty of Biology, Poznań, PL-61614, Poland,
The liverwort genus Conocephalum Hill is composed of three morphospecies: C. conicum L. (Dum), recently described C. salebrosum Szweyk. Buczk. Odrzyk. and C. japonicum (Thunb.)
Grolle. It was postulated that both C. conicum and C. japonicum include four and three cryptic
species respectively, with more restricted allopatric distribution. Originally, genetic
differentiation was studied using isozyme markers (Odrzykoski, Szweykowski 1991, Akiyama,
Hiraoka 1994, Miwa 2004). The aim of this study was to analyze the sequence differentiation of
large fragments of three chloroplast genes: rbcL, matK, psbA (and additionally trnK-psbA
intergenic spacer) to examine whether studied sequences contain mutations, which can be used
in the identification of cryptic species. Samples used in this study represent all known cryptic
species supplemented by sequences from two publications (Kim et al. 2001, Miwa et al, 2009).
All analyzed sequences shown the presence of species specific substitutions. Within the
intergenic region trnK- psbA we have also detected indels. The differences between cryptic
species ranged between 0.001 to 0.011 substitutions per site. Most of the observed substitutions
(70%) are synonymous. Intraspecific differentiation within cryptic species is very low except C. salebrosum sampled from the whole Holarctic range. We conclude that diagnostic mutations
within psbA and two DNA barcode genes (rbcL, matK), are useful as species specific molecular
markers within the Conocephalum conicum/salebrosum complex. (This study has been supported by the NCN Grant no. N303 800340.)
The complex thalloids (Marchantiophyta) in Cuba: challenges and perspectives
Yoira Rivera Queralta Centro Oriental de Ecosistemas y Biodiversidad (BIOECO). Ministerio de Ciencia, Tecnología y Medio Ambiente (CITMA). Santiago de Cuba, Cuba.
The main challenge of the botanists in Cuba is to upgrade bryological studies of the
island. The present work aims at revising the state of the knowledge of the complex thalloids
(Marchantiopsida) of Cuba. The Cuban species are listed and some aspects of their distribution
and conservation are evaluated.
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List of attendees (*speakers)
Bell, Neill Science Department, Royal
Botanic Garden Edinburgh,
20A Inverleith Row
Edinburgh EH3 5LR
Bowman, John* School of Biological Sciences,
Monash University, Clayton
Campus, Melbourne, Victoria
3800, Australia
Brockington, Sam* Department of Plant Sciences,
University of Cambridge,
Downing Street Cambridge
CB2 3EA, England
Callaghan, Des [email protected]
Cox, Cymon FCT Investigador -
Coordinating Researcher
Plant Systematics and
Bioinformatics Research
Group (PSB)
Centro de Ciencias do Mar
(CCMAR) - CIMAR-Lab. Assoc.
Dolan, Liam*
Department of Plant Sciences
University of Oxford, OX1
3RB, UK
Duckett, Jeff* Natural History Museum,
Cromwell Road, London, SW7
5BD, England
Forrest, Laura L.* Science Department, Royal
Botanic Garden Edinburgh,
20A Inverleith Row
Edinburgh EH3 5LR
Gradstein, Robbert*
Muséum National d’Histoire
Naturelle, Paris, France
Horwath, Aline Department of Plant Sciences,
University of Cambridge,
Downing Street Cambridge
CB2 3EA, England
Kijak, Hanna A. Mickiewicz University,
Faculty of Biology, Poznań,
PL-61614, Poland
Kungu, Elizabeth* Science Department, Royal
Botanic Garden Edinburgh,
20A Inverleith Row
Edinburgh EH3 5LR
Long, David G.* Science Department, Royal [email protected]
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Botanic Garden Edinburgh,
20A Inverleith Row
Edinburgh EH3 5LR
Pietrykowska, Halina*
Department of Gene
Expression, Institute of
Molecular Biology &
Biotechnology, Faculty of
Biology, Adam Mickiewicz
University, Poznan, Poland
Pressel, Silvia* Natural History Museum,
Cromwell Road, London, SW7
5BD, England
Reeb, Catherine*
Muséum National d’Histoire
Naturelle, Paris, France
Rivera Queralta, Yoira Centro Oriental de
Ecosistemas y Biodiversidad
(BIOECO). Ministerio de
Ciencia, Tecnología y Medio
Ambiente (CITMA). Santiago
de Cuba, Cuba.
Salazar Allen, Noris Smithsonian Tropical
Research Institute, Panama
Shantanu, Kumar Department of Botany
Deshbandhu College,
University of Delhi, India
Shimamura, Masaki*
Department of Biological
Science, Graduate School of
Science, Hiroshima
University, Kagamiyama 1-3-
1, Higashi-Hiroshima, 739-
8526, Japan
Sierocka, Izabela* Department of Gene
Expression, Institute of
Molecular Biology &
Biotechnology, Faculty of
Biology, Adam Mickiewicz
University, Poznan, Poland
Szövényi, Peter*
Institute of Systematic
Botany, University of Zurich,
Switzerland
Villarreal A., Juan Carlos* Science Department, Royal
Botanic Garden Edinburgh,
20A Inverleith Row
Edinburgh EH3 5LR
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