Dec 022016
 
Some of the herbarium collections of Marchantia held in the RBGE herbarium

Some of the herbarium collections of Marchantia held in the RBGE herbarium

Many new species are already included in natural history collections around the world, it’s just that nobody has yet got around to examining the material, recognising that it represents something novel, and publishing a name for it. Sometimes these new species are filed under the epithet of a similar named species, sometimes they’re just filed under the genus name with other collections that have not been identified to species, and sometimes they have been annotated to recognise that they’re probably distinct from all the species that have already been described, e.g., as “sp. nov.

David Long has made a huge number of plant collections from around the world in his 40-plus year botanical career, with many of these collections not yet fully examined. Some of this material is being mined for DNA sequencing projects at RBGE, and for some of our key plant groups, as well as sequencing well-identified material, we are also sequencing plants that have not been assigned to species. Molecular lab work is fast compared to close morphological studies of multiple plant specimens; this can therefore speed up the processes of traditional taxonomy, by allowing it to focus on things that are obviously distinct.

One lineage that David Long is particularly involved with, and that remains one of our key plant groups, is the complex thalloid liverworts. Some of our sequencing work has involved Marchantia, which made Xiang et al.‘s recent description of a new species in the genus, Marchantia longii, particularly interesting. In the last few days, the DNA sequences that were included in the paper were made publicly available on the NCBI site, GenBank. One of the regions that was sequenced by Xiang et al., the plastid-encoded RuBisCo Large subunit gene rbcL, was also included in our study, and so I was able to put the two data sets together, and see how the new species fits into our phylogenies.

The results are interesting: When Xiang et al. named M. longii, they did so in part because the area that the plant came from, in northwestern Yunnan, is one in which David has been very active. In fact, at RBGE we had already generated DNA sequence data from nine accessions of Marchantia that David had collected there. I was delighted to find that two of these accessions (collections Long 36155 and Long 34642), which had been filed in our collections without a specific epithet, are an exact genetic match to Marchantia longii. It seems that David really does have an affinity for the plant, having gone out and found some even before it was named for him!

 

Long’s Marchantia

A rapid phylogeny of Marchantia, from the RBGE collections. II. Illuminating our sampling

A rapid phylogeny of Marchantia, from the RBGE collections. I. Sampling

Nov 222016
 
David Long in Gaoligong Shan; photo by Dong Lin

Dr David Long in Gaoligong Shan; photo by Dong Lin

Formerly the head of our Cryptogam section, and currently an extremely active RBGE Research Associate, David Long is well known and respected for his botanical work in the Himalayas, and for his bryological research. He has collected a huge number of taxonomically and phylogenetically interesting bryophytes on numerous plant collecting expeditions, collaborating with researchers around the world. His 2006 monograph on Eurasia Asterella reflects a special interest in the complex thalloid liverworts (Marchantiopsida), which has formed a focal point for subsequent research at RBGE on the systematics of the group (e.g., Villarreal et al. 2015).

Marchantia longii, from Fig. 1, Xiang et al. 2016, The Bryologist

Marchantia longii, from Fig. 1, Xiang et al. 2016, The Bryologist

In October this year, Chinese colleagues You-Liang Xiang, Lei Shu and Rui-Liang Zhu, using morphological and molecular evidence, described a new species of Marchantia from the northwestern region of Yunnan. Their paper, in the American Bryological and Lichenological Society journal The Bryologist, suggests that this is a distinct species, phylogenetically related to Marchantia inflexa, M. papillata and M. emarginata.

Xiang et al. 2016, The Bryologist

Fig. 4, Xiang et al. 2016, The Bryologist

The new species differs morphologically from other Marchantia species in the area by a suite of pore, thallus and receptacle characters, one of the most obvious of which is its very large epidermal pores, which can clearly be seen in the photographs presented by Xiang et al. The authors have named their new plant Marchantia longii R.L.Zhu, Y.L.Xiang et L.Shu, in honour of David, because he is “the specialist of complex thalloid liverworts and made several bryological expeditions in northwestern Yunnan, China”.

On these expeditions to the area, David collected extensively. It remains to be seen, however, whether his own collections include any plants of the newly named Long’s Marchantia!

Sep 082016
 

One of the main problems with sampling largely from herbarium specimens, rather than from material that has been specifically collected for DNA work (rapidly dried in silica gel then maintained at low humidity), is that the quality of the DNA is unpredictable and usually rather poor. Therefore, despite starting out with 169 accessions and about 20 species of Marchantia, the actual successes, where we were able to get good quality DNA sequence data, were substantially lower. What we currently have is a slightly unbalanced data matrix, with 82 Marchantia accessions for rbcL, and 78 Marchantia accessions for psbA-trnH.

Reboulia hemisphaerica thallus, photographed by David Long (Long 34254)

Reboulia hemisphaerica thallus, photographed by David Long (Long 34254)

We also sequenced both rbcL and psbA-trnH from material of two accessions that we thought were Marchantia but where the sequences turned out to be Reboulia (from Texas) and Wiesnerella (from Bhutan). A quick check of the herbarium voucher specimens for both of these showed that they represented mixed collections of more than one complex thalloid species, for which the “wrong” plant parts had ended up in our silica dried tissue collection. Taking fortune from misfortune, both Reboulia and Wiesnerella form quite adequate outgroups for the phylogeny!

Wiesnerella denuda, photographed by David Long

Wiesnerella denuda thallus, photographed by David Long (Long 36267)

Out of the 20 species that we HAD hoped to sample, we ended up with only 12 named Marchantia species for rbcL (Marchantia polymorpha, M. paleacea, M. linearis, M. papillata, M. inflexa, M. emarginata, M. pinna, M. chenopoda, M. debilis, M. hartlessiana, M. quadrata and M. romanica), and 15 for psbA-trnH (Marchantia polymorpha, M. paleacea, M. linearis, M. papillata, M. inflexa, M. emarginata, M. pinna, M. chenopoda, M. debilis, M. globosa, M. pappeana, M. hartlessiana, M. subintegra, M. quadrata and M. romanica); we also had three Marchantia polymorpha subspecies (polymorpha, ruderalis and montivagans) and two Marchantia paleacea subspecies (paleacea and diptera).

That’s a little disappointing, representing, as it does, fewer than half of the 38 currently recognised species in the genus. However, we did also sequence a number of Marchantia accessions that had not been determined to species, and although many of them were good DNA matches to species that we had sampled, several are clearly different to everything else that we have included: one distinct lineage in Yunnan, China, another that occurs in Yunnan and Nepal, and a third in Indonesia and Malaysia. That’s balanced again by taxa that may not have been identified correctly; the psbA-trnH sequences from African material of M. debilis, M. globosa, M. pappeana and M. polymorpha, for example, are identical.

Intriguingly, in the “Preissia” clade, as well as M. romanica, there appear to be two lineages of Marchantia quadrata, one consisting of accessions from Denmark, Sweden and Sichuan, China, and the other with accessions from Svalbard, Norway and Utah, USA. These may tie in with subspecies quadrata (for the first lineage) and subspecies hyperborea (for the material from Svalbard and Utah), but the degree of genetic divergence is far higher than that found between many of the recognised species in Marchantia. It is a bit disconcerting, however, to notice that we have managed to overlook any Marchantia quadrata material from Scotland in our sampling!

The next step in the project, before it’s time to reveal any of the phylogenetic trees I’ve alluded to, is a phase of reciprocal illumination where we reconcile morphological information from the herbarium specimens with the information derived from the molecular sequence data. In other words, it’s time to double check our plant identifications, a part of the project that’s now in the capable hands of Dr David Long; the pile of Marchantia specimens is already on his desk!

 

 

Relevant posts

A rapid phylogeny of Marchantia, from the RBGE collections. I. Sampling

A rapid phylogeny of Marchantia, from the RBGE collections. II. Illuminating our sampling

Jul 202016
 

Not long ago, the only non-crop plant that the mainstream scientific community seemed to be aware of was the brassica Arabidopsis thaliana – easily cultivated, with a short generation time and small nuclear genome, it seemed the perfect plant model. The model moss Physcomitrella patens came along some years later, again with a short generation time and small genome and with easy protocols for cultivation, but with the addition of a haploid dominant lifecycle and the ability to undergo efficient homologous recombination. A far more recent addition to the pool of available model organisms is the complex thalloid liverwort Marchantia polymorpha. Like Physcomitrella, the haploid part of the plant’s lifecycle is dominant, the nuclear genome is small, the plants are easy to cultivate and fast growing, and there are established protocols to get them into sexual phases. Genetic transformation is also straightforward, and because the thalloid plant is haploid, the effects of mutations are easily visible and can be propagated via vegetative clones.

model system posterIndicative of its growing popularity as a model organism, the February 2016 edition of Plant and Cell Physiology, edited by Professors John Bowman, Takashi Araki and Takayuki Kohchi, was a special focus edition on Marchantia polymorpha, while in June this year, EMBO hosted an international workshop on new model systems for early land plant evolution, wherein 21 of 36 speakers (58%) and 43 of 67 poster presenters (64%) mentioned Marchantia in their abstracts.

Marchantia sampling from Villarreal et al. 2015

Marchantia species sampling from Villarreal et al. 2015, New Phytologist

With publications starting to emerge from the longstanding RBGE project on the phylogeny of complex thalloid liverworts, we felt it was time to also explore some of the species level variation within genera. Previous published work from RBGE examines species relationships in other complex thalloid groups, Dumortiera, Cleveaceae and Mannia, while we are currently working on manuscripts for Sphaerocarpos and for the Aytonicaeae.

Some of the herbarium collections of Marchantia held in the RBGE herbarium

Some of the collections of Marchantia held in the RBGE herbarium

Boxes of silica-dried liverworts in RBGE's tissue storage room

Boxes of silica-dried liverworts in RBGE’s tissue storage room

Considering the current levels of interest in Marchantia, and in light of our recent paper sinking both Preissia and Bugecia into the genus, we did a rapid survey of our silica-dried tissue and herbarium collections, to see how feasible it was to flesh out the sampling in our 2015 paper (which included about 8 species), to produce the first phylogeny for species of Marchantia. In 2013-2014, we extracted DNA from all our silica-dried tissue collections, and from many of the most recent herbarium collections, which in combination with sampling for our complex thalloid phylogeny, various EU-funded SYNTHESYS projects, and ongoing DNA barcoding work, meant that we now have DNA extracted from 169 Marchantia accessions, which have been determined to represent ca. 20 species, out of a total of 38 accepted species in the genus.

Marchantia polymorpha ssp montivagans, photographed in Merida, Venezuela by David Long

Marchantia polymorpha ssp montivagans, photographed in Merida, Venezuela by David Long (Long 33064)

However, nearly 45% of the accessions (76) are detted as Marchantia polymorpha, as some of our previous work has focused on investigating the genetic differences between its three recognised subspecies, ruderalis (the common, weedy form), polymorpha (from damp natural habitats) and montivagans (frequently an upland plant). Most of the Marchantia polymorpha accessions are from the UK, but there are also samples from Ireland, Portugal, Sweden, Latvia, Switzerland, France, China, Malaysia, Pakistan, Tanzania, the US, Canada, Argentina, Ecuador and Peru.

The other species that we have extracted DNA for are M. alpestris, from Greenland; M. berteroana, from Chile and New Zealand; M. chenopoda, from Ecuador and Mexico; M. debilis from Cameroon, Ghana and South Africa; M. emarginata, from China and Japan; M. foliacea, from New Zealand; M. globosa, from Reunion; M. hartlessiana, from Bhutan, India and Nepal; M. inflexa, from Mexico; M. linearis, from Bhutan and Nepal; M. paleacea, from Italy, Portugal, the US, Mexico, Yemen, India, Bhutan, China and Japan; M. papillata from Bhutan, Bangladesh, Nepal, Rhodesia, Tanzania and Malawi; M. pappeana from Lesotho, Tanzania and Malawi; M. pinnata from Japan; M. plicata from Ecuador, and M. subintegra from Bhutan, India and Nepal.

Marchantia quadrata, photographed in the US by David Long (Long 35670)

Marchantia quadrata, photographed in the US by David Long (Long 35670)

In addition, we have accessions of Marchantia romanica (formerly Bucegia romanica) from Romania and Slovakia, and accessions of Marchantia quadrata (formerly Preissia quadrata), from the UK, Ireland, France, Germany, Sweden, Norway, the Czech Republic, China and the US.

The choice of which DNA regions would be best to work with was straightforward – given that many of our DNA extractions were from herbarium specimens, we were limited to short regions of sequence, and to regions that are present in multiple copies within the plant genome – effectively, plastid and nuclear ribosomal regions. When specimens are preserved for the herbarium, the quality of their DNA drops considerably compared to fresh material; eventually it can break into many short fragments. In order to make copies of regions of DNA using standard laboratory PCR methods, there has to be an unbroken piece of DNA to act as the template, and the shorter the region that’s being copied, and the more copies of it that are present in the genome, the more likely it is to work. Because we routinely sequence the two standard plant DNA barcode loci, from the plastid rbcL and matK genes, and two supplementary DNA barcode regions, the plastid psbA-trnH spacer region and the nuclear ribosomal spacer ITS2, these relatively short regions were obvious choices. However, we found two of these regions, matK and ITS2, consistently problematic to amplify and to sequence for Marchantia polymorpha, and so decided to focus on just the rbcL and psbA-trnH regions for this initial study.

 

References:

David G. Long. 2010. Marchantia polymorpha subsp. montivagans/polymorpha/ruderalis, in: Atherton, Bosanquet & Lawley, Mosses and Liverworts of Britain and Ireland a field guide, British Bryological Society.

David G. Long, Laura L. Forrest, Juan Carlos Villarreal & Barbara J. Crandall-Stotler. 2016. Taxonomic changes in Marchantiaceae, Corsiniaceae and Cleveaceae (Marchantiidae, Marchantiophyta). Phytotaxa 252 (1): 077-080.

Juan Carlos Villarreal, Barbara J. Crandall-Stotler, Michelle L. Hart, David G. Long & Laura L. Forrest. 2015. Divergence times and the evolution of morphological complexity in an early land plant lineage (Marchantiopsida) with a slow molecular rate. New Phytologist. 209: 1734–46, doi: 10.1111/nph.13716.

Relevant posts:

A rapid phylogeny of Marchantia, from the RBGE collections. I. Sampling

A rapid phylogeny of Marchantia, from the RBGE collections. II. Illuminating our sampling

Jul 062016
 

tempor

Vienna - the view from my 7th floor hotel room

Vienna in June – as seen from my hotel room

A couple of weeks ago I spent a few days in Vienna, my first visit in 11 years, when I was last over for the 2005 XVII International Botanical Congress. The location was practical – the hotel neatly nestled underneath a main road overpass, but extremely convenient from the airport, only a short train ride, and only minutes’ walk to the workshop venue, the Gregor Mendel Institute, where three days of talks and poster sessions on model early land plants were taking place. Arriving on the Tuesday evening, there was time to catch up with evolutionary biologist Dr Jill Harrison, a friend since our grad student days at RBGE, who has just moved her research group to the University of Bristol. The rest of my evening was spent fiddling with my slides for the talk I was giving the next morning.model system poster

Lecture theatre, Gregor Mendel Institute, with stairway scatter cushions

Lecture theatre, Gregor Mendel Institute, with stairway scatter cushions

Having attended a range of workshops in the past, nothing had quite prepared me for the scale of this one – with around 120 people registered, the large lecture theatre was packed, attendees spilling out to sit on cushions down the stairwells. Workshop organizers Professors Liam Dolan and Fred Berger opened the meeting, followed by a dazzling romp through Arabidopsis genomics from Professor Magnus Nordborg.

imagesTo introduce the next talk, I need a slight digression: If you are interested in land plant evolution, chances are you will have a copy of Dr Paul Kenrick and Peter Crane‘s The Origin and Early Diversification of Land Plants A Cladistic Study somewhere around your workspace. It was published in 1997, and my paperback copy is dog-eared and water-stained, having crossed the Atlantic more than once, and been lugged around various parts of the world in backpacks. My bookmark is still my deposit slip for the book: I ordered it in January 1998 from James Thin booksellers on South Bridge, Edinburgh, which obviously didn’t think local demand would be sufficient to keep copies in stock. (The book is still available to buy; sadly the bookshop went into administration in 2002.)

More than 18 years after buying and reading his book, this was the first time I’d actually heard Paul Kenrick speak, and it definitely goes down as one of the highlights of the meeting for me.  Clear, well paced and interesting, Paul led the audience through a concept of plant models that is very different to Arabidopsis-Physcomitrella-Marchantia.

Cupbarods full of liverworts in the RBGE Herbarium

Cupboards full of liverworts in the RBGE Herbarium

My own talk was a meander through the complex thalloid liverworts. The aim was to highlight the RBGE’s outstanding collection of dead complex thalloid plants, both as herbarium specimens and as silica dried tissue collections, and in addition, to point out some of the amazing non-Marchantia diversity within the group.

Some of the herbarium collections of Marchantia held in the RBGE herbarium

Some of the herbarium collections of Marchantia held in the RBGE herbarium

If I were composing my talk again today, it would be with an appreciation of two key facts about the audience that had not actually occured to me before the meeting. The first is that the other participants have an astounding understanding of their model plants’ form and function, at a level that far exceeds mine. The second is that an amazing resource of dead plants is not actually all that valuable to the evo-devo community, who are largely interested in what genes are expressed (transcriptomes, from RNA) and in what happens to plant growth when you change things – both of these require living material. Unfortunately, at RBGE we have extremely few bryophytes in the living collections – in fact, only two of which I am aware. We do incidentally have some rather spectacular quantities of Marchantia, although these have largely sprung up unrequested in an untended flowerbed….

A vast expanse of Marchantia polymorpha volunteers at RBGE

A vast expanse of Marchantia polymorpha volunteers at RBGE

Boxes of silica-dried liverworts in RBGE's tissue storage room

Boxes of silica-dried liverworts in RBGE’s tissue storage room

As the conference programme and abstracts are available online, however, I won’t go into any more detail about the talks, breaks, posters etc., but pick out a few key impressions. Overwhelmingly, mine are of a vast enthusiasm for experiment-driven natural history. Working out what things do, by trying to turn them off, and comparing that to what happens if you turn them on even brighter… the inevitable question if someone doesn’t mention this: “But have you tried overexpressing it?” Twisted curled balls of plant tissue, proliferating organs, and just general weirdness, all tied in to stories of How the Plant Became. Presentations of beautifully arranged slides, with professional quality illustrations. Internationality at all levels. And approachability.

An evening walk in Vienna, where we failed to find any Marchantia growing

An early evening walk in Vienna, where we failed to find any Marchantia growing

Sadly, I missed the last day of the meeting entirely, as I had another event scheduled – the Morag Alexander School of Dance annual show in Musselburgh. The show itself isn’t exactly a Once In A Lifetime experience – this one was the 7th annual dance show I’ve been to, but it was my daughter’s first ballet performance (for a few brief moments) on pointe. It did, however, mean missing what looked like a really enjoyable day of talks; in the light of short conversations earlier with both Dr Sebastian Schornack and Duke PhD student Jessica Nelson, theirs were two I was particularly disappointed to miss.

I am very grateful to Fred Berger and Liam Dolan for the invitation to come along and experience something that was, for me, just a little outside my regular molecular phylogeneticist comfort zone, but all the more interesting for that; and to Martina Gsar – the organization throughout was flawless. For the Physcomitrella and Marchantia evo-devo communities I have a short message: our plants may be mostly dead, and good for morphology and DNA only, but we are very happy to work with you in any areas that our fields overlap, and will welcome any of you who chose to visit us. Within the EU, funding to visit and work with natural history collections is available through the SYNTHESYS Access programme.

 

 

Oct 302015
 
Archegoniophores and antheridiophores of Marchantia; taken by Julia Bechteler

Archegoniophores and antheridiophores of Marchantia; photograph by Julia Bechteler

One of the earliest plastid genomes to be sequenced, in the late 1980s (Ohyama et al.), was that of Marchantia polymorpha, one of the commonest liverworts around town, and an increasingly widely used model organism for genetic research. The complete mitochondrial genome followed, with a key publication by Oda et al. in 1992. The research on both organellar genomes came from Kyoto University, Japan.

When we were generating a DNA sequence matrix for the complex thalloids, we also included GenBank sequences from the published genome sequences for both these organelles (mitochondrial loci nad1, nad5 and rps3 and plastid loci atpB, cpITS, psbA, psbT-psbH, rpoC1, rbcL and rps4), to see how they compared with sequences from the three subspecies of Marchantia polymorpha that are found in the United Kingdom (subspecies ruderalis is the weedy plant that is commonly found in paving cracks, flowerbeds and plant pots).

Marchantia phylogeny based on Villarreal et al. 2015, Fig. 2

Marchantia phylogeny based on Villarreal et al. 2015, Fig. 2

The results of the analyses (Villarreal et al. 2015) were rather unexpected: the plant from GenBank didn’t cluster with our Marchantia polymorpha accessions, but instead with a Marchantia paleacea accession from Mexico. Admittedly, both species form a clade, but there’s a convincing amount of genetic distance between them.

Marchantia polymorpha ventral scales, photograph by Des Callaghan Licensed under CC BY-SA 4.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Marchantia_polymorpha_scales.jpg#/media/File:Marchantia_polymorpha_scales.jpg

Marchantia polymorpha ventral scales; photograph by Des Callaghan. Licensed under CC BY-SA 4.0 via Wikimedia Commons

 

Helene Bischler-Causse (1989, 1993) separated Marchantia into sections based on morphological characters of the plants, placing Marchantia polymorpha in section Marchantia, and Marchantia paleacea alone in section Paleaceae, due in part to differences in the way the scales on the underside of the thallus are arranged, as well as spore morphology. Now it seems that the organelle genome sequences that have, for the last 1/4 century, been thought to be from Marchantia polymorpha, are in fact from this lesser known (but also widespread) species, Marchantia paleacea.

(Kijak et al.’s research at Mickiewicz University in Poland shows a similar picture; although their study is still unpublished, a poster from the group is available to download here.)

New Phytol title

Oct 292015
 
Complex thalloid phylogeny from Forrest et al. 2006

Complex thalloid phylogeny from Forrest et al. 2006

Rather a while ago, back in 2003, we started working on a phylogeny of the complex thalloid liverworts at the Royal Botanic Garden Edinburgh (as a Molecular Phylogenetics Project). We were beautifully placed to conduct the work, with taxonomist Dr David Long on the staff, and all the necessary molecular facilities in place. Plants were found, identified, extracted and sequenced, and a matrix started to develop for a set of five loci: the nuclear large ribosomal subunit, the mitochondrial gene nad5, and plastid loci rbcL, rps4 and psbA. The data were analysed in conjunction with sequences generated by Christine Davies, then a PhD student at Duke University, and by myself, as a postdoc, at Southern Illinois University, were presented at the International Botanical Congress in Vienna in 2005, and were published as part of a phylogeny of liverworts, in The Bryologist in 2006.

That same year, we made plans to expand the study, to tie in with a Tree of Life project on liverworts that was coordinated through Prof. Jon Shaw‘s lab at Duke University. Our aim was to sequence more plants for more loci (adding in mitochondrial loci nad1 and rps3 and plastid loci atpB, cpITS, psbT-psbN-psbH and rpoC1), to contribute to the larger project, but also to produce a stand-alone paper on the evolution of the complex thalloids. And this is where the continental drift, or the glaciers, come in. They are both things that can move faster than a scientific paper can be completed…

Fig. 2 inset: a. Riccia cavernosa (Des Callaghan), b. Cyathodium (Zhang Li), c. REboulia hemisphaerica (Zhang Li), d. Plagiochasma (Zhang Li), e. Lunularia cruciata (Des Callaghan), f. Marchantia (Zhang Li)

Fig. 2 inset: a. Riccia cavernosa (Des Callaghan), b. Cyathodium (Zhang Li), c. Reboulia hemisphaerica (Zhang Li), d. Plagiochasma (Zhang Li), e. Lunularia cruciata (Des Callaghan), f. Marchantia (Zhang Li) – from Villarreal et al. 2015, New Phytologist, Fig. 2

We did have data: I even talked about it at conferences – in 2007, at the sixth biennial conference of the Systematics Association in Edinburgh (Forrest, L.L., D.G. Long, A. Clark, M.L. Hollingsworth, Complex thalloids can be simple – unravelling the evolutionary history of the Marchantiopsida), and again at the Botany 2010 meeting in Rhode Island (Forrest, L.L., D.G. Long, M.L. Hollingsworth, J.C. Villarreal A., A. Clark, J. Tosh, P. Hollingsworth, Into the Tropics: a brief history of complex thalloid liverworts). However, there were holdups. Partly, we were waiting until we had complete genus-level sampling for the group, and a small number of very small genera were proving problematic to obtain. Indeed, we only got hold of adequate DNA for Monocarpus and Austroriella (both from Australia) in 2009, and Cronisia (Brasil), Aitchisoniella (China) and Stephensoniella (India) in 2011.

David Long and Juan Carlos Villarreal hunt for liverworts at Balerno Moss (2007) - photograph by Laura Forrest

David Long and Juan Carlos Villarreal hunt for liverworts at Balerno Moss (2007) – photograph by Laura Forrest

However, the main stumbling block to getting a phylogeny for the complex thalloid liverworts published was staff time, and in 2014 we were fortunate to obtain 6 months of funding from the Sibbald Trust to employ someone to complete the data sampling, conduct the analyses, and spearhead the paper-writing. Panamanian bryologist Dr Juan Carlos Villarreal joined us in January this year, from Munich Botanical Garden, where he had been working with Prof. Susanne Renner. And just yesterday, Wednesday the 28th October 2015, after 12 years in progress, our stand-alone paper on the phylogeny of the complex thalloids was finally published (Early View), in the journal New Phytologist.

New Phytol title

Jul 172015
 

Twenty-five participants from 13 countries have just attended a symposium on complex thalloid liverworts in Edinburgh #Marchantia2015. The meeting also included two teleconferences (from Australia, John Bowman, Monash University, and from the USA, Stuart McDaniel, University of Florida) and one recorded presentation (Péter Szövényi, University of Zurich).

#Marchantia2015 Complex Thalloid symposium at RBGE

#Marchantia2015 Complex Thalloid symposium at RBGE

Seated (left to right): Robbert Gradstein (MNHN Paris), Hanna Kijak (Adam Mickiewicz University), David Long (RBGE), Jeff Duckett (Natural History Museum London), Juan Carlos Villarreal (RBGE), Laura Forrest (RBGE)
Standing (left to right): Kumar Shantanu (University of Delhi), David Bell (University of British Columbia), Masaki Shimamura (Hiroshima University), Liam Dolan (University of Oxford), Neil Bell (RBGE), Halina Pietrykowska (Adam Mickiewicz University), Des Callaghan (bryophytesurveys.co.uk), Liz Kungu (RBGE), Izabela Sierocka (Adam Mickiewicz University), David Chamberlain (RBGE), Catherine Reeb (MNHN Paris), Sam Brockington (University of Cambridge), Aline Horwath (University of Cambridge), Bernardo Pollak (University of Cambridge), Silvia Pressel (Natural History Museum London).

Not shown are Alistair McCormick (University of Edinburgh), Cymon Cox (CCMAR), and Michelle Hollingsworth, Gunnar Ovstebo, Katie Emelianova and YunYu Chen (RBGE).

Following an introduction by the Regius Keeper, Simon Milne, the first day comprised of talks on the Diversity of complex thalloid liverworts (David G. Long), Amphitropical disjunctions in the complex thalloids  (Robbert Gradstein), 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), On Monocarpus (Monocarpaceae, Marchantiopsida), an isolated salt-pan complex thalloid liverwort (Laura L. Forrest, D.G. Long, D.C. Cargill, M.L. Hart, J. Milne, D.B. Schill, R.D. Seppelt, J.C. Villarreal), Sex chromosome evolution in haploid dioecy (e-talk) (Peter Szövényi, S.F. McDaniel, A. Payton, M. Ricca), Food- and water-conducting systems in complex thalloids with sexual reproduction thrown in (Jeff Duckett, S. Pressel) and Get off my turf! – Contrasting strategies for habitat specialisation by different bryophyte lifeforms (Aline Horwath). There were also two short presentations, one on the Journal of Bryology (Liz Kungu), and the other on NSF Genealogy of Life (GoLife) grant “Building a Comprehensive Evolutionary History of Flagellate Plants” (e-talk) (Stu McDaniel).

RBGE's Complex Thalloid symposium in full flow

RBGE’s Complex Thalloid symposium in full flow

On the second day of the meeting, talks comprised An update on the Marchantia genome (e-talk) (John Bowman, S. K. Floyd,T. Kochi, K.T. Yamato, K. Ishizaki, K. Berry, Jenkins, J. Schmutz), Evolution of sexual systems in complex thalloids (Masaki Shimamura), Development and evolution of the plant soil interface (Liam Dolan), Scratching the surface: The Marchantia Cuticle (Sam Brockington, S. Pressel, J. Duckett), An overview of Malagasy Marchantiidae (Catherine Reeb), Fungal associations in complex thalloids (Silvia Pressel, J.G. Duckett), 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), and 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).

 Thanks to RBGE and the Sibbald Trust, for logistic support and funding for the symposium.

Mar 022015
 
Complex thalloid liverwort Oxymitra, photographed by Chris Cargill

Complex thalloid liverwort Oxymitra, photographed by Chris Cargill

The complex thalloid liverworts, or Marchantiopsida, are one of the oldest land plant lineages, and contain a bewildering array of morphologies, ranging from comparatively simple plants like Blasia, Monoclea and Cyathodium to plants with highly modified sexual branches (‘female’ archegoniophores and ‘male’ antheridiophores) like Marchantia and Asterella. They grow predominantly in Mediterranean-type climates, although Marchantia and Lunularia will be familiar to gardeners as garden and greenhouse weeds. Many complex thalloid liverworts contain fungal endophytes, while, in common with some lichens, hornworts and cycads, Blasia has a symbiotic relationship with internalized colonies of photosynthetic blue-green algae Nostoc.

Blasia with flasks, photographed by David Long

Blasia with flasks, photographed by David Long

The Royal Botanic Garden Edinburgh (RBGE) has a long tradition of working on complex thalloid liverwort phylogenetics and systematics, including revisionary work on Asterella, Mannia, Sphaerocarpos and Cleveaceae.

Sphaerocarpos texanus photographed by David Long

Sphaerocarpos texanus photographed by David Long

In 2006, scientists at RBGE co-authored a multilocus phylogeny for liverworts, which included sampling of 28 complex thalloid genera (Clevea hyalina was included under the genus Athalamia) for five DNA loci. In the intervening years we have increased our sampling, both of DNA regions and of species. We are currently in the final stages of analysing a phylogeny for the group that includes complete genus-level sampling (with c.30% of the known species) for 11 loci, and also have species-level phylogenies of several genera in progress. The results of this have implications for when and how ‘complex thalloid’ morphology has evolved.

Asterella californica archegoniphores photographed by David Long

Asterella californica archegoniphores photographed by David Long

Because the dominant part of liverwort life-cycles is the (haploid) gametophyte, effects of genetic modifications of the plants can be rapidly observed and screened. Easy to grow, Marchantia is thus emerging as a popular model organism for synthetic biology.

Archegoniophores and antheridiophores of Marchantia; taken by Julia Bechteler

Archegoniophores and antheridiophores of Marchantia; taken by Julia Bechteler

In order to showcase Marchantia, but also to talk about the other weird and wonderful genera in this lineage, RBGE will hold a one- to two- day symposium for scientists with an interest in complex thalloid liverworts, with the aim of bringing together expertise on field and reproductive biology, development and ultrastructure, genomics and synthetic biology. This meeting will take place on 14th -15th July 2015 at the Royal Botanic Garden Edinburgh. The symposium will include a glasshouse tour and, if there is sufficient interest, a short laboratory session for anyone interested in looking at the complex thalloids we have growing at RBGE: currently Conocephalum, Lunularia, Marchantia and Plagiochasma. There is no registration cost involved.

Complex thalloid Plagiochasma photographed by Zhang Li

Complex thalloid Plagiochasma photographed by Zhang Li

If you like to present a talk or a poster, or just come along and join us, please contact us as soon as possible,

Juan Carlos Villarreal (j.villarreal@rbge.ac.uk), Laura Forrest and David Long.

Complex thalloid liverwort Monocarpus sphaerocarpos, photographed by Pina Milne

Complex thalloid liverwort Monocarpus sphaerocarpos, photographed by Pina Milne