Phylogenetically Mapping Liverwort-Fungal Associations

Jessica NelsonDuke University

Background: Organisms

http://greatneck.k12.ny.us/GNPS/SHS/dept/science/krauz/bio_h/images/29_07PlantPhylogeny_L.jpg

Background: Organisms

• Fungi live inside liverworts as endophytes

• not much is known about these fungal communities or their relationship to the plants– Mutual- mycorrhizae?

Stress resistance?Duckett, Jeffrey G. and David J. Read. (1995). Ericoid mycorrhizas and rhizoid-ascomycete associations in liverworts share the same mycobiont: isolation of the partners and resynthesis of the associations in vitro. New Phytologist 129: 439-447.

Background: Research to Date

• Morphological- light and electron microscopy

• Very low level of taxonomic detail• Trees for fungus with liverworts

mapped on• Endophyte vs. symbiont research

“islands”• Scattered genetic studies

– Mostly by the same few researchers– Data not well curated

• Focus on particular fungal groups– Specific primers– e.g. Tulasnella, Xylaria, Sebacina

Kottke, Ingrid and Martin Nebel. (2005). The evolution of mycorrhiza-like associations in liverworts: an update. New Phytologist 167(2): 330-334.

Study Goals

• Map fungal associates onto liverwort tree in more detail

• Compare phylogenies of the liverworts and fungi studied so far

• Review previous research in the field and present in a new, useful way to suggest further investigation

Methods

• Literature Review– Collected papers and coded their information into a single

database– Chose liverwort species for which at least one fungal associate

was known to genus and those with “no fungal association”• Genetic Data

– Liverworts• species with information in the literature + some to fill in the major

clades• Liverwort Tree of Life project

– Fungi• GenBank records from papers reviewed• Assembling the Fungal Tree of Life database to fill in gaps

Methods• 34 Species of liverwort, 3 genes

– psbT: plastid photosystem protein, coding and noncoding– rps3: mitochondrial, coding– rps4: plastid, coding

• 27 Fungal sequences for nucLSU: 16 isolated from liverworts, 11 identified species to fill out

• Alignment using MAFFT and MUSCLE to start and manual adjustments in Mesquite and Phyde

• Maximum parsimony (PAUP), Maximum Likelihood (GARLI), and Bayesian (MrBayes)

• Models chosen by running jmodeltest for non-protein coding genes (nucLSU, psbT)

• Models chosen with partition finder for coding genes and concatenated data sets

• Tracer and AWTY used to check Bayesian runs

Results: Maximum Parsimony

Results: Bayesian

Concatenated

rps3

Results: Maximum Likelihood• More ancient

lineages of fungi and liverworts found together

• No clear clade of non-fungal liverworts

• Thalloid liverworts with same fungal species that are endomycorrhizal in vascular plants

• Same genera of fungi across liverwort clades– Some partitioning by

genus in Basidiomycetes?

– Sampling biases– More diversity there

Results: Maximum Likelihood

• Species isolated from different liverworts similar- more data• Suggestion of phylogenetic partitioning by ecosystem roles

– E.g. T. violea saprobe vs. the sampled endophytes vs. T. asymmetrica orchid mycorrhizal

Future Directions

• Taxonomically broader sampling of fungi• Complete, controlled data sets of specific

liverwort-fungal associations• Are the associations structured more by

phylogenetic relationships or by ecological roles?

• Dating symbiosis developments? • Investigation of function

Questions?