phylogenetically mapping liverwort-fungal associations jessica nelson duke university jessica nelson...
TRANSCRIPT
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?