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 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