Message - 7th IAL Symposium

The 7 th International Association for Lichenology Symposium 2012
(1I-O5) Submission ID: IAL0159-00002
PYROSEQUENCING REVEALS PREVIOUSLY UNKNOWN PHYLOGENETIC, METABOLIC AND
ECOLOGICAL COMPLEXITY WITHIN THE LICHEN MICROBIOME
Hodkinson B.P. 1 , Gottel N.R. 2 , Schadt C.W. 2 , Lutzoni F. 3
1 International Plant Science Center, New York Botanical Garden, Bronx, New York, United States
2 Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
3 Biology Department, Duke University, Durham, North Carolina, United States
Although common knowledge dictates that a lichen is formed solely by a fungus (mycobiont) that
develops a symbiotic relationship with an alga and/or cyanobacterium (photobiont), lichen-associated non-photobiont
bacteria are increasingly regarded as significant players in the ecology and physiology of the lichen
microbiome. For this study, 454 pyrosequencing and Sanger sequencing of cloned amplicons were conducted
on lichen-associated bacteria to determine the ecological factors influencing their community composition and
the metabolic functions that they perform. The 16S (SSU) rRNA gene of Bacteria was sequenced from lichen
samples representing 24 genera collected from tropical to arctic environments. Comparative analyses of these
sequence libraries indicate that bacterial community differences are correlated with a variety of factors, the most
notable of which is photobiont-type. Metatranscriptomic libraries were made for lichens containing the two major
photobiont-types (green algae [Cladonia grayi] and cyanobacteria [Peltigera praetextata]). These data reveal
the diversity of functional genes in each sample, and demonstrate the fundamental differences between lichens
with different types of photobionts in terms of basic carbon and nitrogen processing. Based on these functional
analyses and phylogenetic results, differences in carbon and nitrogen cycling in lichens are proposed as major
ecological drivers of differentiation between bacterial communities within the lichen microbiome, with secondary
compounds as an alternative factor than can drastically shift the composition of bacterial communities in
lichens.
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