Message - 7th IAL Symposium

Lichen: from genome to ecosystem in a changing world
1B-P
(1B-P3) Submission ID: IAL0241-00002
ANNOTATING BIOSYNTHETIC GENE CLUSTERS IN THE CLADONIA GRAYI GENOME
Dal Grande F. 1 , Bode H. B. 2 , Armaleo D. 3 , Slot J. C. 4 , Schmitt I. 1
1 Senckenberg Gesellschaft Fuer Naturforschung, Biodiversity and Climate Research Centre, Frankfurt Am Main, Germany
2 Department of Biological Sciences, Goethe Universität Frankfurt, Frankfurt Am Main, Germany
3 Department of Biology, Duke University, Durham, United States
4 Department of Biology, Clark University, Worcester, United States
We screened the genome sequence of Cladonia grayi for conserved protein domains of biosynthetic
genes coding secondary metabolites. Here, we report the number and organization of polyketide synthase and
nonribosomal peptide synthetase gene clusters.
(1B-P4) Submission ID: IAL0246-00001
TISSUE- SPECIFIC GENE EXPRESSION AND DNA CYTOSINE METHYLATION
IN THE LICHEN PELTIGERA MEMBRANACEA
Manoharan S. S. 1 , Snæbjarnarson V. 1 , Miao V. 2 , Jonsson Z. O. 1 , Andrésson O. 1
1 Department of Life and Environmental Sciences, University of Iceland, Reykjavik, Iceland
2 Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
DNA cytosine methylation (5mC) plays an essential role in the normal development of mammals and
plants and is associated with various biological processes, such as silencing of transposons, regulation of gene
expression during development and cell differentiation. In fungi, DNA methylation has been viewed as primarily a
mechanism of genome defense (e.g in Neurospora crassa), but has also been proposed to modulate transcriptional
activity (e.g Candida albicans). We explored the role of methylation in development of the mycobiont of the
lichen, Peltigera membranacea, by identifying genes involved in methylation in a genome sequence assembly,
by analysing llumina-sequencing data from bisulfite-treated total metagenomic DNA of apothecia (non-symbiotic
tissue) and thalli including both mycobiont and symbiotic photobionts, and correlating the results with transcriptomic
data obtained by llumina RNA-Seq. Putative homologs to most N. crassa genes involved in DNA methylation
were found, including hpo, dim-2, and the members encoding a DCDC complex (dim-5, dim-7, dim-9, as
well as cul4, ddb1 and their presumptive associated factors). Genes of the DMM complex that prevent spreading
of methylation from transposons to nearby genes were also identified. Single-base resolution mapping in P.
membranacea revealed some of the same distributional features as N. crassa, such as the occurrence of 5mC
in all sequence contexts, and heavy methylation of transposons and repeat elements. However, a substantial
fraction of the genes are also methylated in the transcribed regions (body) as in C. albicans, and in short regions
that are depleted of G on one strand. Analysis of the RNA–Seq reads using Cufflink software revealed gene
expression levels and splicing isoforms. A large number of genes showed tissue-specific gene expression and
were not methylated, e.g. one of two ammonium transporter genes was strongly expressed in thalli, the other
only in apothecia. lec1, encoding a lectin possibly involved in mycobiont-photobiont interaction was more highly
expressed in thalli than in non-symbiotic tissues. The observation to date suggests that while one role of methylation
in P. membranacea may be to silence transposons, additional functions, particularly with relation to gene
body methylation, will be elucidated.
92