The genome sequence of the symbiotic fungus Laccaria bicolor

F. Martin (1), J. Wuyts (1,2), I. Grigoriev (3), P. Rouzé (2), S. Rombauts (2), A. Aerts (3), Asaf Salamov (3), D. Cohen (1), P.-E. Courty (1), C. Delaruelle (1), A. Deveau (1), F. Duchaussoy (1), S. Duplessis (1), J. Labbe (1), F. Le Tacon (1), A. Kohler (1), M. Peter (1), P. Bolkstein (3), J.-C. Detter (3), E. Lindquist (3), H. J. Shapiro (3), P. M. Richardson (3), Y. van de Peer (2), M. Muratet (4), G. Podila (4), JGI Production Sequencing Staff (3) & Laccaria Annotation Network

(1) UMR INRA/UHP 1136, Interactions Arbres/Microorganismes, INRA-Nancy, 54280 Champenoux

(2) Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, Ghent University B-9052 Gent, BELGIUM

(3) US DOE Joint Genome Institute, Walnut Creek, CA 94598? USA

(4) Department of Biological Sciences, University of Alabama, Huntsville, USA

Tree species dominating forest ecosystems in boreal, temperate and montane regions develop symbiotic associations with soil fungi, so-called ectomycorrhizas. Ectomycorrhizas have a beneficial impact on plant growth in natural and agroforestry ecosystems. Central to the success of these mutualistic symbioses is the exchange of nutrients between the partners. To elucidate the genetic basis of this ecologically important behavior, the US Department of Energy Joint Genome Institute (JGI) has sequenced the 65-megabase genome of the ectomycorrhizal basidiomycete Laccaria bicolor (Agaricales, Tricholomataceae) to high draft using a whole genome shotgun method. This is the first symbiotic fungus genome to be sequenced. It contains about 20,000 intron-rich gene structures-more than twice as many as Neurospora crassa and Phanerochaete chrysosporium. Analysis of the gene set yields insights into unexpected aspects of Laccaria biology including the identification of genes potentially associated with wood decay. This fungus also possesses an expanded family of G-protein-coupled receptors, several virulence-associated genes and large suites of enzymes involved in secondary metabolism. About 40,000 ESTs from various cDNA libraries have been sequenced and the tentative consensi have been compared to gene models. Alternatively spliced and altered transcripts are abundant. The genome is rich in transposons belonging to various class I and II families. Comparison of the genomes of the different pathogenic and saprobic fungi with the Laccaria genome will be of interest to a wide range of genome and evolutionary scientists. It will provide critical insights into the genetic makeup of plant-fungus interactions.

Acknowledgements: This project is a collaborative effort involving: DOE Joint Genome Institute (JGI, coordinator: P Richardson), INRA-Nancy (UMR IaM, F Martin et al.), University of Alabama-Huntsville (Department of Biological Sciences, G Podila et al.), Gent University (Bioinformatics & Evolutionary Genomics Division, P Rouzé et al.) and DOE Oak Ridge National Laboratory (Dr. J Tuskan & Dr. S DiFazio).