Journal Article

Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis

Charron, Philippe, Hijri, Mohamed, Koul, Raman, Gilbert, Luz B., Requena, Natalia, Symeonidi, Aikaterini, Frey, Nicolas Frei dit, Ndikumana, Steve, Martin, Francis, Kuo, Alan, Paszkowski, Uta, Herr, Joshua R., Henrissat, Bernard, Gianinazzi-Pearson, Vivienne, Shapiro, Harris, Young, Peter W., Malbreil, Mathilde, Clemente, Hélène San, Riley, Rohan, Kawaguchi, Masayoshi, Morin, Emmanuelle, Sanders, Ian R., Rensing, Stefan A., van Tuinen, Diederik, Krajinski, Franziska, Shachar-Hill, Yair Y., Saito, Katsuharu, Handa, Yoshihiro, Kohler, Annegret, Tuskan, Gerald A., Masclaux, Frederic G., Tisserant, Emilie, Lammers, Peter J., Bécard, Guillaume, Balestrini, Raffaella, Pagni, Marco, Murat, Claude, Rosikiewicz, Pawel, Petitpierre, Denis, Grigoriev, Igor V., Duensing, Nina, Corradi, Nicolas, Bonfante, Paola, Roux, Christophe

2013

Overview

The mutualistic symbiosis involving Glomeromycota, a distinctive phylum of early diverging Fungi, is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. These arbuscular mycorrhizal fungi (AMF) perform vital functions in the phosphorus cycle that are fundamental to sustainable crop plant productivity. The unusual biological features of AMF have long fascinated evolutionary biologists. The coenocytic hyphae host a community of hundreds of nuclei and reproduce clonally through large multinucleated spores. It has been suggested that the AMF maintain a stable assemblage of several different genomes during the life cycle, but this genomic organization has been questioned. Here we introduce the 153-Mb haploid genome of Rhizophagus irregularis and its repertoire of 28,232 genes. The observed low level of genome polymorphism (0.43 SNP per kb) is not consistent with the occurrence of multiple, highly diverged genomes. The expansion of mating-related genes suggests the existence of cryptic sex-related processes. A comparison of gene categories confirms that R. irregularis is close to the Mucoromycotina. The AMF obligate biotrophy is not explained by genome erosion or any related loss of metabolic complexity in central metabolism, but is marked by a lack of genes encoding plant cell wall-degrading enzymes and of genes involved in toxin and thiamine synthesis. A battery of mycorrhiza-induced secreted proteins is expressed in symbiotic tissues. The present comprehensive repertoire of R. irregularis genes provides a basis for future research on symbiosis-related mechanisms in Glomeromycota.

• Publisher: National Academy of Sciences,NATIONAL ACADEMY OF SCIENCES,National Acad Sciences
• Subject: Base Sequence / Biological and medical sciences / Biological evolution / Biological Sciences / biologists / crops / embryophytes / Enzymes / evolution / Evolution, Molecular / Evolutionary biology / Fundamental and applied biological sciences. Psychology / Fungal spores / Fungi / Genes / Genetics of eukaryotes. Biological and molecular evolution / Genome, Fungal - genetics / Genomes / Genomics / Glomeromycota / Glomeromycota - genetics / haploidy / hyphae / Life Sciences / Metabolism / Molecular Sequence Data / Mucoromycotina / Mycorrhizae - genetics / Mycorrhizal fungi / nucleotide sequences / Paleozoic / Parasitism and symbiosis / phosphorus / Phosphorus cycle / Plant physiology and development / Plants / Plants - microbiology / Polymorphism / protein synthesis / Proteins / Rhizophagus / Rhizophagus irregularis / Sequence Analysis, DNA / single nucleotide polymorphism / spores / Sustainable agriculture / Symbiosis / Symbiosis - genetics / thiamin / tissues / Toxins