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Gigaspora rosea DAOM197757
Top. Spores with visible lipid droplets (bar 100 µm). Bottom. Coils and arbuscules observed in cortical root cells of Brachypodium distachyon (bar 50 µm)
Image credit : Nianwu TANG and Christophe ROUX

Arbuscular mycorrhizal symbiosis between plants and Glomeromycota, a phylum of early diverging Fungi. is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. 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 – ubiquist and abundant obligate biotrophs associated with 80% of plants - have long fascinated evolutionary biologists. 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. In 2013, we have published the first genome of an AM fungus: Rhizophagus irregularis strain DAOM197198 (Glomerales). A unique haploid genome was identified in this strain with a repertoire of 28,232 genes. Glomeromycota are formed by distinct clades. Although AMF species have a very broad host spectrum, they differ by their fitness to plant genotypes and environment.

Gigaspora rosea DAOM 194757

Species from the family of Gigasporaceae (Order Diversipsorales) form large hyphae and big spores (>200µm). According to plant hosts, Gigaspora spp can develop different types of intracellular structures, i.e. arbuscules and coils. Gigaspora rosea DAOM194757 can be easily cultivated on entire plant in pots and in vitro on root organ culture. Due to their ability to form long germinating hyphae, it was used to characterize the response to strigolactones (an early plant symbiotic signals) and the synthesis of lipo-chito-oligosaccharides (fungal symbiotic signals). G. rosea is mainly found in non perturbed soil. Genome comparison with R. irregularis and other phylogenetically distinct species will give clues in deciphering shared and specific features involved in the symbiotic biology of AM fungi.

Collaborators:

Biological material production: Dr Sébastien Roy and Julie Viala (Agronutrition- Labège, France) , Dr Nianwu Tang (LRSV-Toulouse)
RNAseq material and analyses: Dr Nianwu Tang and Pr Christophe Roux (LRSV-Toulouse)
Genome assembly: Hélène San Clemente (LRSV-Toulouse) and Dr Claude Murat (INRA IAM-Nancy)
Annotation: Emmanuelle Morin (INRA IAM-Nancy)
Coordinators: Dr Francis Martin (INRA IAM-Nancy) and Pr Christophe Roux (LRSV-Toulouse)

Genome Reference(s)