A portion of our research focuses on the Arbuscular Mycorrhizal Fungi (AMF). AMF represent an ecologically relevant group of "ancient asexuals" that form widespread symbioses with the roots of most land plants. This symbiosis has been found to improve the root uptake of nutrients from the soil, and results in a higher fitness for the host. For this reason, AMF are often used in organic practices (i.e. organic farming, plant nurseries) and phytoremediation programs.
Besides their tremendous ecological importance, AMF are also characterized by very unique cellular features. For example, each AMF mycelium can harbor hundreds of nuclei, all of which coexist within one single cytoplasm (i.e. coenocyte). What is the biological relevance of this atypical genetic system (i.e. is it helpful for the fungus, or the plant?). How does genetic diversity originates, and how is it maintained within AMF individuals and populations in the absence of gene exchange ? (i.e. is it intragenomic or inter-nuclear, and which mechanisms create genetic diversity in AMF?).
The ultimate goal of this research is to allow the production of AMF strains that lead to better plant growth. To reach this goal, our team aims to identify the molecular and genetic mechanism involved in partner recognition in this fungal group. This is done by cultivating a large number of AMF species and isolates in the lab, and by exploring their phenotype, interactions and genetic organization under different growth conditions.
- For a review of our work on AMF genetics and previous knowledge on the matter: Corradi and Brachmann 2017, Trends in Plant Science
- First evidence of a mating-type locus and hybridization in AMF: Ropars et al 2016, Nature Microbiology
- Discovery of peculiar gene expansions in important Plant-symbionts: Riley R. et al. 2014, New Phytologist
- Unusual Mitochondrial Structure in the AMF Gigaspora margarita: Pelin A. et al. 2012. New Phytologist
Microsporidian Parasites and Allies
Our lab also specializes in the analysis of a ubiquitous group of obligate intracellular parasites, called Microsporidia. These organisms are know to infect virtually all animals, including humans and many species of economic importance, such as salmon, honeybees or the silkworm. In humans, microsporidiosis (the disease associated with microsporidia infections) is usually benign, but it can also lead to severe symptoms including chronic diarrhoea and encephalitis; particularly in immuno-compromised patients.
The unique intracellular lifestyle of microsporidia is reflected in the size and content of their genomes, which are always gene poor and, in some cases, can be extremely small and compact (i.e. the smallest known is only 2.3Mb!). Our lab has been involved in genome sequencing projects of many species in this group, as a mean to better understand the biology of these important pathogens. Our research resulted in the first population genomic analysis of microsporidians (Pelin et al. 2015, Environmental Microbiology), and now develops experimental population analyses of these parasites. We put particular attention on microsporidian species of veterinary (Encephalitozoon sp., a common vertebrate pathogen), scientific (Pseudoloma neurophila; a pathogen of the model Zebrafish) and economic importance (Nosema ceranae, a relevant honeybee parasite).
More recently, the microsporidian Nosema ceranae has hit the spotlight for their association with global declines in honeybee-colonies. Our lab has revealed this parasite has spread globally through human intervention, most likely via international commerce of beehives. We also showed that the N. ceranae genome is polyploidy, and atypical genome organization that causes high genetic diversity in global populations of this parasite. Research Highlights:
- For a review on microsporidian genomics and evolution: Corradi N. 2015. Annual Review of Microbiology
- Detection of atypical nuclear complexity and dispersion patterns in pathogens of honey-bees: Pelin A. et. al. 2015. Environmental Microbiology.
- Discovery of unusual gene-acquisitions in vertebrate parasites: Selman M. et al. 2011. Current Biology.