Sugar transport in abuscular mycorrhiza
Résumé
Arbuscular mycorrhizal fungi (AMF) are ubiquitous soil microorganisms that live in symbiotic association with plant roots. This mutualistic association is characterized by trophic exchanges between the two partners. The fungi supply the autotrophic host with nutrient and thereby enhancing plant growth. In return, the plant provides sugar photosynthates to the heterotrophic symbiont. The importance of sugar transfer as the sole carbon source for AMF is emphasized by the fact that the fungus is unable to grow and complete their life cycle in absence of their host plant.
This study focuses on sugar transporter at both plant and fungal levels and at the symbiotic interface to better understand biotropohic exchange systems. We identified sugar transporter genes in the model leguminous species Medicago truncatula and focused on the characterization of sucrose transport proteins (MtSUTs). These transporters are involved in long distance transport of sucrose from source leaves to fungal sink. On the fungal side, the first hexose transporter (GpMST1) from Geosiphon pyriformis, a glomeromycotan species related to the model AMF Glomus intraradices, has been characterized. The identification and functional analysis of such transporters will provide key information on mechanisms that underlie carbon partitioning within and between these symbionts.