Phosphorus Transport in Mycorrhiza: How Far Are We?

Mycorrhizal fungi considerably improve plant nutrition and help them to cope with changing environments. Particularly, these fungi express proteins to transfer inorganic phosphate (Pi) from the soil to colonized roots through symbiotic interfaces. The mechanisms involved in Pi transfer from fungal to plant cells are still largely unknown. Here, we discuss the recent progress made on the description of these mechanisms and we propose the most promising hypotheses and alternative mechanisms for this process. Specifically, we present a phylogenetic survey of candidate Pi transporters of mycorrhizal fungi that might ensure Pi unload into the symbiotic interfaces. Gathering additional knowledge on mycorrhizal Pi transport will improve the Pi-useefficiency in agroecological systems and will guide towards addressing future research challenges.