Phosphorus Transport in Mycorrhiza: How Far Are We?

• Published in: Trends in plant science 2019-09, Vol.24 (9), p.794-801
• Main Authors: Plassard, Claude, Becquer, Adeline, Garcia, Kevin
• Format: Article
• Language: English
• Subjects: arbuscular mycorrhizal symbiosis; Changing environments; ectomycorrhizal symbiosis; Fungi; H+:Pi transporter; inorganic phosphate; Interfaces; Life Sciences; Mycorrhizae; Nutrition; organic phosphate; Phosphate Transport Proteins; Phosphorus; Phylogeny; Pi:Na+ transporter; Plant cells; Plant nutrition; Plant Roots; Symbiosis; Transport; Vegetal Biology
• ISSN: 1360-1385; 1878-4372
• DOI: 10.1016/j.tplants.2019.06.004

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. The acquisition of phosphorus by plants is often mediated by soil microbes colonizing the roots, particularly mycorrhizal fungi.Key molecular mechanisms involved in the transport of phosphorus from the soil to mycorrhizal fungi have been revealed recently. However, the release of phosphorus towards colonized roots is still understudied, even if a recent report highlighted the possible involvement of fungal H+:Pi transporters.Based on a survey of fungal transport proteins, others mechanisms possibly ensuring phosphorus efflux in mycorrhizas must coexist besides H+:Pi transporters. These include the putative involvement of Pi :Na+, low-affinity inorganic phosphate, and organic phosphate transporters.Unravelling the fungal phosphorus transportome will allow a better use of plant–fungus symbioses for the improvement of plant nutrition in cropping systems.