The Hebeloma cylindrosporum HcPT2 Pi transporter plays a key role in ectomycorrhizal symbiosis

Through a mutualistic relationship with woody plant roots, ectomycorrhizal fungi provide growth-limiting nutrients, including inorganic phosphate (Pi), to their host. Reciprocal trades occur at the Hartig net, which is the symbiotic interface of ectomycorrhizas where the two partners are symplasmica...

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Bibliographic Details
Published in:The New phytologist 2018-12, Vol.220 (4), p.1185-1199
Main Authors: Becquer, Adeline, Garcia, Kevin, Amenc, Laurie, Rivard, Camille, Doré, Jeanne, Trives‐Segura, Carlos, Szponarski, Wojciech, Russet, Sylvie, Baeza, Yoan, Lassalle‐Kaiser, Benedikt, Gay, Gilles, Zimmermann, Sabine Dagmar, Plassard, Claude
Format: Article
Language:English
Subjects:
32P labeling
Cylinders
ectomycorrhizal (ECM) fungus
Ectomycorrhizas
Efflux
Fluorescence
Fungi
Gene mapping
Hartig net
Host plants
Hyphae
Life Sciences
Limiting factors
Limiting nutrients
Microscopy
Mineral nutrients
Nutrients
overexpression
phosphate transporter
Phosphates
Pine trees
Pinus pinaster
Plant physiology
Plant roots
Proteins
RNA interference
Roots
Symbionts
Symbiosis
Vegetal Biology
X‐ray fluorescence mapping
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Summary:Through a mutualistic relationship with woody plant roots, ectomycorrhizal fungi provide growth-limiting nutrients, including inorganic phosphate (Pi), to their host. Reciprocal trades occur at the Hartig net, which is the symbiotic interface of ectomycorrhizas where the two partners are symplasmically isolated. Fungal Pi must be exported to the symbiotic interface, but the proteins facilitating this transfer are unknown. In the present study, we combined transcriptomic, microscopy, whole plant physiology, Xray fluorescence mapping, 32P labeling and fungal genetic approaches to unravel the role of HcPT2, a fungal Pi transporter, during the Hebeloma cylindrosporum–Pinus pinaster ectomycorrhizal association. We localized HcPT2 in the extra-radical hyphae and the Hartig net and demonstrated its determinant role for both the establishment of ectomycorrhizas and Pi allocation towards P. pinaster. We showed that the host plant induces HcPT2 expression and that the artificial overexpression of HcPT2 is sufficient to significantly enhance Pi export towards the central cylinder. Together, our results reveal that HcPT2 plays an important role in ectomycorrhizal symbiosis, affecting both Pi influx in the mycelium and efflux towards roots under the control of P. pinaster.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.15281