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Two differentially regulated phosphate transporters from the symbiotic fungus Hebeloma cylindrosporum and phosphorus acquisition by ectomycorrhizal Pinus pinaster
Author(s) -
Tatry MarieViolaine,
El Kassis Elie,
Lambilliotte Raphaël,
Corratgé Claire,
Van Aarle Ingrid,
Amenc Laurie K.,
Alary Rémi,
Zimmermann Sabine,
Sentenac Hervé,
Plassard Claude
Publication year - 2009
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2008.03749.x
Subject(s) - biology , pinus pinaster , mycorrhiza , phosphate , ectomycorrhizae , botany , symbiosis , endodermis , ectomycorrhiza , fungus , transporter , phosphorus , biochemistry , gene , chemistry , bacteria , genetics , organic chemistry
Summary Ectomycorrhizal symbiosis markedly improves plant phosphate uptake, but the molecular mechanisms underlying this benefit are still poorly understood. We identified two ESTs in a cDNA library prepared from the ectomycorrhizal basidiomycete Hebeloma cylindrosporum with significant similarities to phosphate transporters from the endomycorrhizal fungus Glomus versiforme and from non‐mycorrhizal fungi. The full‐length cDNAs corresponding to these two ESTs complemented a yeast phosphate transport mutant (Δ pho84 ). Measurements of 33 P‐phosphate influx into yeast expressing either cDNA demonstrated that the encoded proteins, named HcPT1 and HcPT2, were able to mediate Pi:H + symport with different affinities for Pi ( K m values of 55 and 4 μ m , respectively). Real‐time RT‐PCR showed that Pi starvation increased the levels of HcPT1 transcripts in H. cylindrosporum hyphae grown in pure culture. Transcript levels of HcPT2 were less dependent on Pi availability. The two transporters were expressed in H. cylindrosporum associated with its natural host plant, Pinus pinaster , grown under low or high P conditions. The presence of ectomycorrhizae increased net Pi uptake rates into intact Pinus pinaster roots at low or high soil P levels. The expression patterns of HcPT1 and HcPT2 indicate that the two fungal phosphate transporters may be involved in uptake of phosphate from the soil solution under the two soil P availability conditions used.