Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Genes coding for proteins involved in nitrogen and phosphate metabolism (amino acid permease and phosphate transporter) in Glomus mosseae

In the mutualistic AM symbiosis the plant supplies the fungus with carbon while the fungus assists the plant in its uptake of phosphate and other mineral nutrient from the soil. Genes involved in nitrogen and phosphate metabolism (amino acid permease and phosphate transporter) were investigated in the AM fungus Glomus mosseae.

G. mosseae amino acid permease:
A combination of PCR with degenerated oligonucleotides and 5’ and 3’ RACE-PCR assays led to the identification of a cDNA sequence (GmosAAP1) coding for a protein similar to previously described amino acid permeases. GmosAAP1 consists of 572 amino acids, a molecular mass of 61.7kDa and twelve putative transmembrane domains; this structure is in agreement with that of other fungal and yeast amino acid permeases. Gene expression analyses, performed by RT-PCR assays, demonstrated that GmosAAP1 was exclusively expressed in extraradical mycelium. Real-Time experiments indicated that GmosAAP1 expression was modulated by different nitrogen sources.

G. mosseae phosphate transporter:
By means of degenerate primers and RACE experiments we identified a 1120 bp cDNA sequence (GmosPT) showing the highest similarity with G. intraradices phosphate transporters (E value=e-177, identity 72%, similarity 85%). The sequence contains the complete 3’ end and corresponds to 80% of the expected full length protein (420 over 520 aminoacids). A phylogenetic analysis showed that GmosPT protein groups together with the other two phosphate transporters isolated from AM fungi, close to all of the fungal transporters and separated from the plant P transporter sequences. GmosPT expression was monitored by RT-PCR assays. GmosPT expression in extraradical mycelium responded to external concentration of phosphate: the transcript resulted more abundant in external hyphae exposed to 35 micromolar Na2HPO4 than in external hyphae treated with 3.5 millimolar Na2HPO4.

More information on the Genomyca -project can be found at: http://www.dijon.inra.fr/genomyca/

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