• Orchids are highly dependent on their mycorrhizal fungal partners for nutrient supply, especially during early developmental stages. In addition to organic carbon, nitrogen (N) is likely a major nutrient transferred to the plant because orchid tissues are highly N-enriched. We know almost nothing on the N form preferentially transferred to the plant and on the key molecular determinants required for N uptake and transfer. • We identified, in the genome of the orchid mycorrhizal fungus Tulasnella calospora, two functional ammonium transporters and several amino acid transporters but no evidence of a nitrate assimilation system, in agreement with N preference of the free living mycelium grown on different N sources. • Differential expression in symbiosis of a repertoire of fungal and plant genes involved in transport and metabolism of N compounds suggests that organic N may be the main form transferred to the orchid host and that ammonium is taken up by the intracellular fungus from the apoplatic symbiotic interface. • This is the first study addressing the genetic determinants of N uptake and transport in orchid mycorrhiza, and provides a model for nutrient exchanges at the symbiotic interface, which may guide future experiments.

Fungal and plant gene expression in the Tulasnella calospora - Serapias vomeracea symbiosis provides clues on N pathways in orchid mycorrhizas

FOCHI, VALERIA;CHITARRA, WALTER;VOYRON, Samuele;GIRLANDA, Mariangela;BALESTRINI, RAFFAELLA;PEROTTO, Silvia
Last
2017-01-01

Abstract

• Orchids are highly dependent on their mycorrhizal fungal partners for nutrient supply, especially during early developmental stages. In addition to organic carbon, nitrogen (N) is likely a major nutrient transferred to the plant because orchid tissues are highly N-enriched. We know almost nothing on the N form preferentially transferred to the plant and on the key molecular determinants required for N uptake and transfer. • We identified, in the genome of the orchid mycorrhizal fungus Tulasnella calospora, two functional ammonium transporters and several amino acid transporters but no evidence of a nitrate assimilation system, in agreement with N preference of the free living mycelium grown on different N sources. • Differential expression in symbiosis of a repertoire of fungal and plant genes involved in transport and metabolism of N compounds suggests that organic N may be the main form transferred to the orchid host and that ammonium is taken up by the intracellular fungus from the apoplatic symbiotic interface. • This is the first study addressing the genetic determinants of N uptake and transport in orchid mycorrhiza, and provides a model for nutrient exchanges at the symbiotic interface, which may guide future experiments.
2017
213
365
379
orchid mycorrhiza, Tulasnella, Serapias, nitrogen
Valeria, Fochi; Walter, Chitarra; Annegret, Kohler; Samuele, Voyron; Vasanth, R. Singan; Erika, Lindquist; Kerrie, Barry; Mariangela, Girlanda; Igor, V. Grigoriev; Francis, Martin; Raffaella, Balestrini; Silvia, Perotto
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1597266
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