title: Metabolomics Suggests That Soil Inoculation with Arbuscular Mycorrhizal Fungi Decreased Free Amino Acid Content in Roots of Durum Wheat Grown under N-Limited, P-Rich Field Conditions.
abstract: Arbuscular mycorrhizal fungi (AMF) have a major impact on plant nutrition, defence against pathogens, a plant's reaction to stressful environments, soil fertility, and a plant's relationship with other microorganisms. Such effects imply a broad reprogramming of the plant's metabolic activity. However, little information is available regarding the role of AMF and their relation to other soil plant growth-promoting microorganisms in the plant metabolome, especially under realistic field conditions. In the present experiment, we evaluated the effects of inoculation with AMF, either alone or in combination with plant growth-promoting rhizobacteria (PGPR), on the metabolome and changes in metabolic pathways in the roots of durum wheat (Triticum durum Desf.) grown under N-limited agronomic conditions in a P-rich environment. These two treatments were compared to infection by the natural AMF population (NAT). Soil inoculation with AMF almost doubled wheat root colonization by AMF and decreased the root concentrations of most compounds in all metabolic pathways, especially amino acids (AA) and saturated fatty acids, whereas inoculation with AMF+PGPR increased the concentrations of such compounds compared to inoculation with AMF alone. Enrichment metabolomics analyses showed that AA metabolic pathways were mostly changed by the treatments, with reduced amination activity in roots most likely due to a shift from the biosynthesis of common AA to γ-amino butyric acid. The root metabolome differed between AMF and NAT but not AMF+PGPR and AMF or NAT. Because the PGPR used were potent mineralisers, and AMF can retain most nitrogen (N) taken as organic compounds for their own growth, it is likely that this result was due to an increased concentration of mineral N in soil inoculated with AMF+PGPR compared to AMF alone.
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy; Fondazione A. e S. Lima Mancuso, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Saia
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ruisi
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Fileccia
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy; Fondazione A. e S. Lima Mancuso, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Di Miceli
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Amato
authors.affiliation: Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Martinelli
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D002849:Chromatography, Gas; D019083:Mediterranean Region; D055432:Metabolomics / Q000379:methods; D038821:Mycorrhizae / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D014908:Triticum / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology*
chemical_list: D000596:Amino Acids; D012987:Soil; D010758:Phosphorus; D009584:Nitrogen