title: Proton (H+) flux signature for the presymbiotic development of the arbuscular mycorrhizal fungi.
abstract: Ion dynamics are important for cell nutrition and growth in fungi and plants. Here, the focus is on the relationship between the hyphal H(+) fluxes and the control of presymbiotic growth and host recognition by arbuscular mycorrhizal (AM) fungi. Fluxes of H(+) around azygopores and along lateral hyphae of Gigaspora margarita during presymbiotic growth, and their regulation by phosphate (P) and sucrose (Suc), were analyzed with an H(+)-specific vibrating probe. Changes in hyphal H(+) fluxes were followed after induction by root exudates (RE) or by the presence Trifolium repens roots. Differential sensitivity to P-type ATPase inhibitors (orthovanadate or erythrosin B) suggests an asymmetric distribution or activation of H(+)-pump isoforms along the hyphae of the AM fungi. Concentration of P and Suc affected the hyphal H(+) fluxes and growth rate. However, further increases in H+ efflux and growth rate were observed when the fungus was growing close to clover roots or pretreated with RE. The H(+) flux data correlate with those from polarized hyphal growth analyses, suggesting that spatial and temporal alterations of the hyphal H(+)fluxes are regulated by nutrient availability and might underlie a pH signaling elicitation by host RE during the early events of the AM symbiosis.
authors.affiliation: Centro de Biociências e Biotecnologia and Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes-RJ, 28015-620, Brazil.|Centro de Biologia do Desenvolvimento, Instituto Gulbenkian de Ciência, PT-2780-156 Oeiras, Portugal.
authors.forename: Alessandro C
authors.initials: AC
authors.lastname: Ramos
authors.affiliation: Centro de Biociências e Biotecnologia and Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes-RJ, 28015-620, Brazil.
authors.forename: Arnoldo R
authors.initials: AR
authors.lastname: Façanha
authors.affiliation: Centro de Biologia do Desenvolvimento, Instituto Gulbenkian de Ciência, PT-2780-156 Oeiras, Portugal.|Universidade de Lisboa, Faculdade de Ciências, Departamento de Biologia Vegetal, Campo Grande, Ed.C2. PT-1749-016, Lisboa, Portugal.
authors.forename: José A
authors.initials: JA
authors.lastname: Feijó
mesh_terms: D006863:Hydrogen-Ion Concentration; D025301:Hyphae / Q000254:growth & development / Q000378:metabolism*; D038821:Mycorrhizae / Q000254:growth & development / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011522:Protons; D013172:Spores, Fungal / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism; D013559:Symbiosis / Q000502:physiology*
chemical_list: D010710:Phosphates; D011522:Protons; D013395:Sucrose; D006180:Proton-Translocating ATPases