A pH signaling mechanism involved in the spatial distribution of calcium and anion fluxes in ectomycorrhizal roots.
Mycorrhization is a typical example of a host-pathogen symbiotic interaction where the pathogen cell biology and the host immune response coevolved several functional links. Here, the role played by ion fluxes across the root concerning nutrient uptake, osmoregulation, growth and signaling events is addressed. An ion-selective vibrating probe system was used to determine the net fluxes of protons (H(+)), calcium (Ca(2+)) and anions (A(-)) along nonmycorrhizal and ectomycorrhizal (ECM) roots of Eucalyptus globulus colonized by Pisolithus sp. These data show that, from five root zones analyzed, the main effect of fungal colonization was localized to the elongation zone. Here, strong changes in ion dynamics and rhizosphere acidification capacity were observed. Additionally, ion fluxes exhibited periodic fluctuations. To verify whether these fluctuations corresponded to sustained oscillations, continuous wavelet time spectrum analysis was applied and it was determined that H(+) and A(-) fluxes from ECM roots had longer periods than nonmycorrhizal roots. By contrast, Ca(2+) oscillations were completely abolished following fungal interaction. These results are interpreted in the light of a working model in which nutrient uptake and stimulation of growth are mediated by ECM fungi and may be pH-dependent. Furthermore, the variations detected in ECM roots for H(+) and A(-) fluxes suggest a main contribution from the plant, while the results obtained for Ca(2+) point to a significant involvement of the fungus.
Ramos
Alessandro C
AC
Instituto Gulbenkian de Ciência, Centro de Biologia do Desenvolvimento, Oeiras, 2780-901, Portugal;Depto de Microbiologia, Universidade Federal de Viçosa, Viçosa-MG, 36570-000, Brazil;Depto Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Campo Grande, 1700, Portugal.
Lima
Pedro T
PT
Instituto Gulbenkian de Ciência, Centro de Biologia do Desenvolvimento, Oeiras, 2780-901, Portugal;Depto de Microbiologia, Universidade Federal de Viçosa, Viçosa-MG, 36570-000, Brazil;Depto Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Campo Grande, 1700, Portugal.
Dias
Pedro N
PN
Instituto Gulbenkian de Ciência, Centro de Biologia do Desenvolvimento, Oeiras, 2780-901, Portugal;Depto de Microbiologia, Universidade Federal de Viçosa, Viçosa-MG, 36570-000, Brazil;Depto Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Campo Grande, 1700, Portugal.
Kasuya
Maria Catarina M
MCM
Instituto Gulbenkian de Ciência, Centro de Biologia do Desenvolvimento, Oeiras, 2780-901, Portugal;Depto de Microbiologia, Universidade Federal de Viçosa, Viçosa-MG, 36570-000, Brazil;Depto Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Campo Grande, 1700, Portugal.
Feijó
José A
JA
Instituto Gulbenkian de Ciência, Centro de Biologia do Desenvolvimento, Oeiras, 2780-901, Portugal;Depto de Microbiologia, Universidade Federal de Viçosa, Viçosa-MG, 36570-000, Brazil;Depto Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Campo Grande, 1700, Portugal.
D000838:Anions / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D005052:Eucalyptus / Q000378:metabolism* / Q000502:physiology; D005658:Fungi; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport / Q000502:physiology*; D025282:Mycelium / Q000378:metabolism; D038821:Mycorrhizae / Q000378:metabolism* / Q000502:physiology; D018517:Plant Roots / Q000378:metabolism; D036226:Seedlings; D015398:Signal Transduction; D013559:Symbiosis / Q000502:physiology
D000838:Anions; D002118:Calcium