Sporocarps of Pisolithus albus as an ecological niche for fluorescent pseudomonads involved in Acacia mangium Wild - Pisolithus albus ectomycorrhizal symbiosis.
Fresh sporocarps and root and soil samples were collected under a monospecific forest plantation of Acacia mangium in Dagana in Northern Senegal and checked for the presence of fluorescent pseudomonads. No bacteria were detected except from sporocarps collected with adhering soil and hyphal strands. Pisolithus sporocarps were dried at 30 degrees C for 2 weeks, ground, passed through a 2-mm sieve and mixed together. This dry sporocarp powder (DSP) was used to inoculate and form mycorrhizas on A. mangium seedlings in a glasshouse experiment. After 3 months culture, plant growth was increased in the DSP treatment but no ectomycorrhizas were present on the A. mangium root systems; however fluorescent pseudomonads were recorded in the cultural soil. The stimulatory effects on the plant growth were maintained for 6 months. However, fluorescent pseudomonads were no longer detected and 35% of the short roots were ectomycorrhizal. Some of the fluorescent pseudomonad isolates detected after 3 months stimulated the radial fungal growth in axenic conditions. These observations suggest that these bacteria are closely associated with the Pisolithus fructifications and could interact with the ectomycorrhizal symbiosis establishment.
Duponnois
Robin
R
UMR 113 CIRAD/INRA/IRD/AGRO-M/UM2, Laboratoire des Symbioses Tropicales et Méditerranéennes, Campus International de Baillarguet, Montpellier, France. Robin.Duponnois@ird.bf
Lesueur
Didier
D
D000045:Acacia / Q000254:growth & development / Q000382:microbiology*; D001487:Basidiomycota / Q000254:growth & development* / Q000502:physiology; D017753:Ecosystem; D038821:Mycorrhizae; D018517:Plant Roots / Q000382:microbiology; D011549:Pseudomonas / Q000254:growth & development*; D012988:Soil Microbiology; D013172:Spores, Fungal / Q000502:physiology*; D013559:Symbiosis; D014197:Trees